Simulated physiological oocyte maturation (SPOM): a novel in vitro maturation system that substantially improves embryo yield and pregnancy outcomes

BACKGROUND

Oocyte in vitro maturation (IVM) reduces the need for gonadotrophin-induced ovarian hyperstimulation and its associated health risks but the unacceptably low conception/pregnancy rates have limited its clinical uptake. We report the development of a novel in vitro simulated physiological oocyte maturation (SPOM) system.

METHODS AND RESULTS

Bovine or mouse cumulus-oocyte complexes (COCs) were treated with cAMP modulators for the first 1-2 h in vitro (pre-IVM), increasing COC cAMP levels ∼100-fold. To maintain oocyte cAMP levels and prevent precocious oocyte maturation, COCs were treated during IVM with an oocyte-specific phosphodiesterase inhibitor and simultaneously induced to mature with FSH. Using SPOM, the pre-IVM and IVM treatments synergized to increase bovine COC gap-junctional communication and slow meiotic progression (both P < 0.05 versus control), extending the normal IVM interval by 6 h in bovine and 4 h in mouse. FSH was required to complete maturation and this required epidermal growth factor signalling. These effects on COC had profound consequences for oocyte developmental potential. In serum-free conditions, SPOM increased bovine blastocyst yield (69 versus 27%) and improved blastocyst quality (184 versus 132 blastomeres; both P < 0.05 versus standard IVM). In mice, SPOM increased (all P < 0.05) blastocyst rate (86 versus 55%; SPOM versus control), implantation rate (53 versus 28%), fetal yield (26 versus 8%) and fetal weight (0.9 versus 0.5 g) to levels matching those of in vivo matured oocytes (conventional IVF).

CONCLUSIONS

SPOM is a new approach to IVM, mimicing some characteristics of oocyte maturation in vivo and substantially improving oocyte developmental outcomes. Adaption of SPOM for clinical application should have significant implications for infertility management and bring important benefits to patients.

Isolation and properties of cholesterol esterstorage granules from ovarian tissues

Cholesterol ester-storage granules were isolated from luteinized rat ovary and rabbit ovarian interstitial tissue by centrifugal flotation and were investigated with regard to their structure and function. Cholesterol ester, protein, phospholipid and unesterified cholesterol accounted for the dry weight of granules from luteinized rat ovary. The protein and the phospholipid were resistant to removal by washing. Substrate specificities of nucleotide phosphatase and specific radioactivities of lipid-soluble P (determined after administration of [(32)P]P(i)in vivo) were the same in granules and in a microsomal fraction from the same tissue. After administration of [(32)P]P(i)in vivo, luteinizing hormone increased the specific radioactivity of lipid-soluble P in granules, mitochondria and the microsomal fraction. Since granules did not swell in hypo-osmotic media, whereas microsomal particles did, it is suggested that adherent phospholipid and protein in granule suspensions is unlikely to result from contamination with endoplasmic reticulum. Luteinizing hormone administered in vivo increased the phospholipid and unesterified cholesterol contents of isolated granules relative to their cholesterol ester content, and also tended to raise their protein content. This treatment decreased the ability of isolated granules to act as a substrate for cholesterol esterase in vitro and increased the activity of cholesterol esterase. Cycloheximide in vivo also raised the unesterified cholesterol/cholesterol ester ratio of isolated granules, and when administered with luteinizing hormone acted synergistically to bring about a further increase. These results are considered compatible with evidence obtained by microscopy which suggests that granules may be surrounded by a membrane, that they arise by pinching off from the endoplasmic reticulum, and that they shrink on trophic stimulation of the tissue.

131. INDUCED OOCYTE IN VITRO MATURATION (IVM) SUBSTANTIALLY IMPROVES EMBRYO YIELD AND PREGNANCY OUTCOMES

Oocyte maturation in vivo is a highly orchestrated, induced process, whereby 3'-5'-cyclic adenosine monophosphate (cAMP)-mediated meiotic arrest is overridden by the gonadotrophin surge prior to ovulation. However, in vitro matured (IVM) oocytes resume maturation spontaneously hence compromising developmental competence. Hence we hypothesized that establishing an induced system in vitro would synchronise oocyte-somatic cell communication leading to improved oocyte quality. Bovine or mouse oocytes were treated for the first 1-2 h in vitro with the adenylate cyclase activator forskolin and a non-specific phosphodiesterase (PDE) inhibitor, IBMX, which substantially increased cumulus-oocyte complex (COC) cAMP (180 vs. 2 fmol/ COC , treated vs. control, P<0.001) to in vivo physiological levels. To maintain oocyte cAMP levels and prevent precocious oocyte maturation, oocytes were then cultured with an oocyte-specific (type 3) PDE inhibitor, cilostamide. The net effect of this system (“Induced IVM”) was to increase oocyte-somatic cell gap-junctional communication (bovine: 1000±148 vs. 340±73 units; treated vs. control, p<0.05) and to slow meiotic progression through prophase I to metaphase II, extending the normal IVM interval (bovine: 30 vs. 24h, mouse: 22 vs. 18 h; treated vs. control). These effects on oocyte and somatic cell functions had profound consequences for oocyte developmental potential. In bovine, Induced IVM more than doubled embryo yield (69% vs. 27%; treated vs. control, p<0.05). In mouse, Induced IVM increased blastocyst rate (86% vs. 55%; treated vs. control, p<0.05), implantation rate (51 vs. 25%), fetal survival rate (29% vs. 5%) and fetal weight (0.9g vs. 0.5g, p<0.01). All these developmental outcomes in mice were restored, by using Induced IVM, to levels obtained from in vivo matured control oocytes (conventional IVF). In conclusion, Induced IVM mimics some of the characteristics of oocyte maturation in vivo and substantially improves oocyte developmental outcomes. This should lead to an increase in the use of this technique in reproductive biotechnologies.

260. Synergistic effects of cAMP modulating agents in pre-IVM and in IVM on bovine cumulus and oocyte functions

Cyclic AMP plays a crucial role in oocyte maturation. It has been shown that prolonging spontaneous maturation by modulating oocyte cAMP levels during in vitro maturation (IVM) improves developmental outcomes. This study sought to assess the effect of inclusion of cAMP modulators during a pre-IVM phase and during IVM on cumulus cell (CC) and oocyte function. Bovine cumulus-oocyte complexes (COCs) were precultured for 2 h in medium supplemented with/without cAMP modulators: 0.5 mM IBMX and 0.1 mM forskolin (FK). Cyclic AMP in control COCs dropped significantly from 15 ± 4 to 2 ± 1 fmol/COC within 30 min, whereas FK+IBMX during pre-IVM increased levels to 180 ± 19 fmol/COC, which had notable persistent effects on several COC functions throughout IVM. Cyclic AMP modulators delayed oocyte GV progression; after 2 h of pre-IVM, 67 ± 5% were at GVII stage compared (P < 0.0001) to 12 ± 3% in controls, 66 ± 5% of which had progressed to GVIII. This was associated with a significantly higher level of oocyte-CC gap junction mediated communication (1000 ± 148 v. 340 ± 73 units). We next assessed the interaction of cAMP modulators in pre-IVM and IVM (20uM cilostamide) phases. After 9 h of IVM, significantly more oocytes were arrested at GV stage when modulators were present in both pre-IVM and IVM phases, compared with in IVM alone (96 ± 1 v. 74 ± 2%, P < 0.05). Moreover, progression to MII was delayed by modulators in pre-IVM and IVM (24 ± 1, 75 ± 2, 92 ± 1% MII at 20, 24 and 28 h, respectively), compared with in IVM alone (78 ± 1, 95 ± 1, 98 ± 2% MII). After 24 h of IVM, intra-oocyte cAMP levels remained 15-fold higher (P < 0.05) with modulators in both phases compared with in IVM alone. These results show that the efficacy of cAMP modulators during IVM is substantially improved by management of COC cAMP levels during the pre-IVM phase. Such an approach has profound effects on CC and oocyte function, including increasing oocyte-CC communication and delaying meiotic resumption.

Effects of ovarian stimulation, with and without human chorionic gonadotrophin, on oocyte meiotic and developmental competence in the marmoset monkey (Callithrix jacchus)

A reliable ovarian stimulation protocol for marmosets is needed to enhance their use as a model for studying human and non-human primate oocyte biology. In this species, a standard dose of hCG did not effectively induce oocyte maturation in vivo. The objectives of this study were to characterize ovarian response to an FSH priming regimen in marmosets, given without or with a high dose of hCG, and to determine the meiotic and developmental competence of the oocytes isolated. Ovaries were removed from synchronized marmosets treated with FSH alone (50 IU/d for 6 d) or the same FSH treatment combined with a single injection of hCG (500 IU). Cumulus-oocyte complexes (COCs) were isolated from large (>1.5mm) and small (0.7-1.5mm) antral follicles. In vivo-matured oocytes were subsequently activated parthenogenetically or fertilized in vitro. Immature oocytes were subjected to in vitro maturation and then activated parthenogenetically. Treatment with FSH and hCG combined increased the number of expanded COCs from large antral follicles compared with FSH alone (23.5 +/- 9.3 versus 6.4 +/- 2.7, mean +/- S.E.M.). Approximately 90% of oocytes surrounded by expanded cumulus cells at the time of isolation were meiotically mature. A blastocyst formation rate of 47% was achieved following fertilization of in vivo-matured oocytes, whereas parthenogenetic activation failed to induce development to the blastocyst stage. The capacity of oocytes to complete meiosis in vitro and cleave was positively correlated with follicle diameter. A dramatic effect of follicle size on spindle formation was observed in oocytes that failed to complete meiosis in vitro. Using the combined FSH and hCG regimen described in this study, large numbers of in vivo matured marmoset oocytes could be reliably collected in a single cycle, making the marmoset a valuable model for studying oocyte maturation in human and non-human primates.

342 DISTINCT EFFECTS OF FOLLICULAR FLUID ON CUMULUS CELL APOPTOSIS AND PORCINE OOCYTE DEVELOPMENTAL COMPETENCE

Supplementing medium with follicular fluid (FF) during in vitro maturation (IVM) enhances the developmental competence of porcine oocytes, indicating that factors present in FF are beneficial to cytoplasmic maturation. Previous findings suggest that porcine FF contains high levels of superoxide dismutase activity and exerts a beneficial effect on cytoplasmic maturation by protecting oocytes from oxidative stress (Tatemoto et al. 2004 Biol. Reprod. 71, 1150–1157). Since oxidative stress is a potent inducer of apoptosis, the aim of the present study was to examine the temporal effects of FF during IVM on cumulus cell apoptosis and oocyte developmental competence. Ovaries of prepubertal pigs were collected from a local abattoir and antral follicles, 3 to 7 mm in diameter, were aspirated. Cumulus–oocyte complexes (COCs) with at least 3 uniform layers of compact cumulus cells (CCs) were recovered, washed, and transferred to maturation medium (MM) with or without 25% FF. At 22 h of IVM, COCs from each group were washed and transferred to fresh MM with or without 25% FF, forming 4 groups: -FF/-FF, -FF/+FF, +FF/-FF, and +FF/+FF. Cohorts of COCs were TUNEL stained at 22 and 44 h of IVM using the In Situ Cell Death Detection kit (Roche Diagnostics, Castle Hill, NSW, Australia) according to the manufacturer&apos;s instructions, and apoptotic CCs were visualized using confocal microscopy. Oocytes denuded at 44 h, that had a polar body, were treated with ionomycin and 6-dimethylaminopurine to induce parthenogenetic development, and were cultured for 7 days in NCSU-23 medium at 38.5&deg;C in 5&percnt; O2, 5&percnt; CO2, and 90&percnt; N2. Data were subjected to ANOVA and Tukey&apos;s post-hoc test. At 22 h of IVM, the presence of FF reduced the proportion of apoptotic CCs in COCs (2.1&percnt; vs. 4.6&percnt;). COCs matured with FF from 22 to 44 h of IVM had much lower proportions of apoptotic CCs (&plus;FF/&plus;FF: 0.9&percnt;; &minus;FF/&plus;FF: 2.6&percnt;) compared with those matured without FF (&plus;FF/&minus;FF: 10.3&percnt;; &minus;FF/&minus;FF: 17.8&percnt;). The rate of maturation to the metaphase-II stage was greater when oocytes were matured with FF from 0 to 22 h of IVM (&minus;FF/&minus;FF: 68.6&percnt;; &minus;FF/&plus;FF: 72.8&percnt;; &plus;FF/&minus;FF: 89.2&percnt;; &plus;FF/&plus;FF: 86.2&percnt;). Maturation without FF for the entire IVM interval reduced the proportion of activated oocytes that formed blastocysts compared with the other groups (&minus;FF/&minus;FF: 25.1&percnt;; &minus;FF/&plus;FF: 44.6&percnt;; &plus;FF/&minus;FF: 46.6&percnt;; &plus;FF/&plus;FF: 47.3&percnt;). Despite a 4-fold difference in the proportion of apoptotic CCs between COCs of the &plus;FF/&minus;FF and &minus;FF/&plus;FF groups, exposure to FF for the first or second half of IVM was as beneficial to oocyte developmental competence as exposure to FF for the entire IVM interval. This suggests that the protective effect of FF in reducing oxidative stress on oocytes during IVM is distinct from the effect on oocyte developmental competence.

Seminal plasma regulates ovarian progesterone production, leukocyte recruitment and follicular cell responses in the pig

Seminal plasma (SP) acts to influence the uterine endometrium after mating, activating synthesis of embryotrophic cytokines and inflammatory changes that condition the tract for embryo implantation and establishing pregnancy. The objective of this study was to investigate in pigs whether the ovary might also be responsive to SP exposure. Prepubertal gilts were synchronised with exogenous gonadotrophins and received transcervical treatment with pooled boar SP or PBS; then the ovarian tissue was recovered at 34 h (preovulation) and on days 5 and 9 after treatment. The ovarian response was assessed by measuring ovulation rate, number and size of corpora lutea, ovarian leukocyte populations, progesterone production in vivo, as well as responses of retrieved granulosa cells cultured in vitro. In SP-treated gilts, leukocyte recruitment into the ovarian tissues was increased fourfold at 34 h, with macrophages comprising the most abundant cell lineage. There was no effect of SP on the number of oocytes ovulated; however, the weight of corpora lutea was increased in SP-treated gilts. SP also induced an increase in plasma progesterone content seen from day 5 to at least day 9 after treatment. In addition, granulosa cells and thecal tissue retrieved from preovulatory follicles of SP-treated gilts were more responsive in vitro to growth factor- and gonadotrophin-stimulated cell proliferation and progesterone synthesis. These results suggest that uterine exposure to SP influences immune cell trafficking in the ovary and enhances steroidogenesis in early pregnancy. The effects of SP on ovarian function potentially contribute to reproductive success in the pig.

Adipokines: implications for female fertility and obesity

Obesity is associated with a diverse set of metabolic disorders, and has reproductive consequences that are complex and not well understood. The adipose tissue-produced leptin has dominated the literature with regards to female fertility complications, but it is pertinent to explore the likely role of other adipokines--adiponectin and resistin--as our understanding of their biological functions emerge. Leptin influences the developing embryo, the functioning of the ovary and the endometrium, interacts with the release and activity of gonadotrophins and the hormones that control their synthesis. In this review such biological actions and potential roles of the adipokines leptin, adiponectin and resistin are explored in relation to female fertility and the complexity of the obese metabolic state.

Influence of semen on inflammatory modulators of embryo implantation

Insemination transmits to the female reproductive tract constituents of seminal plasma that target uterine epithelial cells to activate a cascade of inflammatory and immunological changes. Experiments in rodents show seminal factor signalling acts to 'condition' the female immune response to tolerate the conceptus, and to organise molecular and cellular changes in the endometrium to facilitate embryo development and implantation. The active factors in seminal plasma are identified as members of the transforming growth factor-beta family, with the relative balance of active moieties influencing the precise character of the female tract response. Experiments in rodents show that disruption of seminal plasma priming causes foetal growth retardation and changes in placental structure, with long-term consequences for the growth of the neonate. Recent studies indicate a similar physiological function and molecular basis for seminal plasma actions in the pig. In gilts, seminal plasma elicits an endometrial response characterised by recruitment of inflammatory leukocytes and induction of several pro-inflammatory cytokines and cyclo-oxygenase-2. The consequences are evident throughout the pre-implantation period of early pregnancy with altered leukocyte populations and cytokine parameters seen for at least 9 days. Exposure to semen also alters the dynamics in pre-implantation embryo development with an increase in the number of embryos and in their viability. Furthermore seminal plasma influences the temporal kinetics of ovulation, corpus luteum development and steroid production in the ovary. Dissecting the actions of seminal plasma may facilitate development of strategies to ensure maximal fertility and reduce embryo mortality in the pig.

Androgens Augment the Mitogenic Effects of Oocyte-Secreted Factors and Growth Differentiation Factor 9 on Porcine Granulosa Cells1

In this study, we test the hypothesis that the growth-promoting action of androgens on granulosa cells requires paracrine signaling from the oocyte. Mural granulosa cells (MGCs) from small antral (1-3 mm) prepubertal pig follicles were cultured in the presence or absence of denuded oocytes (DO) from the same follicles to determine whether mitogenic and/or steroidogenic responses, to combinations of FSH, insulin-like growth factor 1 (IGF1), and dihydrotestosterone (DHT) were influenced by oocyte-secreted factors (OSFs). To further explore the identity of such factors we performed the same experiments, substituting growth differentiation factor 9 (GDF9), a known OSF, for the DO. OSFs and GDF9 both potently enhanced IGF1-stimulated proliferation, and inhibited FSH-stimulated progesterone secretion. Alone, DHT had little effect on DNA synthesis, but significantly enhanced the mitogenic effects of OSFs or GDF9 in the presence of IGF1. Denuded oocytes, GDF9, and DHT independently inhibited FSH-stimulated progesterone secretion, and androgen, together with DO or GDF9, caused the most potent steroidogenic inhibition. Focusing on mitogenic effects, we demonstrate that both natural androgen receptor (AR) agonists, testosterone and DHT, dose-dependently augmented the mitogenic activity of DO or GDF9. Antiandrogen (hydroxyflutamide) treatment, which is used to block androgen receptor activity, opposed the interaction between androgen and GDF9. In conclusion, androgens stimulate porcine MGC proliferation in vitro by potentiating the growth-promoting effects of oocytes or GDF9, via a mechanism that involves the AR. These signaling pathways are likely to be important regulators of folliculogenesis in vivo, and may contribute to the excess follicle growth that is observed in androgen-treated female animals.

Effects of recombinant human follicle-stimulating hormone on embryo development in mice

We have developed a protocol using recombinant human follicle-stimulating hormone (rhFSH) to induce ovarian stimulation in the mouse to investigate its impact on preimplantation embryo development. Embryos were collected from adult female C57Bl/6 x CBA F1 mice treated with rhFSH (0, 2.5, 5.0, 10.0, or 20.0 IU) or 5 IU equine chorionic gonadotropin (eCG). Embryos were also recovered from nontreated control mice. Embryos were cultured in vitro for 88 h, and the stage of development was morphologically assessed. The allocation of cells to the inner cell mass or trophectoderm of blastocysts was determined by differential nuclear staining. The expression of insulin-like growth factor 2 (IGF-II), the insulin-like growth factor receptor (IGF-II receptor), and vascular endothelial growth factor (VEGF) in blastocysts was measured by real-time RT-PCR. Blastocyst development was reduced in the 10 (72.3 +/- 5.1%) and 20 (77.3 +/- 5.6%) IU rhFSH groups compared with control embryos (96.7 +/- 1.0%). The number of inner cell mass cells was reduced (P < 0.001) in the 5, 10, and 20 IU rhFSH groups and the eCG group compared with control embryos. We did not find any effect of rhFSH treatment on IGF-II, IGF-II receptor, or VEGF expression in blastocysts compared with the control group. eCG treatment, however, significantly increased the expression of IGF-II in blastocysts. These results indicate that ovarian stimulation with rhFSH impairs the in vitro development of preimplantation mouse embryos, and these results may have potential implications for clinical ovarian stimulation during infertility treatment and subsequent embryo quality.

254. Effect of donor age and follicle size on oocyte developmental competence in the pig

Oocytes utilised for in vitro embryo production (IVP) are typically derived from 3–8 mm ovarian follicles of slaughtered pre-pubertal pigs. Following in vitro maturation (IVM), pre-pubertal oocytes display lower developmental competence (DC) than adult oocytes. The aim of this study was to determine the proportion of follicles 3, 4, and 5–8 mm in diameter on the surface of pre-pubertal and adult ovaries, and assess DC of corresponding oocytes. Oocytes were matured for 46 h in modified medium 199. Mature oocytes from the three follicle size cohorts were activated with calcium ionophore to assess blastocyst embryo formation rate. Data were subjected to arcsine transformation, ANOVA and the Tukey post-hoc test. Compared with adult ovaries, pre-pubertal ovaries contained a higher proportion of 3 mm follicles (46 ± 4 v. 72 ± 4%, P<0.01), but a lower proportion of 4 mm (33 ± 3 v. 22 ± 3%, P<0.01) and 5–8 mm follicles (21 ± 5 v. 6 ± 2%, P<0.01). Adult oocytes from the three follicle sizes displayed similar DC (41±2% to 47±3%). DC of pre-pubertal oocytes improved with increasing follicle size (3 mm < 4 mm < 5–8 mm; 12±4%, 27±8% and 50±8%, respectively; P < 0.05). In conclusion, the predominance of 3 mm follicles accounts for the low DC of oocytes from pre-pubertal donors compared with adult donors. Further research is required to understand DC acquisition in pre-pubertal pig oocytes from the smaller follicles <5mm in diameter.

253. Calcium ionophore induction of marmoset oocyte activation

The marmoset monkey (Callithrix jacchus) is a valuable model for developing assisted reproductive technologies in humans and endangered primate species. Calcium ionophore treatments have been used to induce parthenogenetic activation in a number of species, but the effectiveness of this reagent in initiating marmoset embryo development has not yet been reported. The aim of this study was to determine the developmental potential of in vitro matured (IVM) marmoset oocytes, following treatment with calcium ionophore. Immature oocytes from large (LA; >1.5 mm) and small (SA; 0.67–1.5 mm) antral follicles were isolated from the ovaries of FSH-primed animals and cultured in modified G2 medium for 26–30 h at 37.0°C in 6% CO2 in air. Meiotically mature oocytes were sequentially incubated with 5 μM ionomycin for 5 min and 2 mM 6-dimethylaminopurine for 3 h and cultured in G1/G2 sequential medium at 37.0°C in 5% O2, 6% CO2, 89% N2 for 10 days. Cumulus cell expansion associated with LA oocytes (n=118) was greater than that of SA oocytes (n=212), as determined using well established classification criteria (2.7±0.1 v. 1.8±0.2; P<0.01). A greater proportion of LA oocytes completed meiosis to the metaphase-II stage compared with SA oocytes (85±7% v. 63±7%; P<0.05). Pronuclear formation was induced at similar rates in mature oocytes of both groups, but the rate of cleavage was higher for LA oocytes compared with SA oocytes (93±6% v. 66±5%; P<0.05). The number of cells per embryo was not different between the groups.This is the first study to demonstrate that calcium ionophore effectively induces parthenogenetic activation in IVM marmoset oocytes. However, the development of parthenotes was limited beyond the 8-cell stage. Further studies are needed to determine the cause of the developmental block.

251. Growth differentiation factor 9 signalling systems regulate marmoset monkey granulosa cell proliferation

This study was conducted to characterize the receptor/signalling system utilized by the oocyte-secreted growth differentiation factor 9 (GDF9) to promote granulosa cell (GC) growth in the marmoset monkey. Seven adult female marmosets were primed with hFSH for 6 days, whole ovaries were removed on day 7, follicles manually excised, and GC collected from 3 size classes: periantral (PA; 0.42–0.66mm), small antral (SA; 0.66–1.5mm) and large antral (LA; >1.5mm). RNA was extracted from oocytes and GC and subjected to RT-PCR using human primers. In all follicle size classes oocytes expressed GDF9 mRNA and GC expressed mRNA for key GDF9 signalling molecules; bone morphogenetic protein receptor II, activin receptor-like kinase (ALK) 5 and Smad 3. To examine the intracellular response to GDF9, cultured GC from LA follicles were transfected with luciferase reporter constructs and treated with growth factors. CAGA-luciferase (Smad 3 pathway) in transfected GC was stimulated by TGFβ1 (18× above control), GDF9 and mouse oocytes (both ~5×), but not by BMP7. Conversely, neither TGFβ1, GDF9 nor oocytes activated BRE-luciferase (Smad 1/5/8 pathway), which was stimulated 30× by BMP7. 3H-thymidine incorporation was used to determine the effects of GDF9 on GC proliferation. Basal incorporation was highly dependent on follicle size, with PA follicles ~10× higher than SA and ~30× higher than LA follicles. GDF9 stimulated 3H-uptake in GC from all sized follicles, most potently in PA and SA cells. The mitogenic effect of GDF9 was amplified by IGF1; ~3× in SA GC and ~5× in LA GC. In contrast, in the presence of FSH or FSH+IGF1, GDF9 did not stimulate GC proliferation. Treatment of GC with an ALK4/5/7 kinase inhibitor, SB431542, antagonized both GDF9 and GDF9+IGF1 mitogenic effects, in a dose-dependent manner. Thus, GDF9 potently stimulates primate GC proliferation utilizing components of the TGFβ signalling system initially identified in rodents.

231. Mouse oocyte paracrine signalling to cumulus cells by TGF-β superfamily molecules is indispensable for cumulus expansion

Oocyte-secreted factors are required for expansion of the mouse cumulus-oocyte complex (COC), which is necessary for ovulation. Members of the transforming growth factor-β (TGF-β) superfamily are prime candidates for the mouse cumulus expansion-enabling factor (CEEF), and we have recently determined that growth differentiation factor 9 (GDF9) alone is not the CEEF. This study was conducted to examine TGF-β superfamily processes regulating cumulus expansion. COCs were collected from eCG-primed mice and the oocyte microsurgically removed to generate oocytectomised (OOX) complexes. An established scoring system was used to measure FSH-induced cumulus expansion; 0 (no expansion) to +4 (maximum expansion). OOX complexes treated with FSH alone failed to expand (score: 0), whereas expansion was significantly (P < 0.05) induced by either GDF9 (score: mean ± SEM, 3.7 ± 0.1), activin A (2.6 ± 0.1), or co-culture with oocytes (3.2 ± 0.2). The type-I receptors for GDF9 and activin are activin receptor-like kinase 5 (ALK5) and ALK4, respectively. We tested the ability of the ALK4/5/7 kinase inhibitor, SB431542, to neutralise cumulus expansion. SB431542 completely neutralised (P < 0.05) the response of OOX complexes to GDF9, activin and oocyte-induced cumulus expansion. SB431542 also neutralised (P < 0.05) COC expansion in a dose dependent manner. Follistatin, an activin antagonist was effective at neutralising the response of OOX complexes to activin (score: 0), but had no significant effect (P > 0.05) on the expansion of OOX complexes co-cultured with oocytes (score: 2.7 ± 0.2). This study provides evidence that activin is not the sole CEEF, but signalling through the ALK4/5/7 pathway is indispensable for mouse cumulus expansion.

270. Androgens augment the mitogenic effects of oocyte-secreted factors and growth differentiation factor 9 on porcine granulosa cells

Androgens, acting directly through the androgen receptor (AR), are thought to promote granulosa cell (GC) growth in vivo, but generally inhibit growth and promote GC differentiation in vitro. We hypothesised that the growth-promoting action of androgens on GC requires paracrine signalling from the oocyte. To test this hypothesis, we cultured mural GC from small antral (1–3mm) pre-pubertal pig follicles in the presence or absence of denuded oocytes (DO) from the same follicles to examine whether mitogenic responses, determined by uptake of tritiated thymidine, to combinations of FSH, insulin like growth factor 1 (IGF1) and dihydrotestosterone (DHT; 500 nM), were influenced by oocyte-secreted factors (OSFs). To further explore the identity of such factors, we performed the same experiments, substituting recombinant mouse growth differentiation factor 9 (GDF9), a known OSF, for the DO. Alone, DHT induced a small (<2-fold), but consistent increase in IGF1-stimulated DNA synthesis. OSFs stimulated DNA synthesis in all experimental combinations, most significantly in the presence of IGF1 (P < 0.0001), and DHT enhanced (P<0.05) the stimulatory effect of OSFs in all instances. Like OSFs, GDF9 substantially increased IGF1-stimulated DNA synthesis (P < 0.0001), and again, DHT enhanced (P > 0.01) this effect. In further experiments, two AR agonists, testosterone (10-1000nM) and DHT (5–500 nM), dose-dependently augmented the mitogenic effect of OSFs or GDF9 in the presence of IGF1. Only the highest doses of androgen had an independent stimulatory effect; lower doses required the presence of an OSF(s). Antiandrogen (hydroxyflutamide) treatment, used to block AR activity, antagonized the androgen X GDF9 interaction. In conclusion, androgens, via activation of the AR, stimulate porcine GC proliferation in vitro by potentiating the growth-promoting effects of oocytes or GDF9. These signalling pathway interactions are likely to be important regulators of folliculogenesis in vivo and may cause the excess follicle growth that is observed in androgen-treated female animals.

Oocyte-somatic cell interactions during follicle development in mammals

Our current perspectives on the relationship between the oocyte and its surrounding somatic cells are changing as we gain a greater understanding of factors regulating folliculogenesis. It is now widely accepted that the oocyte plays a very active role in promoting follicle growth and directing granulosa cell differentiation. The oocyte achieves this, in part, by secreting soluble paracrine growth factors that act on its neighboring granulosa cells, which in turn regulate oocyte development. In preantral follicles, the oocyte directs granulosa cells to regulate oocyte growth, and oocytes may also directly drive follicle growth. In antral follicles, the oocyte governs the behaviour of cells in its immediate vicinity, thereby actively regulating its own microenvironment. As such, the oocyte establishes and maintains the distinct cumulus lineage of granulosa cells. This oocyte-cumulus cell interaction, in general, prevents luteinization of cumulus cells by promoting growth, regulating steroidogenesis and inhibin synthesis, and suppressing luteinizing hormone receptor expression. Conversely, mural granulosa cells in antral follicles, which have no direct physical contact with the oocyte and, presumably, experience a more diffuse concentration of oocyte-secreted factors, proceed to a different phenotype. In the ovulating follicle, oocyte-secreted factors also play vital roles in enabling cumulus cell expansion and regulating extracellular matrix stability, thus facilitating ovulation. The identities of these oocyte-secreted growth factors regulating such key ovarian functions remain unknown, although growth differentiation factor-9 (GDF-9), GDF-9B and/or bone morphogenetic protein-6 (BMP-6) are likely candidate molecules, probably forming complex local interactions with other related members of the transforming growth factor-beta (TGF-beta) superfamily. Elucidating the nature of oocyte-somatic cell interactions at the various stages of follicle development will have important implications for our understanding of factors regulating folliculogenesis, ovulation rate and fecundity.

Effect of Specific Phosphodiesterase Isoenzyme Inhibitors During In Vitro Maturation of Bovine Oocytes on Meiotic and Developmental Capacity1

Compared with oocytes matured in vivo, in vitro-matured oocytes are compromised in their capacity to support early embryo development. Delaying spontaneous in vitro meiotic maturation using specific phosphodiesterase (PDE) isoenzyme inhibitors may permit more complete oocyte cytoplasmic maturation, possibly by prolonging cumulus cell (CC)-oocyte gap junctional communication during meiotic resumption. This study aimed to investigate the effect of the isoenzyme 3- (oocyte) and isoenzyme 4- (granulosa cell) specific PDE inhibitors on the kinetics of in vitro maturation and on subsequent oocyte developmental competence. Cumulus-oocyte complexes from antral bovine follicles were isolated and cultured in the presence of the specific PDE inhibitors milrinone (type 3) or rolipram (type 4) (100 microM). In the presence of FSH, both PDE inhibitors only slightly extended CC-oocyte gap junctional communication over the first 9 h, but they completely blocked meiotic resumption during this period (P < 0.001). The indefinite inhibitory effect of milrinone on meiotic resumption (30% at germinal vesicle stage after 48 h) was overridden by 24 h when treated with FSH, but not with hCG, suggesting a form of induced meiotic resumption. Oocytes treated with FSH with or without either PDE inhibitor were inseminated at either 24, 26, or 28 h. Treated with either the type 3 or type 4 PDE inhibitor significantly (P < 0.05) increased embryo development to the blastocyst stage by 33%-39% (to an average of 52% blastocysts) compared with control oocytes (38%) after insemination at 28 h, and significantly (P < 0.05) increased blastocyst cell numbers when inseminated at 24 h. These results suggest that delayed spontaneous meiotic maturation, coupled with extended gap junctional communication between the CCs and the oocyte has a positive effect on oocyte cytoplasmic maturation, thereby improving oocyte developmental potential.

Changes in ovarian, follicular, and oocyte morphology immediately after the onset of puberty are not accompanied by an increase in oocyte developmental competence in the pig

This study was conducted to determine whether ovarian morphology and developmental competence of in vitro-matured (IVM) oocytes is immediately affected by the onset of puberty in the pig. Ovaries of peri-pubertal pigs were sorted into two groups according to the presence or absence of corpora lutea presence (CL and NCL, respectively. Ovary dimensions, follicle diameter and number, and oocyte diameter (with and without zona pellucidae) were determined. The developmental competence of in vitro-matured oocytes from these two groups was evaluated following parthenogenetic activation and culture in vitro. CL ovaries were significantly (P<0.01) larger than NCL ovaries (width: 22.3+/-0.9 mm versus 15.9+/-0.4 mm, length: 33.2+/-1 mm versus 24.1+/-0.4 mm). Although CL ovaries had fewer antral follicles in total compared with NCL ovaries (21.1+/-1.8 mm versus 46.8+/-2.2 mm), they had a similar number of follicles 3-8mm in diameter. The mean diameter of follicles that were aspirated was greater for CL ovaries than for NCL ovaries (4.5+/-0.1 mm versus 3.3+/-0.02 mm). Oocytes from CL ovaries were greater in diameter compared with those from NCL ovaries (zona retained: 159+/-1.3 microm versus 146.1+/-1.5 microm, zona free: 124.7+/-1.8 microm versus 113.1+/-1.6 microm). No differences were found between oocytes from CL and NCL ovaries for rates of meiotic maturation (91.6+/-3.2% versus 92.4+/-3.2%), cleavage (88.4+/-11% versus 90.7+/-2.6%) and blastocyst formation (21.0+/-3.7% versus 23.7+/-5.7%). Therefore, the onset of puberty coincides with immediate changes in ovarian morphology, increased ovary size, follicle and oocyte diameter, but not with improved oocyte developmental competence. This suggests that the higher developmental competence usually observed in adult oocytes is acquired gradually and requires exposure to multiple estrus cycles.

Seminal plasma regulates endometrial cytokine expression, leukocyte recruitment and embryo development in the pig

In pigs, uterine exposure to the constituents of semen is known to increase litter size but the underlying physiological mechanisms remain undefined. Studies in rodents and humans implicate immune modulating moieties in seminal plasma as likely candidates, acting through enhancing the receptivity of the female tract. In this study, the acute and longer term effects of seminal plasma on cytokine expression and leukocyte abundance in the pig endometrium during early pregnancy have been characterised. The reproductive tracts of gonadotrophin-primed pre-pubertal gilts treated with intrauterine infusions of either pooled seminal plasma or phosphate-buffered saline (PBS) were retrieved at 34 h, or on day 5 and day 9 after treatment. Seminal plasma elicited an endometrial inflammatory infiltrate comprised of predominantly macrophages and major histocompatibility complex class II+-activated macrophages and dendritic cells. The abundance of these cells was greatest at the pre-ovulatory (34 h) time-point and their increase relative to PBS-treated tissues was maintained until day 9 after seminal plasma treatment. Seminal plasma induced the expression of the cytokines, granulocyte macrophage colony-stimulating factor, interleukin-6 and monocyte chemoattractant protein-1, and the eicosanoid-synthesising enzyme cyclo-oxygenase-2. Expression was maximal 34 h after treatment but altered expression patterns as a consequence of seminal plasma induction persisted through early pregnancy. These changes were accompanied by altered dynamics in pre-implantation embryo development with an increase in the number of embryos and in their viability after seminal plasma treatment. Together, these findings implicate factors in seminal plasma in programming the trajectory of uterine cytokine expression and leukocyte trafficking during early pregnancy and in regulating pre-implantation embryo development in the pig.

Interactions Between Androgen and Growth Factors in Granulosa Cell Subtypes of Porcine Antral Follicles1

Androgens acting via the androgen receptor (AR) have been implicated in regulation of folliculogenesis in many animal species. These effects are possibly mediated via enhancement of FSH and/or insulin-like growth factor (IGF)-I activity in granulosa cells, which contain high levels of AR protein. We examined the in vitro effect of dihydrotestosterone (DHT) on DNA synthesis and progesterone secretion by follicular cells in response to FSH and IGF-I, alone or in combination. Cells from separate pools of 1- to 3-mm and 3- to 5-mm antral follicles were aspirated from gilt ovaries and fractioned into mural granulosa cells (MGCs) and cumulus-oocyte complexes (COCs) for subsequent cell culture. Androgen alone or with any combination of mitogen had minimal effect on proliferative and no effect on steroidogenic responses of MGCs from 3- to 5-mm antral follicles. Conversely, in MGCs from 1- to 3-mm follicles, DHT significantly enhanced IFG-I-stimulated proliferation and had variable influence on progesterone secretion. The effects of DHT on proliferative responses of COCs were also dependent on follicle size: DHT significantly augmented either IGF-I-stimulated proliferation (1- to 3-mm follicles) or FSH-stimulated proliferation (3- to 5-mm follicles). However, the steroidogenic responses of all COCs were identical, whereby DHT significantly suppressed progesterone secretion, predominantly in the presence of FSH. Addition of an AR antagonist, hydroxyflutamide, generally reversed the proliferative responses invoked by DHT but not the steroidogenic responses. We conclude that androgen-receptor-mediated activity in granulosa cells of antral follicles is dependent on follicle size, is influenced by proximity of cells to the oocyte, and possibly involves both classic and nonclassic steroid mechanisms.

Oxygen-regulated gene expression in bovine blastocysts

Oxygen concentrations used during in vitro embryo culture can influence embryo development, cell numbers, and gene expression. Here we propose that the preimplantation bovine embryo possesses a molecular mechanism for the detection of, and response to, oxygen, mediated by a family of basic helix-loop-helix transcription factors, the hypoxia-inducible factors (HIFs). Day 5 compacting bovine embryos were cultured under different oxygen tensions (2%, 7%, 20%) and the effect on the expression of oxygen-regulated genes, development, and cell number allocation and HIFalpha protein localization were examined. Bovine in vitro-produced embryos responded to variations in oxygen concentration by altering gene expression. GLUT1 expression was higher following 2% oxygen culture compared with 7% and 20% cultured blastocysts. HIF mRNA expression (HIF1alpha, HIF2alpha) was unaltered by oxygen concentration. HIF2alpha protein was predominantly localized to the nucleus of blastocysts. In contrast, HIF1alpha protein was undetectable at any oxygen concentration or in the presence of the HIF protein stabilizer desferrioxamine (DFO), despite being detectable in cumulus cells following normal maturation conditions, acute anoxic culture, or in the presence of DFO. Oxygen concentration also significantly altered inner cell mass cell proportions at the blastocyst stage. These results suggest that oxygen can influence gene expression in the bovine embryo during postcompaction development and that these effects may be mediated by HIF2alpha.

230.Novel immune modulation to improve reproductive outcomes in pigs

Early embryonic mortality is a major factor limiting litter size and profitability in the pig industry. Pregnancy success requires an immunologically receptive reproductive tract, generated in response to exposure to immune modulating factors in the seminal plasma (SP). Both the short-term pro-inflammatory response of the endometrium to SP and to a novel immune-modulating product, mycobacterial cell wall extract (MCWE; 'Equimune', Bioniche Animal Health) and the reproductive outcomes from a large-scale farrowing trial are described. In the first experiment, 15 Large White gilts (24 weeks of age) were randomly allocated to three intrauterine treatments administered at onset of gonadotrophin-induced oestrus: (1) 80 mL PBS (control); (2) 80 mL SP; or (3) 80 mL PBS containing 500 �g MCWE. Gilts were slaughtered 32–34 h later and reproductive tracts retrieved. Luminal fluid leukocytes were assessed following fixation using DIFF-Quik stain, and indicated the proportion of lymphocytes increased with SP and MCWE treatment compared to the control group (14.0% and 17.0% v. 9.3%; P < 0.05), and the proportion of monocytes decreased (12.3% and 15.0% v. 25.0%; P < 0.05). In the second experiment, Large White or Large White/Landrace crossbred females (n�=�161) were artificially inseminated twice, following standard industry practice, after detection of standing oestrus. Stratified for parity and breed, each was allocated to a treatment group: (a) Control: standard AI dose 1st and 2nd insemination; (b) 500 μg MCWE added to 2nd insemination; or (c) 500 μg MCWE included in the 1st and 2nd insemination. The overall pregnancy rate was 91%, with no significant effect of treatment on litter size, average piglet bodyweight at birth or litter variability. Although the use of MCWE at the time of AI did not improve reproductive outcome, significant potential remains in utilising its immune stimulating properties in 'priming' the reproductive tract, followed by mating at the next oestrus. This approach may improve gilt farrowing rates, thus increase overall herd productivity and efficiency.

Comparison of oocyte factors and transforming growth factor-beta in the regulation of DNA synthesis in bovine granulosa cells

Oocytes are powerful local modulators of follicular cell functions and many of the activities of oocytes are attributed to members of the transforming growth factor-beta (TGF-beta) superfamily. Whilst in the mouse it is known that members of this family are able to mimic many of the effects of oocytes on follicular cells, the relative importance of any of these factors is unknown in bovine follicles. The objectives of this study were to determine if bovine oocytes express and secrete TGF-beta and to compare oocyte-secreted factor(s) to TGF-beta in terms of their capacities to stimulate mural granulosa cell (MGC) DNA synthesis. Bovine ovaries were collected from an abattoir and RNA was extracted from isolated MGC, cumulus cells, cumulus-oocyte complexes and denuded oocytes (DO). Using RT-PCR, all cell types were found to express TGF-beta1 and TGF-beta2 mRNA transcripts. However, no TGF-beta bioactivity could be detected from DO using a sensitive (40 pg/ml) and specific mink lung fibroblast cell bioassay. MGC were cultured with various combinations and doses of TGF-beta2 and DO for 18 h, followed by a 6-h pulse of [3H]-thymidine as an indicator of cellular DNA synthesis. MGC DNA synthesis was stimulated by both TGF-beta2 and DO. However in response to increasing doses of TGF-beta2, [3H]-thymidine levels plateaued at <2-fold above control levels, whereas levels continued to increase over the dose range of DO tested (up to 3.4-fold). Addition of a TGF-beta pan-specific neutralising antibody to MGC cultures eliminated the TGF-beta2-stimulatory effects on DNA synthesis and the TGF-beta2-suppressive effects on progesterone production, but the antibody was unable to neutralise the same responses when induced by DO. These results support a role for TGF-beta1, TGF-beta2 and DO in paracrine/autocrine regulation of bovine granulosa cell function, but indicate that neither TGF-beta1 nor TGF-beta2 can account for the actions of bovine oocytes on granulosa cells.

Effects of leptin administration and feed restriction on thecal leucocytes in the preovulatory rat ovary and the effects of leptin on meiotic maturation, granulosa cell proliferation, steroid hormone and PGE2 release in cultured rat ovarian follicles

Leptin is expressed by adipocytes and is thought to play a role in regulating food intake and in reproduction. It has been demonstrated that acute leptin administration to immature gonadotrophin-primed rats in vivo inhibits ovulation and causes a decline in food intake. However, feed restriction alone does not inhibit ovulation. Two experiments were designed to investigate the mechanism of leptin-induced inhibition of ovulation. In the first experiment, which was prompted by the importance of ovarian leucocytes in ovulation, the role of leucocytes in leptin-induced inhibition of ovulation was investigated. The second experiment investigated whether high leptin concentrations could inhibit other factors important to ovulation, such as meiotic competence of oocytes, granulosa cell proliferation, steroid or PGE(2) release, and interleukin 1beta production, in vitro. In the first experiment, the populations of neutrophils and monocytes-macrophages in the preovulatory follicles of gonadotrophin-primed, leptin-treated and -untreated rats were examined. A decrease in food intake, as a result of either leptin treatment or feed restriction, specifically reduced the numbers of neutrophils and monocytes-macrophages infiltrating the theca interna of preovulatory follicles without affecting the numbers found in the stroma. The findings show that reduced infiltration of thecal neutrophils and macrophages into preovulatory follicles is a response to reduced food intake. Furthermore, this reduction is not the direct cause of the leptin-induced inhibition of ovulation. In the second experiment, ovarian follicles were cultured for 4 or 12 h in the presence or absence of the following hormones: FSH (500 miu), insulin-like growth factor I (IGF-I) (50 ng ml(-1)), LH (100 ng ml(-1)) and leptin (300 ng ml(-1)). The results demonstrated that high concentrations of leptin in follicle culture do not affect meiotic maturation or steroid release, but tend to inhibit release of PGE 2 (although this result was not significant). DNA synthesis in granulosa cells was not inhibited by leptin in FSH- and IGF-I-supplemented culture media. These results are in agreement with previous studies that have shown that leptin inhibits the stimulatory effects of IGF-I on FSH-stimulated oestradiol production in rat granulosa cells without affecting progesterone production. In summary, leptin does not appear to have an adverse effect on the components of ovulation tested in this study, and therefore must impact on the ovulatory cascade in a way that remains to be defined.

Effects of leptin administration and feed restriction on thecal leucocytes in the preovulatory rat ovary and the effects of leptin on meiotic maturation, granulosa cell proliferation, steroid hormone and PGE2 release in cultured rat ovarian follicles

Leptin is expressed by adipocytes and is thought to play a role in regulating food intake and in reproduction. It has been demonstrated that acute leptin administration to immature gonadotrophin-primed rats in vivo inhibits ovulation and causes a decline in food intake. However, feed restriction alone does not inhibit ovulation. Two experiments were designed to investigate the mechanism of leptin-induced inhibition of ovulation. In the first experiment, which was prompted by the importance of ovarian leucocytes in ovulation, the role of leucocytes in leptin-induced inhibition of ovulation was investigated. The second experiment investigated whether high leptin concentrations could inhibit other factors important to ovulation, such as meiotic competence of oocytes, granulosa cell proliferation, steroid or PGE(2) release, and interleukin 1beta production, in vitro. In the first experiment, the populations of neutrophils and monocytes-macrophages in the preovulatory follicles of gonadotrophin-primed, leptin-treated and -untreated rats were examined. A decrease in food intake, as a result of either leptin treatment or feed restriction, specifically reduced the numbers of neutrophils and monocytes-macrophages infiltrating the theca interna of preovulatory follicles without affecting the numbers found in the stroma. The findings show that reduced infiltration of thecal neutrophils and macrophages into preovulatory follicles is a response to reduced food intake. Furthermore, this reduction is not the direct cause of the leptin-induced inhibition of ovulation. In the second experiment, ovarian follicles were cultured for 4 or 12 h in the presence or absence of the following hormones: FSH (500 miu), insulin-like growth factor I (IGF-I) (50 ng ml(-1)), LH (100 ng ml(-1)) and leptin (300 ng ml(-1)). The results demonstrated that high concentrations of leptin in follicle culture do not affect meiotic maturation or steroid release, but tend to inhibit release of PGE 2 (although this result was not significant). DNA synthesis in granulosa cells was not inhibited by leptin in FSH- and IGF-I-supplemented culture media. These results are in agreement with previous studies that have shown that leptin inhibits the stimulatory effects of IGF-I on FSH-stimulated oestradiol production in rat granulosa cells without affecting progesterone production. In summary, leptin does not appear to have an adverse effect on the components of ovulation tested in this study, and therefore must impact on the ovulatory cascade in a way that remains to be defined.

Mouse oocyte mitogenic activity is developmentally coordinated throughout folliculogenesis and meiotic maturation

Oocytes secrete soluble factors that regulate the growth and differentiation of follicular cells, including maintenance of the distinctive cumulus cell phenotype. This study determines whether the mitogenic activity of oocytes is developmentally regulated and examines the responsiveness of follicular cells to oocytes at different stages of follicular development. Prepubertal SV129 mice of varying ages were primed with 5 IU equine chorionic gonadotropin (eCG) and oocytes/zygotes collected either 46 h post-eCG (immature oocytes), 12 h after administration of 5 IU human CG (hCG; ovulated ova), or 12 h post-hCG and mating (zygotes). Mural granulosa cells (MGC) from antral follicles and GC from preantral follicles were cultured +/- denuded oocytes (DO) for 18 h, followed by a 6-h pulse of [(3)H]thymidine as an indicator of cellular DNA synthesis. Coculturing MGC with meiotically maturing oocytes led to a dose-dependent increase in [(3)H]thymidine incorporation (20-fold above control levels at 0.5 DO/microl). However, [(3)H] counts remained unchanged from control levels when cultured with meiotically incompetent DO from 11- to 15-day-old mice (3% germinal vesicle breakdown; GVB), irrespective of dose of DO or developmental status of GC (MGC or preantral GC). In some treatments, spontaneous meiotic resumption of competent oocytes was prevented by culturing with 5 microM milrinone, a selective inhibitor of oocyte-specific cyclic nucleotide phosphodiesterase. The mitogenic capacity of oocytes was found to decline during and after oocyte maturation. [(3)H]Thymidine incorporation in MGC was highest (11-fold above controls) when cultured with meiotically inhibited (milrinone-treated) GV DO, stimulated 5.5-fold by culture with maturing oocytes, 3-fold with ovulated ova, and unstimulated by zygotes. [(3)H]Thymidine incorporation in MGC was not altered by the dose of milrinone, either in the presence or absence of DO. Metaphase I marked the beginning of the decline in the capacity of oocytes to promote MGC DNA synthesis. These results demonstrate that the capacity of oocytes to promote proliferation of granulosa cells follows a developmental program, closely linked to oocyte meiotic status, increasing with the acquisition of meiotic competence and declining during and after oocyte maturation.

Effects of maternal age on oocyte developmental competence

The widespread use of a variety of assisted reproductive technologies has removed many of the constraints that previously restricted mammalian reproduction to the period between onset of puberty and reproductive senescence. In vitro embryo production systems now allow oocytes from very young animals to undergo fertilization and form embryos capable of development to normal offspring, albeit at somewhat reduced efficiencies compared to oocytes from adult females. They also can overcome infertility associated with advanced age of animals and women. This review examines oocyte developmental competence as the limiting factor in applications of assisted reproductive technologies for both juvenile and aged females. Age of oocyte donor is a significant factor influencing developmental competence of the oocyte. Age-related abnormalities of oocytes include a) meiotic incompetence or inability to complete meiotic maturation resulting in oocytes incapable of fertilization; b) errors in meiosis that can be compatible with fertilization but lead to genetic abnormalities that compromise embryo viability; and c) cytoplasmic deficiencies that are expressed at several stages of development before or after fertilization. In general, oocytes from juvenile donors and the embryos derived therefrom appear less robust and may be less tolerant to suboptimal handling and in vitro culture conditions than are adult oocytes. Research to identify specific cytoplasmic deficiencies of juvenile oocytes may enable modifications of culture conditions to correct such deficiencies and thus enhance developmental competence. Use of oocytes from aged donors for assisted reproduction can have a variety of applications such as extending the reproductive life of individual old females whose offspring still have high commercial value, and conservation of genetic resources such as rare breeds of livestock and endangered species. In general, female fertility decreases with advancing age. Studies of women in oocyte donation programs have established reduced oocyte competence as the major cause of declining fertility with age, although inadequate endometrial function can also be a contributing factor. Most research has emphasized the importance of chromosomal abnormalities because of the well established increase in aneuploidy with increasing maternal age but little is known about the underlying cellular and molecular mechanisms. Research aimed at identifying the specific developmental deficiencies of oocytes from juvenile donors and abnormalities of oocytes from aged females will assist in overcoming present bottlenecks that limit the efficiency of assisted reproduction technologies. Such research will also be crucial to the development of new oocyte-based technologies for overcoming infertility and possibly subverting chromosomal abnormalities in women approaching menopause.

Growth-inhibitory effects of CD40 ligand (CD154) and its endogenous expression in human breast cancer

CD40 binding produces multifaceted growth signals in normal and malignant B cells, whereas its physiological role is less well characterized in epithelial cancers. We examined the growth outcome of CD40 ligation in human breast cancer cells, using CD40+ (T47D and BT-20) and CD40-negative (MCF-7, ZR-75-1) cell lines as defined by flow cytometric analysis, immunohistochemistry, and reverse transcription-PCR. Treatment with the soluble recombinant CD40 ligand (CD40L) molecules gp39 or CD40L-trimer significantly reduced [3H]thymidine uptake in BT-20 and T47D cells by up to 40%, but did not affect the growth of CD40-negative MCF-7 or ZR-75-1 cells. Similarly, significant growth inhibition was observed after co-incubation with CD40L-transfected murine L cells (55.0 +/- 8.9%, P < 0.001) that express membrane CD40L constitutively, or with paraformaldehyde-fixed, CD3+ CD40L+ PBLs from three different HLA-mismatched donors (39.7 +/- 3.7%, P < 0.01). Untransfected L cells and non-CD40L-expressing lymphocytes did not produce significant growth inhibition. The in vivo antitumorigenic effects of CD40L were examined using a s.c. severe combined immunodeficient-hu xenograft model. Pretreatment with two different soluble recombinant CD40L constructs (CD40L and gp39) produced similar xenograft growth-inhibitory effects [67 +/- 24% (n = 4), and 65 +/- 14% (n = 8) inhibition, respectively], which were reversed by co-treatment with the CD40L-neutralizing antibody LL48. In vitro analysis indicated that CD40L-induced growth inhibition was accompanied by apoptotic events including cell shrinkage, rounding, and detachment from the adherent T47D culture monolayer. Thirty-one and 27% of gp39-treated T47D and BT-20 cells underwent apoptosis, respectively, as compared with 56 and 65% from the same cell lines after treatment with the Fas agonistic antibody CH-11. An up-regulation of the proapoptotic protein Bax in T47D and BT-20 cells was observed, which indicated that this Bcl-2 family member may contribute to this growth-inhibitory effect. To explore the clinical relevance of CD40L-CD40 interaction, retrospective immunohistochemical analysis was carried to characterize in situ CD40- and CD40L-expression in breast cancer patient biopsies. All of the infiltrating ductal (5 of 5 cases tested) and lobular (4 of 4 cases) breast carcinomas, carcinomas in situ (6 of 6 cases), and mucinous carcinoma tested (1 case) expressed CD40. Varying proportions of tumor cells also expressed CD40L in the majority of infiltrating ductal (3 of 5 cases) and lobular (3 of 4 cases) carcinomas, and carcinomas in situ (4 of 6 cases), as determined by immunohistochemistry and validated by RT-PCR detection of the CD40L message in only CD40L positive-staining cases. Tumor infiltrating mononuclear cells from infiltrating carcinomas and carcinomas in situ expressed CD40 (10 of 10 cases), but less commonly CD40L (1 case of infiltrating lobular carcinoma, 2 cases of carcinoma in situ). Our findings indicate that the CD40 signaling pathway is active in human breast carcinoma cells. However, tumor-infiltrating lymphocytes from primary tumor tissues may be limited in their capacity to directly modulate tumor growth through the CD40L-CD40 loop.

Effect of cell-to-cell contact on in vitro deoxyribonucleic acid synthesis and apoptosis responses of bovine granulosa cells to insulin-like growth factor-I and epidermal growth factor

Follicle development is the result of a balanced ratio between cell proliferation and cell death. Previous studies demonstrated differential mitotic responses to insulin-like growth factor (IGF)-I and epidermal growth factor (EGF) of cumulus cells (CC) and mural granulosa cells (MGC). Because cell-to-cell contact seems to modulate the occurrence of programmed cell death, the present experiments investigated the role of cell association in mediating apoptosis and the mitogenic responses to these growth factors of CC and MGC. Cumulus cells were cultured either as intact cumulus-oocyte complexes (COC) or after dissociation with EGTA + sucrose, in the presence of 50 ng/ml IGF-I, 5 ng/ml EGF, or both. Mural granulosa cells from the same follicles were similarly cultured either as cell aggregates or as dissociated cells. Synthesis of DNA was assessed by measurement of [(3)H]thymidine incorporation during the last 6 h of a 24-h culture in TCM199. Percentages of cells undergoing apoptosis were determined immunohistochemically in intact COC and GC aggregates, before and after dissociation as well as after the culture period. Epidermal growth factor and IGF-I stimulated DNA synthesis in both cell types; however, EGF inhibited the action of IGF-I in intact COC but not in MGC. Compared to nondissociated cells, dissociation resulted in a reduction of the mitogenic response of CC to both growth factors and of MGC to EGF. Unlike the response of intact COC to combined treatment with the two growth factors, dissociated CC displayed additive responses to the two growth factors in combination. Addition of denuded oocytes to cultures of dissociated CC enhanced both basal and growth factor-stimulated DNA synthesis but did not restore the inhibitory effect of EGF on the IGF-I response characteristic of intact COC. A significant proportion of intact MGC aggregates underwent apoptosis after 24 h of culture, while no increase of apoptotic cells was observed in intact COC. A dramatic increase in the percentage of apoptotic cells was observed in both CC and MGC when cell-cell contact was interrupted, and EGF and IGF-I were able to partially prevent its occurrence. Taken together these data showed that CC and MGC exhibit qualitatively and quantitatively different responses to IGF-I when cultured in the presence of EGF both in terms of DNA synthesis and onset of apoptosis. Moreover, the disruption of cell-cell contact was a major factor reducing cell proliferation and inducing apoptosis among both subsets of GC.

Effect of granulocyte-macrophage colony-stimulating factor deficiency on ovarian follicular cell function

Granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine secreted by lymphohaemopoietic and other cell lineages, is known to influence ovarian cyclicity and embryo development. The aim of this study was to examine the effect of GM-CSF on ovarian follicular cell function using GM-CSF-deficient (GM -/-) mice. Immature GM -/- and GM +/+ mice were stimulated with eCG, and cumulus-oocyte complexes and mural granulosa cells were collected 48 h later. Expression of GM-CSF receptor (GM-CSFR) alpha and beta mRNA subunits by cumulus-oocyte complexes and mural granulosa cells was examined using RT-PCR. Cumulus-oocyte complexes from both genotypes were found to express mRNA for the GM-CSFRalpha-subunit only, while the mural granulosa cells expressed both the alpha and beta receptor subunits. Cumulus-oocyte complexes recovered from GM -/- mice had approximately twice the number of cumulus cells per cumulus-oocyte complex than did those of GM +/+ mice (P < 0.05), even though the growth-promoting activity of denuded GM -/- oocytes was found to be equivalent to that of wild-type oocytes. GM-CSF deficiency was associated with marginally increased DNA synthesis in cumulus cells and significantly (P < 0.05) lower progesterone production by mural granulosa cells recovered from GM -/- compared with those recovered from GM +/+ mice. The addition of rec-mGM-CSF in vitro did not affect DNA synthesis in either cell type or progesterone production by mural granulosa cells, irrespective of GM-CSF status. There was no effect of GM-CSF deficiency on the capacity of FSH and insulin-like growth factor I to stimulate DNA synthesis in cumulus-oocyte complexes (approximately 15- and threefold, respectively) and in mural granulosa cells (approximately two- and threefold, respectively). Taken together, these data show that GM-CSF influences events associated with follicular maturation in mice. The effects of GM-CSF are not exerted directly in granulosa or cumulus cells, but appear to be mediated indirectly, perhaps through the agency of steroidogenesis-regulating secretions of local macrophage populations residing in the theca.

Effect of granulocyte-macrophage colony-stimulating factor deficiency on ovarian follicular cell function

Granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine secreted by lymphohaemopoietic and other cell lineages, is known to influence ovarian cyclicity and embryo development. The aim of this study was to examine the effect of GM-CSF on ovarian follicular cell function using GM-CSF-deficient (GM -/-) mice. Immature GM -/- and GM +/+ mice were stimulated with eCG, and cumulus-oocyte complexes and mural granulosa cells were collected 48 h later. Expression of GM-CSF receptor (GM-CSFR) alpha and beta mRNA subunits by cumulus-oocyte complexes and mural granulosa cells was examined using RT-PCR. Cumulus-oocyte complexes from both genotypes were found to express mRNA for the GM-CSFRalpha-subunit only, while the mural granulosa cells expressed both the alpha and beta receptor subunits. Cumulus-oocyte complexes recovered from GM -/- mice had approximately twice the number of cumulus cells per cumulus-oocyte complex than did those of GM +/+ mice (P < 0.05), even though the growth-promoting activity of denuded GM -/- oocytes was found to be equivalent to that of wild-type oocytes. GM-CSF deficiency was associated with marginally increased DNA synthesis in cumulus cells and significantly (P < 0.05) lower progesterone production by mural granulosa cells recovered from GM -/- compared with those recovered from GM +/+ mice. The addition of rec-mGM-CSF in vitro did not affect DNA synthesis in either cell type or progesterone production by mural granulosa cells, irrespective of GM-CSF status. There was no effect of GM-CSF deficiency on the capacity of FSH and insulin-like growth factor I to stimulate DNA synthesis in cumulus-oocyte complexes (approximately 15- and threefold, respectively) and in mural granulosa cells (approximately two- and threefold, respectively). Taken together, these data show that GM-CSF influences events associated with follicular maturation in mice. The effects of GM-CSF are not exerted directly in granulosa or cumulus cells, but appear to be mediated indirectly, perhaps through the agency of steroidogenesis-regulating secretions of local macrophage populations residing in the theca.

Oocyte-secreted factor(s) determine functional differences between bovine mural granulosa cells and cumulus cells

Cumulus cells and mural granulosa cells (MGC) are phenotypically different and there is now evidence suggesting that the oocyte plays an active role in determining the fate of follicular somatic cells. This study investigates the role of oocyte-secreted factor(s) in the regulation of the growth and differentiation of cumulus and MGC. Bovine cumulus-oocyte complexes (COC) and MGC were cultured with various hormones for 18 h followed by a further 6-h pulse of [(3)H]thymidine as an indicator of follicular cell DNA synthesis. The COC incorporated 11 to 14 times more [(3)H]thymidine than MGC in either the absence or presence of 50 ng/ml insulin-like growth factor (IGF)-I. Purified porcine FSH (450 ng/ml) added together with IGF-I marginally increased (3)H incorporation in MGC relative to IGF-I alone but dramatically decreased incorporation in COC sixfold. Conversely, mean progesterone production in the presence of IGF-I + FSH was 13-fold higher from MGC than from COC, confirming a distinctive phenotype of cumulus cells. However, this phenotype was found to be dependent on the presence of the oocyte, as microsurgical removal of the oocyte (oocytectomy) resulted in an 11-fold decrease in [(3)H]thymidine incorporation in cumulus cells treated with IGF-I, elimination of the inhibitory effect of FSH on IGF-I-stimulated DNA synthesis, and led to a 2-fold increase in progesterone production in medium with IGF-I and FSH. All of these markers were completely restored to COC levels when oocytectomized complexes were cocultured with denuded oocytes (DO) at a concentration of 0.5 oocytes/microl, demonstrating that oocytes secrete a soluble factor(s) that promotes growth and attenuates cumulus cell progesterone secretion. In the presence of IGF-I, [(3)H]thymidine incorporation in MGC increased ninefold above control levels with the addition of DO. The addition of FSH to IGF-I-increased (3)H counts in MGC, however, led to a decrease in counts in MGC + DO as is also observed in COC. Furthermore, progesterone production was halved when DO were added to MGC cultures, most notably in the presence of IGF-I and/or FSH. These results provide further evidence that MGC and cumulus cells have distinctive phenotypes and that the oocyte is responsible for some of the characteristic features of cumulus cells. Bovine oocytes secrete a soluble factor(s) that simultaneously promotes growth and attenuates steroidogenesis in follicular somatic cells.

Bovine parthenogenesis is characterized by abnormal chromosomal complements: implications for maternal and paternal co-dependence during early bovine development

The present study was conducted to examine the karyotypes of parthenogenetic bovine embryos arising from the application of standard oocyte activation and diploidization methods. Bovine cumulusoocyte complexes were collected and matured in vitro for 24 hr prior to oocyte activation with either 5 microM ionomycin or 7% ethanol for 5 min. Groups of activated oocytes were further treated with 5 micrograms/ml cytochalasin D or 1.9 mM 6-dimethylaminopurine (DMAP) for 6 hr. Cleavage varied significantly (P < .05) among the treatment groups with 68.0% of the ethanol- and DMAP-treated oocytes dividing. Blastocyst development did not vary with 18.4 +/- 2.5% of all treated oocytes progressing to this stage. Blastocyst development did not occur in groups subjected to oocyte activation alone. Blastocysts displayed haploid (2.3%), diploid (11.4%), tetraploid (40.9%), octaploid (4.5%), and mixoploid chromosomal complements (40.9%). Two-cell stage parthenogenotes resulting from ethanol or ionomycin treatment alone displayed haploid (66.7%), diploid (16.7%), tetraploid (4.2%), and mixoploid (12.5%) complements. Our results demonstrate that diploid bovine parthenogenotes arising from these procedures are a minority, with the majority of parthenogenotes displaying polyploid and mixoploid chromosomal complements. The events contributing to these abnormal chromosomal complements occur as early as completion of the first cell cycle, possibly linking these events with the absence of a paternally supplied centrosome.

The in vivo and in vitro effects of exogenous leptin on ovulation in the rat

Leptin, a hormonal product of the Lep gene, is expressed by adipocytes and is thought to play a role in regulating food intake and reproduction. The leptin protein has been localized in many reproductive tissues, including the ovary. Several publications indicate that the ovary is directly affected by leptin and that leptin may be a factor linking obesity and reproductive dysfunction. In this study, the effect of systemic leptin administration on ovulation in the rat ovary, both in vivo and in vitro, was investigated. Ip administration of leptin (30 microg at 3 hourly intervals for 15 h) to immature gonadotropin-primed rats caused a decline in ovulation in vivo, from 15.9+/-2.0 oocytes in the control animals to 5.3+/-1.6 oocytes in the leptin-treated animals (P < 0.001). Plasma progesterone and estradiol levels were analyzed immediately before ovulation, and neither was altered significantly in animals receiving the leptin treatment. Food consumption and body weight decreased following leptin treatment; however, a loss in body weight alone (pair-fed controls) was insufficient to explain the decrease in ovulation observed in the leptin-treated animals. In vitro perfusion of FSH-primed whole ovaries showed that treatment with leptin in combination with LH significantly decreased ovulations from 5.7+/-1.6 per ovary perfused with LH alone to 1.3+/-0.6 in those with LH and 1 microg/ml leptin (P < 0.05). Progesterone and estradiol levels in the samples taken during the perfusion period were unaffected by leptin treatment. In summary, leptin administration resulted in fewer ovulations, both in vivo and in vitro, but did not influence steroid levels. Systemic leptin administration at these doses can therefore inhibit ovulation, a process that occurs through a direct effect on the ovary.

Differential regulation by FSH and IGF-I of extracellular matrix IGFBP-5 in bovine granulosa cells: effect of association with the oocyte

Inhibition of insulin-like growth factor (IGF)-I induced DNA synthesis in bovine oocyte-cumulus complexes (OCCs) caused by follicle-stimulating hormone (FSH) has been linked to changes in the extracellular matrix which do not occur in mural granulosa cells (MGCs). We investigated regulation by IGF-I and FSH of secreted and extracellular matrix entrapped IGF-binding proteins. OCCs and MGCs from bovine ovaries were cultured in media supplemented with IGF-I and FSH for 24 h. Culture media and extracellular matrix were analysed for IGF-binding proteins by Western ligand blot and immunoblot and found to contain principally IGFBP-3 and -5. The combined treatment of IGF-I and FSH increased the concentration of IGFBP-3 in OCC and MGC conditioned media by 4- and 6-fold, respectively. Treatment of OCCs and not MGCs with IGF-I and FSH together increased extracellular matrix IGFBP-5 by 2.5-fold. The differential regulation of extracellular matrix IGFBP-5 in OCCs compared to MGCs suggest involvement of changes in the extracellular matrix brought about by IGF-I and FSH in overall regulation of IGF-I in the ovarian follicle.

Comparative analysis of calf and cow oocytes during in vitro maturation

To determine possible causes of reported differences between developmental competence of oocytes isolated from prepubertal (10- to 14-week-old calves) and adult cows, three parameters were analysed, comparatively, during in vitro maturation (IVM): (1) oocyte diameter, (2) oocyte energy metabolism, and (3) protein synthesis of oocytes and cumulus cells. Cumulus-oocyte complexes were isolated from follicles of 3-5 mm in diameter in both age groups. Mean oocyte diameter was smaller (P < 0.02) in calves than in cows (118.04 +/- 1.15 versus 122.83 +/- 0.74 microns). During the first 3 hr of IVM, calf oocytes metabolised glutamine and pyruvate at lower rates than adult oocytes, but after 24 hr of culture, both molecules were metabolised at the same rate as for adult oocytes. A significant decrease in protein synthesis, as measured by [35S]methionine and [35S]cysteine incorporation was recorded after 9 hr of IVM in calf oocytes, while in adult oocytes a significant decrease in protein synthesis was detected only after 24 hr. After the first 3 hr of maturation, proteins of 130, 26, and 24 kDa were more abundant in adult than in calf oocytes, while a protein of 55 kDa was more visible in calf than in adult oocytes. At the same time, among proteins newly synthesised by cumulus cells, molecules of 405, 146, 101, and 77 kDa were more abundant in adults than in calves. In conclusion, calf oocytes and cumulus cells showed several differences when compared with their adult counterparts, which are consistent with their reported lower developmental competence.

The in vitro developmental competence of bovine oocytes can be related to the morphology of the ovary

This study was designed to assess whether the developmental potential of bovine cumulus-oocyte complexes (COCs) could be related to the morphology of their originating ovary, providing a simple, noninvasive and objective selection criterion. Ovaries were divided into 3 categories on the basis of: A) presence of a follicle > 10 mm in diameter, B) presence of more than 10 follicles of 2 to 5 mm in diameter and no follicles > 10 mm, and C) presence of less than 10 follicles of 2 to 5 mm in diameter and no follicles > 10 mm. The COCs, isolated from ovaries of Category C, showed lower rates of maturation and blastocyst formation than those from Categories A and B. Moreover, blastocysts derived from Category C ovaries had fewer cells than those derived from the other 2 categories. It is concluded that ovarian morphology is a simple and noninvasive parameter for an effective selection of oocytes with better developmental competence.

Interactions between follicle-stimulating hormone and growth factors in regulation of deoxyribonucleic acid synthesis in bovine granulosa cells

Follicle growth is regulated by the combined actions and interactions of pituitary gonadotropic hormones and local intraovarian paracrine and/or autocrine agents, including the peptide growth factors, insulin-like growth factor-I (IGF-I), and epidermal growth factor (EGF). The present study was undertaken to determine a) whether the previously demonstrated inhibitory effect of FSH on DNA synthesis was related to its ability to cause cumulus mucification as a differentiated response incompatible with continued proliferation, and b) whether increased IGF-binding proteins (IGFBP) secreted in response to FSH competed with IGF receptors, thereby inhibiting response to exogenous IGF-I. To determine the effects of cumulus mucification in modulating the mitogenic response to IGF-I, two other agents that induce cumulus mucification by different mechanisms, EGF and dibutyryl cAMP (dbcAMP), were compared with FSH. To determine the possible role of IGFBP in modulating the mitogenic response to IGF-I, an IGF-I analogue that does not bind to IGFBP, long arg3-IGF-I (LR3-IGF-I), was compared with native IGF-I for efficacy in stimulating DNA synthesis in the absence and presence of each of the above agonists. Both IGF-I and LR3-IGF-I stimulated [3H]thymidine incorporation in cumulus cells to a much greater extent than in mural granulosa cells. Incorporation in mural cells was increased by each of FSH, EGF, and dbcAMP acting by itself, and in most instances was considerably enhanced by the combined action of these agents with each of the IGF-I forms. In contrast, the considerably greater stimulatory effect of both IGF-I and LR3-IGF-I on cumulus cells was markedly decreased by each of FSH, EGF, and dbcAMP. These findings suggest that the inhibition of IGF-I-stimulated DNA synthesis in cumulus cells is a consequence of induction of cumulus cell differentiation (mucification) by FSH and EGF rather than through competition between IGF-I receptor and IGFBP secretion induced by these agents.

Effects of using vasectomized bulls in artificial insemination practice on the reproductive efficiency of Italian buffalo cows

The effects of the presence or absence of vasectomized male buffaloes on the reproductive efficiency of buffalo cows (n = 396) undergoing artificial insemination (AI) was studied on six farms owned and operated by a single consortium. Lactating animals were separated into two groups of various sizes on each farm and kept under semi-range conditions. Vasectomized bulls were present in one group at a bull/empty-cow ratio of 1:30. No bulls were present in the other group. Reproductive efficiency between the two groups over a period of 3.5 months was compared and evaluated on the basis of: 1) the number of spontaneous overt estruses associated with either feeble or intense signs of estrous behaviour; 2) the number of functional estrous cycles, i.e. estrous cycles with luteal phases defined as normal, based on specified progesterone concentrations in milk or blood plasma 8-10 days after estrus; 3) the number of consecutive functional estrous cycles in cases of induced estrus; and 4) pregnancy rate. Groups with bulls present demonstrated a significantly higher reproductive efficiency than groups without them. There was a higher incidence of spontaneous estrus (92 versus 69%; P < 0.01); spontaneous estrus of high intensity (62.2 versus 31.1%; P < 0.01); and higher incidence of functional estrous cycles following both spontaneous (65.8 versus 57.1%) and induced (77.0 versus 59.5%; P < 0.05) estrus. Exposure to vasectomised bulls also increased the incidence of consecutive functional estrous cycles (90.5 versus 68.1%; P < 0.01), and the pregnancy rate in cows inseminated at spontaneous (42.5 versus 18.9%; P < 0.01) or induced (51.1 versus 33.3%; P < 0.05) estrus. Overall pregnancy rate did not differ significantly between cows inseminated at induced or spontaneous estrus, although in the absence of bulls, pregnancy rate per AI was higher in cows inseminated at induced than at spontaneous estrus (33.3 versus 18.9%).

Insulin-like growth factor-1, a component of serum that enables porcine cumulus cells to expand in response to follicle-stimulating hormone in vitro

The present study was aimed at determining whether insulin-like growth factor-1 (IGF-1) is a component of fetal bovine serum (FBS) that enables porcine cumulus cells to expand in response to FSH in vitro. Cumulus-oocyte complexes (COC) obtained from 4- to 6-mm follicles of prepubertal gilts were cultured at 39 degrees C for 24 h in media that contained human recombinant IGF-1 (50 ng/ml), FBS (15% v:v), or their combination, with or without FSH (1.5 microg/ml), and cumulus expansion was scored microscopically. Expansion was FSH dependent and was observed only when IGF-1, FBS, or both were present. The proportion of FSH-stimulated COC exhibiting full expansion in response to IGF-1 alone did not differ significantly (p > 0.05) from the proportion in those cultured with FBS or IGF-1+FBS (79 +/- 2.8% vs. 84 +/- 2.2% or 76 +/- 6.2%, respectively). In a concentration-response study, FSH-stimulated expansion was observed in a significant proportion of COC (32 +/- 2.8% vs. 0% control) at 1 ng/ml IGF-1, with the proportions increasing dose-dependently to maximal values between 10 and 75 ng/ml IGF-1, and decreasing at higher IGF-1 concentrations. Exposure of COC to an IGF-1 receptor (IGF-1R)-neutralizing antibody (Ab) for 90 min before addition of FSH and FBS dose-dependently inhibited cumulus expansion, with maximal inhibition at 10 microg/ml (1 +/- 1.0% vs. 68 +/- 1.1% control). In the absence of FBS or IGF-1, some COC had a tendency toward slight expansion when cultured with FSH, and the Ab completely inhibited that effect, suggesting that this may be due to endogenous IGF-1 production by the COC. The Ab effect was reversible and was eliminated by washing twice with fresh medium followed by culture for an additional 24 h in the presence of FSH and FBS. Expression of IGF-1R mRNA in the isolated oocyte and cumulus cells was determined by reverse tramscriptase polymerase chain reaction using sequence-specific primers. The IGF-1R message was detected in both the oocyte and cumulus cells. Collectively, these observations suggest that IGF-1 is a component of serum that enables cumulus cells to expand in response to FSH in vitro, and that the effect is receptor mediated. Since IGF-1 is present in the follicle in vivo, it may have a physiological role during gonadotropin-induced cumulus expansion.

Bovine oviductal and embryonic insulin-like growth factor binding proteins: possible regulators of "embryotrophic" insulin-like growth factor circuits

Bovine oviductal monolayer and vesicle primary cultures express insulin-like growth factor (IGF)-I and -II mRNAs and polypeptides. Early bovine embryos also express IGF-I, IGF-II, IGF-I receptor, IGF-II receptor, and insulin receptor mRNAs. This study reports the expression of IGF binding protein (IGFBP) mRNAs and polypeptides in bovine oviduct primary cultures and IGFBP mRNAs in preattachment embryos. Release of immunoreactive IGF-I and IGF-II by oviduct cultures and bovine blastocysts was also determined. IGFBP-2, -3, -4, and -5 transcripts were observed in oviduct primary cultures throughout an 8-day interval. IGFBP-1 and -6 mRNAs were consistently not detected in the oviduct. Messenger RNAs encoding IGFBPs -2, -3, and -4 were detected throughout bovine preattachment development, while transcripts encoding IGFBP-5 were detected only in blastocysts. IGFBP-1 and -6 transcripts were not detected in early embryos. Ligand blot analysis with 125I-labeled IGF-II revealed the presence of four prominent polypeptide bands of approximate molecular masses 24, 31, and 36 kDa, and a broad band extending from 46 to 53 kDa, in conditioned media samples prepared from oviduct primary cultures. Western immunoblot analysis confirmed the identity of the 24-kDa, 31-kDa, and 36-kDa species as IGFBP-4, -5, and -2, respectively. Levels of the release of IGF-II from oviductal vesicle cultures were significantly greater than levels observed for monolayer cultures (p < 0.005). No significant difference in the levels of IGF-I release between monolayer and vesicle cultures was observed. Pools of 10 blastocysts released on average 36.2 +/- 3.9 pg of IGF-II per embryo, while the release of embryonic IGF-I was below the levels of detection for our assay. The results suggest that maternally derived IGF may be regulated by IGFBPs to support bovine preattachment development.

Effects of epidermal growth factor and follicle-stimulating hormone during in vitro maturation on cytoplasmic maturation of porcine oocytes

The present study was undertaken to investigate the influence of epidermal growth factor (EGF) and follicle-stimulating hormone (FSH) during in vitro maturation on cytoplasmic maturation of porcine oocytes as revealed by the success of fertilization and by the changes in the pattern of protein synthesis in oocytes and cumulus cells. For fertilization studies, oocyte-cumulus cell complexes (OCC) were cultured in media containing human recombinant EGF (1 ng/ml) or FSH (1.5 microg/ml) or both for 44 hr prior to fertilization with fresh sperm for 6-8 hr. The oocytes were then fixed, stained, and examined as whole mounts following an additional 14 hr of culture. Addition of EGF, FSH, and EGF + FSH significantly increased the proportion of oocytes reaching MII stage. The addition of EGF alone significantly decreased the percentage of polyspermic oocytes and increased the proportion of monospermic oocytes forming 2 normal pronuclei. FSH abolished these effects of EGF and significantly increased the percentage of polyspermic oocytes forming more than 2 pronuclei when added alone or with EGF. For protein analysis, OCC were cultured in media containing the above hormones for 6, 24, and 44 hr and exposed to 0.5 mCi/ml L-[35S]methionine during the last 3 hr of cultures. The oocytes and cumulus cells were separated prior to lysis in SDS sample buffer, and denatured polypeptides were separated by 1-dimensional SDS-PAGE. In the oocyte, addition of EGF and FSH alone stimulated the synthesis of 34, 45, and 97 kDa proteins after 6 hr of culture; however, the addition of EGF and FSH together was without any effect. After 24 hr, EGF alone inhibited the synthesis of these peptides, whereas FSH alone and with EGF maintained the stimulation of synthesis of 34 and 45 kDa proteins. Two additional peptides corresponding to 66 and 200 kDa appeared at this time as a result of exposure to FSH alone or with EGF. After 44 hr of culture, these 2 new peptides were observed in all groups and the stimulatory effect of FSH and FSH + EGF was still evident. An additional peptide of 26 kDa appeared at this time as a result of FSH and EGF + FSH treatments. In the cumulus cells, EGF and FSH each alone induced the synthesis of a new peptide of 26 kDa after 6 hr of culture. FSH when added alone or with EGF induced the synthesis of an additional peptide of 29 kDa, the synthesis of which remained unchanged at 24 and 44 hr. After 24 hr, FSH alone and in combination with EGF induced the synthesis of an additional 38 kDa peptide and its synthesis was still maintained at 44 hr. EGF alone had no effect on protein synthesis in cumulus cells at 24 and 44 hr. These studies indicate that EGF may have a physiological role in the regulation of cytoplasmic maturation of porcine oocytes.

Advances in production of embryos in vitro from juvenile and prepubertal oocytes from the calf and lamb

The use of juvenile donors in embryo-transfer (ET) programmes offers considerable potential for accelerated genetic gain in domestic livestock through reduced generation interval. The present paper reviews recent research aimed at optimizing embryo production from oocytes collected from young calves and lambs using in vitro methods of embryo production. Emphasis is placed on criteria for donor selection, oocyte-collection methods, and hormone-stimulation methods designed to produce maximum yields of viable oocytes. In vitro fertilization (IVF) rates of calf and lamb oocytes did not differ significantly whether matured in vivo or in vitro, and rates of development of blastocyst stages in culture were similar to those observed for embryos derived from adult donors. Blastocysts produced by IVF of lamb and calf oocytes established ET pregnancies at rates of 30-45%. Pregnant recipients have reached full term and delivered normal offspring at rates similar to those expected following ET of embryos produced in vivo from superovulated donors. On the basis of current follicle-stimulation protocols, on rates of blastocyst production in vitro under optimal conditions, and on observed pregnancy rates from fresh transfer of IVF embryos, 8-10 pregnancies may be expected per oocyte collection from 10-12-week-old calves and from 6-8-week-old lambs.

Effect of estrogen-treated porcine ampulla oviductal epithelial cells on early embryonic development in vitro and characterization of their protein synthetic activity

Recent studies by Buhi et al. have demonstrated that estrogen (E2) is responsible for the induction of de novo synthesis and secretion of certain oviductal secretory proteins (OSP) and inhibition of other OSP in porcine oviductal explant cultures. The present work was undertaken to evaluate the effect of E2-treated oviductal epithelial cell coculture on the development of early porcine embryos derived from in vitro matured and fertilized oocytes. In vitro synthesis of secretory proteins by E2-treated oviductal cells used for coculture was also investigated by one-dimensional (1D) and two-dimensional (2D) sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE). The results showed that the cleavage rate was significantly enhanced by coculturing fertilized eggs with E2-treated oviductal epithelial cells. The in vitro protein synthetic pattern of oviductal secretory proteins was influenced by E2 treatment. These variations included the disappearance of one protein (82,000 M(r)) and the appearance of another (33,000 M(r)) in the E2-treated group as assessed by 1D-SDS-PAGE. Additional proteins of M(r) 97,000 and an M(r) 36,000-45,000 complex were increased in abundance by the E2 treatment. Analyses by 2D-SDS-PAGE revealed three major E2-dependent proteins, of M(r) 45,000 (pI 5.5), 43,000 (pI 5.5) and a 36,000-45,000 M(r) (pI 4.8) protein complex, whereas polypeptides of M(r) 97,000 (pI 5.1), 36,000 (pI 8.0) and 25,000 (pI 6.8) were inhibited by E2 treatment. The results demonstrated that porcine epithelial cell protein synthetic patterns are influenced by E2 treatment and that estradiol treatment of oviductal cells may increase the rate of zygote cleavage during early development in vitro in pigs.

Expression of urokinase-type plasminogen activator in human preimplantation embryos

During embryo implantation in the human trophoblast cells invade the endometrium and plasminogen activators (PA) are implicated in this tissue invasion process. Our studies on surplus embryos from patients undergoing in-vitro fertilization (IVF) treatments showed that PA activity was present in secretions of blastocysts but not embryos at the 2-4-cell stage. The secretion of this PA activity by blastocysts was increased by the addition of epidermal growth factor (EGF) to the embryo cultures. This PA activity had a molecular weight similar to that of urokinase-type PA (uPA). The mRNA for uPA was present in blastocysts, as determined by the reverse-transcription and polymerase chain reaction (RT-PCR) technique. These data indicate that uPA is produced by human preimplantation embryos and may play a role in early human development and embryo implantation.

Expression of insulin-like growth factors in two bovine oviductal cultures employed for embryo co-culture

We have investigated the patterns of expression and cellular localization of polypeptides and mRNAs encoding IGF-I and IGF-II in intact bovine oviduct and two bovine oviductal primary cultures (monolayers and vesicles) which are utilized for supporting development in vitro. IGF-I and IGF-II polypeptides were localized by immunocytochemistry in intact oviduct and in both primary cultures for an 8-day culture interval, but IGF-II polypeptide displayed a more restricted distribution in day 8 monolayer cultures. IGF-I and IGF-II mRNAs were localized in both oviductal cell cultures as assessed by in situ hybridization. We were unable to detect IGF-I and IGF-II mRNAs in intact oviduct by in situ hybridization; however, transcripts encoding IGF-I and IGF-II mRNAs were detected in intact oviduct cell preparations and all primary culture samples by reverse transcription-PCR methods. The origin and phenotypic stability of these cultures was assessed by immunostaining with antibodies raised against vimentin (mesenchymal cell marker) and cytokeratin (epithelial cell marker). Over the culture period, the proportion of vimentin-immunoreactive cells increased in the monolayer cultures but remained at a low level in the vesicle cultures which were predominantly composed of cytokeratin-positive cells. The results suggest that oviductal cell co-culture may facilitate early mammalian development, in part, by the establishment of paracrine growth factor circuits.

Role of germinal vesicle on protein synthesis in rat oocyte during in vitro maturation

To investigate the role of the germinal vesicle (GV) on in vitro maturation (IVM) of rat oocytes, we examined protein synthesis during IVM by comparing polypeptide patterns in control and enucleated oocytes using one and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Separation of polypeptides extracted from the cytoplasm of GV by one-dimensional SDS-PAGE revealed that a 55 kDa polypeptide was present only in the GVs of rat oocytes. At 0, 12, 24, 36, and 44 hr after PMSG injection, prior to the initiation of maturation, enucleated oocytes synthesized the same major polypeptides as cumulus intact (CI) oocytes. During meiotic maturation, no major changes were detected in protein synthesis from prophase (GV stage) to prometaphase I (0-6 hr IVM). However, after entry into prometaphase I (7 hr IVM), striking changes were seen; a 24 kDa polypeptide disappeared and expression of a 34 kDa polypeptide became stronger. This pattern lasted until metaphase II. We detected no major differences in the pattern of protein synthesis between CI and enucleated oocytes using two-dimensional PAGE. These results indicate that protein synthesis in the maturing rat oocyte is controlled by cytoplasmic regulators rather than intrinsic nuclear components.

Differential effects of insulin-like growth factor-I and follicle-stimulating hormone on proliferation and differentiation of bovine cumulus cells and granulosa cells

Effects of gonadotropins and peptide growth factors on 3H-thymidine incorporation, as an indicator of proliferation of granulosa cells and cumulus cells from bovine ovarian follicles during in vitro culture, were determined. Incorporation of 3H-thymidine in cumulus cells during 24-h culture in protein-free medium was about 100-fold greater than in granulosa cells from small follicles. Small but significant (p < 0.05) increases in incorporation of 3H-thymidine in cumulus cells (2.5-fold), but not in granulosa cells, resulted from addition of FSH, LH, or epidermal growth factor to culture media. Much larger, highly significant (p < 0.01) increases in 3H-thymidine incorporation resulted from exposure of both cumulus cells (18-fold) and granulosa cells (6-fold) to insulin-like growth factor-I (IGF-I). Addition of IGF-I together with FSH resulted in additive increases in 3H-thymidine incorporation in granulosa cells over a wide range of each agonist. In contrast, addition of FSH markedly decreased the stimulatory effect of a maximally effective concentration of IGF-I on incorporation in cumulus cells. Addition of estradiol, either alone or with IGF-I, had no consistent effect on 3H-thymidine incorporation in either cumulus cells or granulosa cells. Differentiated functions of cumulus and granulosa cells, including cumulus expansion (an indicator of hyaluronic acid secretion) and progesterone secretion, were investigated under the same culture conditions. FSH was highly effective in stimulation of cumulus cell expansion, with maximal expansion occurring at the lowest concentration tested (0.04 micrograms/ml). LH was effective only at considerably higher concentrations consistent with degree of contamination with FSH. IGF-I was ineffective in inducing cumulus expansion, either alone or together with FSH. FSH and IGF-I by themselves each stimulated progesterone secretion by both cumulus and granulosa cells, with further additive stimulatory effects by the two agents in combination. On a per cell basis, cumulus cells produced considerably more progesterone than granulosa cells under both basal and hormone-stimulated conditions. The results suggest that IGF-I has a dual role in follicle regulation--that it acts additively with FSH as an autocrine regulator of granulosa cell growth and, in the absence of FSH, as a paracrine regulator of cumulus cell proliferation in small antral follicles. The effect of FSH, by inducing cumulus expansion, may terminate further cumulus cell proliferation before ovulation.