Possible involvement of CD81 in acrosome reaction of sperm in mice

Tetraspanin CD81 is closely homologous in amino acid sequence with CD9. CD9 is well known to be involved in sperm-egg fusion, and CD81 has also been reported to be involved in membrane fusion events. However, the function of CD81 as well as that of CD9 in membrane fusion remains unclear. Here, we report that disruption of the mouse CD81 gene led to a reduction in the fecundity of female mice, and CD81-/- eggs had impaired ability to fuse with sperm. Furthermore, we demonstrated that when CD81-/- eggs were incubated with sperm, some of the sperm that penetrated into the perivitelline space of CD81-/- eggs had not yet undergone the acrosome reaction, indicating that the impaired fusibility of CD81-/- eggs may be in part caused by failure of the acrosome reaction of sperm. In addition, we showed that CD81 was highly expressed in granulosa cells, somatic cells that surround oocytes. Our observations suggest that there is an interaction between sperm and CD81 on somatic cells surrounding eggs before the direct interaction of sperm and eggs. Our results may provide new clues for clarifying the cellular mechanism of the acrosome reaction, which is required for sperm-egg fusion.

Allorecognition in urochordates: identification of a highly variable complement receptor-like protein expressed in follicle cells of Ciona

The evolutionary origin of allorecognition in vertebrates is unknown. Urochordates, being the closest living relatives of vertebrates [Delsuc F, Brinkmann H, Chourrout D, Philippe H]. Tunicates and not cephalochordates are the closest living relatives of vertebrates. Nature 2006; 439: 965-8], have efficient mechanisms to prevent both allogeneic fusion and self fertilization. To shed light on allorecognition in urochordates and on the molecules involved in preventing self fertilization, we compared gonadal cDNAs of three genetically unrelated Ciona intestinalis individuals by suppression subtractive hybridisation (SSH). Here, we report the discovery and characterization of a highly polymorphic gene coding for a transmembrane protein with several short consensus repeat domains (SCR/CCP). The protein, termed variable complement receptor-like 1 (vCRL1), is structurally similar to vertebrate complement receptors. However, in contrast to vertebrate complement receptors, vCRL1 shows an unprecedented high degree of amino acid variations among Ciona individuals and is expressed in follicle cells as well as in hemocytes. Based on our data we propose that in the absence of MHC Ciona uses variable components of the complement system as individuality markers.

Immunolocalization of the hepatocyte growth factor (HGF) system in the rat ovary and the anti-apoptotic effect of HGF in rat ovarian granulosa cells in vitro

Hepatocyte growth factor (HGF) regulates granulosa cell (GC) steroidogenesis and suppresses apoptosis in non-ovarian cells. The hypothesis was thus developed that intraovarian HGF supports folliculogenesis by mediating steroidogenesis and suppressing apoptosis. To investigate the latter, the anti-apoptotic actions of HGF were tested in GCs and follicles isolated from immature rats. Results showed that HGF suppressed apoptosis in GC and follicle cultures as visualized using apoptosis indicator dye, YO-PRO-1. Immunohistochemistry was used to investigate the distribution of HGF, c-met, and HGF activator (HGFA) protein during folliculogenesis in equine chorionic gonadotropin (eCG)-primed rats. Immunoreactive HGF content was the greatest in GCs within preantral follicles. Following eCG, large antral follicles showed elevated HGF staining in theca and interstitial cells when compared with GCs. Intense c-met staining was observed in GCs within non-primed small preantral follicles; following eCG, the level of c-met was diminished in GCs, but increased within theca and interstitial cells. Theca, interstitium, and GCs in non-primed and primed ovaries contained HGFA. Following eCG, HGFA was more apparent in theca cells and the interstitium when compared to that in GCs within large antral follicles. The presence of HGF, c-met, and HGFA in preantral follicles would potentially enable the anti-apoptotic effects of HGF that were observed in vitro to occur in vivo. Advanced folliculogenesis led to a change in the cellular distribution of the HGF, c-met, and HGFA, suggesting that the ovarian HGF system is hormonally regulated in vivo.

Microscopic characterization of follicular structures in letrozole-induced polycystic ovarian syndrome in the rat

BACKGROUND

Our objective was to characterize the tissular distribution of relevant cytoskeletal proteins, cellular adhesion molecules and proliferation markers and conduct a histomorphometrical study of the follicular wall of letrozole-induced polycystic ovaries.

METHODS

Twenty rats were divided into two groups: a control group (C) of ten rats that received vehicle only (0.9% NaCl solution) once daily p.o. and a treatment group (T) of ten animals administered letrozole at a concentration of 1 mg/kg p.o. dissolved in 0.9% NaCl solution once daily during 21 days. Twenty four h after the last administration, all animals were sacrificed. Control animals were sacrificed in proestrous (n = 5) and diestrous (n = 5). Serum hormone levels, histomorphometrical changes and immunoexpression of intermediate filaments (vimentin, cytokeratins and desmin), cadherins and proliferation cellular nuclear antigen were examined.

RESULTS

The granulosa cell layer of cystic follicles had a greater significant immunostaining for vimentin and cytokeratins. Immunohistochemical localization of desmin was restricted to the theca externa. Positive immunoreactivity for cadherins rises gradually and significantly, together with the follicular development, and immunoreactivity was comparatively stronger in follicular cysts. A significantly higher immunostaining for PCNA cells was observed in secondary and tertiary follicles as compared with atretic and cystic follicles. An increase in the LH, FSH and testosterone serum concentrations was observed in letrozole-treated rats. Estradiol and progesterone showed a considerable reduction.

CONCLUSIONS

The changes observed are probably due to structural and functional alterations that occur during the process of cystogenesis and may be associated with important modifications in the expression of cytoskeletal proteins, cellular adhesion molecules and proliferation markers that may be essential for proper cellular functioning.

Confocal laser scanning microscopy of whole mouse ovaries: excellent morphology, apoptosis detection, and spectroscopy

BACKGROUND

Ovaries consist of numerous follicles, oocytes, and granulosa cells in different stages of development. Many of these follicles will undergo an apoptotic process during the lifetime of the animal. By using proper tissue preparation methods, the events within the whole ovary can be observed by using 3D confocal microscopy.

METHODS

Whole ovaries were stained with LysoTracker Red (LT), fixed with 4% paraformaldehyde (PF) and 1% glutaraldehyde (Glut), dehydrated with methanol (MEOH), and cleared with benzyl alcohol and benzyl benzoate (BABB). Using this tissue preparation technique, the ovary becomes relatively transparent, allowing its morphology to be observed with confocal microscopes. A spectral imaging system (PARISS) located on a conventional microscope was used to interpret the LT dye spectra and fixation products in the tissues with different excitation wavelengths.

RESULTS

Apoptosis in the follicle was detected as clusters of intensely stained granulosa cells located in close proximity to the oocytes. The fixation with Glut and PF preserved morphological details, increased tissue fluorescence, thus increased the signal to noise of the background image.

CONCLUSIONS

Thick tissues can be imaged after they are properly stained, aldehyde fixed, and BABB cleared. LT intensely stained single cells or clusters of apoptotic cells in the follicles and the nucleolus. Spectral differences between LT as an indicator of apoptosis and Glut-PF fixation was used to visualize ovarian morphology and apoptosis. The PARISS spectrophotometer revealed spectral peaks for LT at 609.6 nm and for Glut-PF at 471.3 nm. The proper use of the spectra from these fluorescence molecules is the foundation for high quality morphological images of apoptosis. By sequentially imaging the two probes with a 488 nm laser and a 543/568 nm laser, there was a reduction in fluorescent cross talk and an increase in image quality.

Characterization and expression of different pituitary adenylate cyclase-activating polypeptide/vasoactive intestinal polypeptide receptors in rat ovarian follicles

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a bioactive peptide transiently expressed in preovulatory follicles. PACAP acts by interacting with three types of PACAP receptors. PACAP type I receptor (PAC(1)-R), which binds specifically to both PACAPs and vasoactive intestinal polypeptide (VIP), although with lower affinity, and two VIP receptors, VPAC(1)-R and VPAC(2)-R, which bind to PACAP and VIP with equal affinity. In the present study, we showed the expression of all three receptors in whole ovaries obtained from juvenile and gonadotropin-treated immature rats. A more detailed analysis on cells from preovulatory follicles showed that PAC(1)-R and VPAC(2)-R were expressed in granulosa cells, whereas only VIP receptors were expressed in theca/interstitial (TI) cells and fully grown oocytes presented only PAC(1)-R. The distribution of the VIP receptors was confirmed by immunofluorescence. HCG treatment induced stimulation of PAC(1)-R in granulosa cells and VPAC(2)-R in TI cells. The presence of functional PACAP/VIP receptors was also supported by metabolic studies. We further evaluated the presence of PACAP and VIP receptors by testing the effect of these peptides on apoptosis in granulosa cells cultured, isolated or in whole follicles. Treatment of follicles with PACAP and VIP dose-dependently inhibited apoptosis, while only PACAP significantly inhibited isolated granulosa cells. These results demonstrate a different expression of PACAP/VIP receptors in the various follicle compartments and suggest a possible role for PACAP and VIP on granulosa and TI cells, both during follicle development and ovulation.

Mechanisms of programmed cell death during oogenesis in Drosophila virilis

We describe the features of programmed cell death occurring in the egg chambers of Drosophila virilis during mid-oogenesis and late oogenesis. During mid-oogenesis, the spontaneously degenerating egg chambers exhibit typical characteristics of apoptotic cell death. As revealed by propidium iodide, rhodamine-conjugated phalloidin staining, and the TUNEL assay, respectively, the nurse cells contain condensed chromatin, altered actin cytoskeleton, and fragmented DNA. In vitro caspase activity assays and immunostaining procedures demonstrate that the atretic egg chambers possess high levels of caspase activity. Features of autophagic cell death are also observed during D. virilis mid-oogenesis, as shown by monodansylcadaverine staining, together with an ultrastructural examination by transmission electron microscopy. During the late stages of oogenesis in D. virilis, once again, the two mechanisms, viz., nurse cell cluster apoptosis and autophagy, operate together, manifesting features of cell death similar to those detailed above. Moreover, an altered form of cytochrome c seems to be released from the mitochondria in the nurse cells proximal to the oocyte. We propose that apoptosis and autophagy function synergistically during oogenesis in D. virilis in order to achieve a more efficient elimination of the degenerated nurse cells and abnormal egg chambers.

Serum anti-Müllerian hormone expression in women with premature ovarian failure

BACKGROUND

Premature ovarian failure (POF) is generally irreversible. However, developing follicles up to the antral stage are reported in POF and anti-Müllerian hormone (AMH) might be a good indicator of follicular presence. This study analysed serum AMH, ovarian histology and AMH immunoexpression in POF patients.

METHODS

A cross-sectional study of 48 POF patients in an Endocrinology Department setting. Patients had an ovarian biopsy simultaneously with serum AMH sampling and/or ovarian AMH immunostaining.

RESULTS

Mean serum AMH was 1.04 +/- 1.66 ng/ml. Serum AMH was significantly higher in women with 15 or more follicles at ovarian histology (P = 0.001). Comparison of ovarian AMH immunostaining from POF patients and 10 normal controls revealed a normal AMH expression in POF pre-antral follicles, but a decreased expression at the early antral stages. Serum AMH was undetectable in 77% of the patients with 0-5 AMH immunopositive follicles and detectable in 100% of the patients with more than 15 AMH immunopositive follicles.

CONCLUSIONS

AMH levels in POF patients could identify women with persistent follicles. The decrease of AMH immunoexpression in POF antral follicles could suggest a defect of antral development.

Human chorionic gonadotropin-dependent up-regulation of genes responsible for estrogen sulfoconjugation and export in granulosa cells of luteinizing preovulatory follicles

Estrogen sulfotransferase (EST) is responsible for the sulfoconjugation of estrogens, thereby changing their physical properties and preventing their action via the estrogen receptors. These sulfoconjugated steroids no longer diffuse freely across the lipid bilayer; instead, they are exported by members of the ATP-binding cassette family, such as ABCC1. The objective of this study was to investigate the regulation of EST and ABCC1 during human chorionic gonadotropin (hCG)-induced ovulation/luteinization. The transcripts for EST and ABCC1 were cloned by RT-PCR, and the regulation of their mRNAs was studied in preovulatory follicles obtained during estrus at 0, 12, 24, 30, 33, 36, and 39 h after hCG. Results obtained from RT-PCR/Southern blot analyses showed significant changes in steady-state levels of both EST and ABCC1 mRNA after hCG treatment (P < 0.05). In granulosa cells, a significant increase in EST transcript was observed 30-39 h after hCG. Similarly, ABCC1 transcript levels were induced in granulosa cells 12-39 h after hCG. In contrast, no significant changes in either EST or ABCC1 were detected in theca interna samples after hCG. The increase in EST and ABCC1 transcripts observed in granulosa cells was reflected in preparations of intact follicle walls, suggesting that the granulosa cell layer contributes the majority of EST and ABCC1 expression in preovulatory follicles. The present study demonstrates that follicular luteinization is accompanied not only by a decrease in 17 beta-estradiol biosynthesis but also by an increase in expression of genes responsible for estrogen inactivation and elimination from granulosa cells, such as EST and ABCC1, respectively.

Naturally suppressed apoptosis prevents follicular atresia and oocyte reserve decline in the adult ovary of Lagostomus maximus (Rodentia, Caviomorpha)

It has been widely accepted that mammalian females are born with a non-renewing, finite pool of oocytes that will be continuously cleared by atresia, with only a small proportion of them reaching ovulation. Apoptosis regulates this mass germ cell death, especially through the balance between pro- and anti-apoptotic proteins encoded by the BCL-2 gene family. The caviomorph rodent Lagostomus maximus, the South American plains viscacha, displays the highest ovulation rate known for a mammal releasing 400–800 eggs per cycle. We tested the hypothesis that in L. maximus massive polyovulation is a consequence of reduced apoptosis resulting in suppressed follicular atresia. We found that anti-apoptotic BCL-2 gene is markedly expressed in all kind of follicles from primordial to fully mature antral stages in the adult ovary of L. maximus. On the other hand, pro-apoptotic BAX gene showed weak signals or was undetectable by immunohistochemical examination. Western blot against both proteins confirmed immunohistochemical results. Screening for DNA fragmentation by TUNEL assay was conspicuously negative in ovaries from both pregnant and non-pregnant females. In addition, α-oestrogen receptor also showed an enhanced expression from primordial stage to fully mature antral follicles. Our results show that natural preferential expression of BCL-2 and restricted BAX expression greatly suppresses apoptosis in the ovary of L. maximus. This prevents the decline of the oocyte reserve by abolishing follicular atresia and enables the highest ovulation rate known for a mammal, 400–800 or more eggs per cycle.

Molecular Evidence That Growth of Dominant Follicles Involves a Reduction in Follicle-Stimulating Hormone Dependence and an Increase in Luteinizing Hormone Dependence in Cattle1

The bovine dominant follicle (DF) model was used to identify molecular mechanisms potentially involved in initial growth of DF during the low FSH milieu of ovarian follicular waves. Follicular fluid and RNA from granulosa and theca cells were harvested from 10 individual DF obtained between 2 and 5.5 days after emergence of the first follicular wave of the estrous cycle. Follicular fluid was subjected to RIA to determine estradiol (E) and progesterone (P) concentrations and RNA to cDNA microarray analysis and (or) quantitative real-time PCR. Results showed that DF growth was associated with a decrease in intrafollicular E:P ratio and in mRNA for the FSH receptor, estrogen receptor 2 (ER beta), inhibin alpha, activin A receptor type I, and a proliferation (cyclin D2) and two proapoptotic factors (apoptosis regulatory protein Siva, Fas [TNFRSF6]-associated via death domain) in granulosa cells. In contrast, mRNAs for the LH receptor in granulosa cells and for two antiapoptotic factors (TGFB1-induced antiapoptotic factor 1, LAG1 longevity assurance homolog 4 [Saccharomyces cerevisiae]) and one proapoptotic factor (tumor necrosis factor [ligand] superfamily, member 8) were increased in theca cells. We conclude that the bovine DF provides a unique model to identify novel genes potentially involved in survival and apoptosis of follicular cells and, importantly, to determine the FSH-, estradiol-, and LH-target genes regulating its growth and function. Results provide new molecular evidence for the hypothesis that DF experience a reduction in FSH dependence but acquire increased LH dependence as they grow during the low FSH milieu of follicular waves.

Tyrosine kinase B receptor and its activated neurotrophins in ovaries from human fetuses and adults

The signals initiating the growth of primordial follicles are unknown. Growth factors such as neurotrophin 4/5 (NT-4/5) and brain-derived neurotrophic factor (BDNF) may play a role in this process. To investigate the expression of NT-4/5 and BDNF and their receptor tyrosine kinase B (TrkB) in the early developing follicles, we fixed and froze 12 ovarian samples from adolescents/adults and 31 ovaries from human fetuses. The fixed samples were prepared for immunohistochemical staining for NT-4/5, BDNF and the TrkB receptor. Total RNA was extracted from the frozen ovarian samples, and the expression of NT-4/5, BDNF and the TrkB receptor (full length and two truncated isoforms) was investigated by RT-PCR. Products were resolved by 1% agarose gel electrophoresis and image analysis. Immunohistochemical staining revealed the expression of NT-4/5 and BDNF mainly in oocytes and, in a minority of samples, also in the granulosa cells (GCs); TrkB receptor was identified in oocytes and GCs. Transcripts of NT-4/5, BDNF and all forms of TrkB receptor were identified in the samples. To elucidate whether indeed NT-4/5 and BDNF are involved in growth initiation of human primordial follicles, they should be added to the culture medium.

Immunocytochemical evidence for the presence and location of the neurotrophin-Trk receptor family in adult human preovulatory ovarian follicles

OBJECTIVE

This study was undertaken to evaluate the presence or absence of neurotrophins and their respective receptors within adult human preovulatory follicles.

STUDY DESIGN

Prospective study of neurotrophins and their receptors in follicular cells and unfertilized oocytes from women undergoing aspiration for in vitro fertilization/intracytoplasmic sperm injection. Cells (mural and cumulus granulosa cells, unfertilized oocytes) were examined for immunocytochemical staining of neurotrophin and receptor proteins.

RESULTS

Mural and cumulus granulosa cells were positive for BDNF, NT-4/5, NT-3, and NGF, as well as for Trk B, Trk C, and Trk A receptors. Unfertilized oocytes were positive for Trk B, Trk C, and Trk A receptors.

CONCLUSION

Neurotrophins and their respective receptor proteins are present within the mural and cumulus granulosa cells of adult human preovulatory follicles. Neurotrophin receptors are present in human unfertilized oocytes. The location of the neurotrophins and their receptors suggest both an autocrine and paracrine function within the adult human ovarian follicle.

Role of nitric oxide in ovarian follicular development and egg production in Japanese quail (Coturnix coturnix japonica)

Role of nitric oxide (NO) in regulating the reproductive functions at hypothalamo-hypophysealovarian axis in Japanese quail was studied. In first experiment, metabolites of NO, i.e. nitrite and nitrate (NO2 and NO3) were estimated together in hypothalamus, serum and ovarian follicles of good and poor layers. In the second experiment, different NO modulators such as L-arginine (L-Arg), sodium nitroprusside (SNP) and N(G)-nitro-L-arginine methyl ester, HCl (L-NAME) were administered to the birds. In the first experiment, significantly higher (P < 0.01) NO2 and NO3 levels in serum, hypothalamus and largest (F1) ovarian follicles were observed in good layers as compared to poor layers. Higher (P < 0.05) NO2 and NO3 concentration was observed in F1 follicles than smaller follicles (F2) only in good layers. The NO2 and NO3 concentration was significantly reduced (P < 0.05) in post ovulatory follicles (POFs) in comparison to F1 and F2 follicles. In the second experiment, the serum NO2 and NO3 concentrations were higher (P < 0.05) in the SNP, lower (P < 0.05) in the L-Name group and unchanged in the L-Arg treated group in comparison to control group. compared to control, L-Arg and SNP increased (P < 0.05) the hypothalamic NO2 and NO3 concentration where as L-NAME reduced (P < 0.05) these levels. The NO2 and NO3 concentration was increased (P < 0.05) as the follicle size increased and it was significantly reduced (P < 0.05) in POFs. The higher (P < 0.05) follicular NO2 and NO3 concentration was observed in L-Arg group in comparison to control group. Egg production was also found to be higher (P < 0.05) in L-Arg group whereas it was not different (P > 0.05) in SNP and L-NAME treated groups. The yolk weight and yolk to albumin ratio was reduced (P < 0.05) in L-NAME group in comparison to control group. It may be concluded from the present study that NO plays a key role in regulating follicular development, ovulatory mechanisms and egg production in Japanese quail.

In vitro effect of vitellogenin on steroid production by ovarian follicles of greenback flounder Rhombosolea tapirina

Ovarian follicles from vitellogenic greenback flounder (Rhombosolea tapirina) were incubated in L15 medium alone, or containing human chorionic gonadotropin (hCG), dibutyryl cyclic AMP (dbcAMP) or the steroid precursors testosterone (T), 17-hydroxyprogesterone (17P) and androstenedione (A) in the presence of vitellogenin (Vtg) at 0.1-5.0mg mL(-)(1). Medium concentrations of 17beta-estradiol (E(2)) and T were measured by radioimmunoassay. HCG generally stimulated follicular E(2) but not T production, whereas 17P, A and T stimulated production of E(2), T, and E(2) respectively. Treatment of follicles with dbcAMP inhibited follicular E(2) production, but increased follicular T production at high doses. The effect of low concentrations of Vtg on follicular steroid production was variable; however, higher doses of Vtg significantly suppressed basal, hCG-, dbcAMP- and steroid precursor-stimulated follicular E(2) and T production. The results of this study show that high concentrations of Vtg may suppress follicular steroid production by interfering in the steroidogenic pathway. This suggests that Vtg may regulate its own production by limiting the ovarian production of E(2).

Expression of phospholipase A2 group IVA (PLA2G4A) is upregulated by human chorionic gonadotropin in bovine granulosa cells of ovulatory follicles

Prostaglandins are required for the ovulatory process, and their biosynthesis depends on the initial release of arachidonic acid from membrane phospholipids. We hypothesized that phospholipase A2 group IVA (PLA2G4A) expression is upregulated in granulosa cells (GC) at ovulation. We have characterized bovine PLA2G4A cDNA, and investigated its spatiotemporal regulation at the mRNA and protein levels in hCG-induced ovulatory follicles and in vitro, using forskolin-stimulated GC. Regulation of PLA2G4A mRNA expression was studied in GC obtained from bovine follicles collected at different developmental stages: small follicles (2-4 mm), dominant follicles at Day 5 (D5) of the estrous cycle, ovulatory follicles 24 h following injection of hCG, and corpus luteum at D5. PLA2G4A mRNA increased by 14-fold in GC of hCG-stimulated versus dominant follicles (P < 0.0001). Follicular walls obtained from ovulatory follicles recovered at 0, 6, 12, 18, and 24 h post-hCG injection showed an initial 16-fold increase in PLA2G4A transcript at 12 h that reached a 45-fold increase at 24 h, as compared to 0 h (P < 0.0001). Immunoblots of GC extracts showed an initial induction of the PLA2G4A protein at 18 h post-hCG, reaching a maximum at 24 h. Immunohistochemistry observations showed that PLA2G4A signal was mainly observed in mural GC compared to antral GC in hCG-stimulated follicles. Stimulation of cultured bovine GC with 10 microM of forskolin caused an increase in PLA2G4A mRNA and protein. Ovulation is associated with an LH/hCG-dependent induction of PLA2G4A in GC via the adenylyl cyclase/cAMP pathway.

Transient expression of SOX9 protein during follicular development in the adult mouse ovary

SOX9 is an essential activating transcription factor that plays a critical role in Sertoli cell differentiation and subsequent testis cord formation. Cytoplasmic SOX9 is present in both sexes during early gonadal embryogenesis. While in males the protein is later translocated into the nucleus of pre-Sertoli cells, its expression is rapidly turned off in females. In mammalian male gonads, SOX9 activates the expression of anti-Müllerian hormone (AMH), a male hormone that initiates Müllerian ducts regression and that is also expressed in postnatal ovarian follicles. Here, we confirm that the SOX9 protein is not present in the immature ovary but also show that SOX9 is transiently expressed in the mature ovary depending on the follicular cycle. Indeed, SOX9 protein was found in the nuclear compartment of the inner cells of the theca interna cell layer which surrounds the pre-antral/antral follicles. In contrast, no expression was detected in the AMH expressing granulosa cells. While these findings exclude the possibility that SOX9 regulates AMH expression in the ovary, they show that SOX9 could nevertheless play a role in the developing follicle.

Identification of a novel C2 domain factor in ovaries of orange-spotted grouper (Epinephelus coioides)

Follicle consists of an oocyte and a lot of surrounding follicular cells, and significant interactions exist between the oocyte and the somatic cells. In this study, a novel cDNA has been screened from a subtractive cDNA library between tail bud embryos and blastula embryos in the protogynous hermaphrodite orange-spotted grouper (Epinephelus coioides). Its full-length cDNA is 821 bp, and has an ORF of 414 bp for encoding a peptide of 137 aa, which shows 38%, 37%, 33%, and 33% homology with 4 putative proteins screened from zebrafish (Danio rerio). Conserved domain search in NCBI reveals a single C2 domain existing in the C2 domain superfamily proteins, and has only 7 beta strands in comparison with 8 beta strands of C2 domains in other C2 domain superfamily proteins. Artificial sex reversal, RT-PCR analysis and Western blot detection demonstrated ovary-specific expression of the C2 domain factor, and therefore the novel gene was designated as E. coioides ovary-specific C2 domain factor, EcOC2 factor. Moreover, predominant expression of EcOC2 factor was further revealed in grouper mature ovary, and its strong immunofluorescence signals were located between granulosa cells and oocyte zona radiata in grouper mature follicles. The data indicate that the novel EcOC2 factor might be a main component that associates between granulosa cells and the oocyte during oocyte maturation, and might play significant roles in regulating oocyte maturation and ovulation. Further studies on its developmental behaviour and physiological functions will elucidate the interactions between oocyte and the surrounding somatic cells and the underlying molecular mechanisms.

Expression pattern of glycoconjugates in the Bidderian and ovarian follicles of the Brazilian toad Bufo ictericus analyzed by lectin histochemistry

The Bidder's organ and ovary of the Brazilian toad Bufo ictericus were studied by light microscopy, using hematoxylin-eosin (HE) and periodic acid Schiff (PAS) staining. The expression and distribution of carbohydrate moieties was analyzed by lectin histochemistry, using 8 lectins with different carbohydrate specificities: Ulex europaeus (UEA I), Lens culinaris (LCA), Erythrina cristagalli (ECA), Arachis hypogaea (PNA), Ricinus communis (RCA I), Aleuria aurantia (AAA), Triticum vulgaris (WGA), and Glycine maximum (SBA). The results showed that the Bidderian zona pellucida presented alpha-mannose, alpha-L-fucose, beta-D-galactose, N-acetyl-D-glucosamine, and alpha/beta-N-acetyl-galactosamine residues. The Bidderian follicular cells showed the presence of beta-D-galactose and N-acetyl-D-glucosamine. In the extracellular matrix, alpha-mannose and alpha/beta-N-acetyl-galactosamine residues were detected. The ovarian zona pellucida showed alpha-L-fucose, N-acetyl-D-glucosamine, alpha/beta-N-acetyl-galactosamine residues, and alpha-mannose and N-acetyl-D-glucosamine residues were detected in the follicular cells. Thus, the zona pellucida in both organs contains N-acetyl-D-glucosamine, and alpha/beta-N-acetyl-galactosamine residues. alpha-L-fucose residues were detected in the zona pellucida of both organs, using different lectins. Considering that beta-D-galactose residue was absent from ovary but present in the Bidder's organ, this sugar residue may play an important role in follicle development, blocking the Bidderian follicles and preventing further development of the Bidder's organ into a functional ovary.

[The nucleolus in oocytes of multylayer mouse follicles: topography of fibrillarin, RNA polymerase I and coilin]

By electron microscopy, conventional fluorescence and confocal microscopy, some features of structural and molecular organization of the nucleolus in oocyte nucleus from mouse multilayer follicles were examined. The examined nucleolus lacks almost all characteristic nucleolar components, such as fibrillar centers, dense fibrillar and granular components. This nucleolus consists exclusively of a homogenous filamentous material and is penetrated by numerous interstices. Besides, a striking association of the nucleolus with coilin, a marker of Cajal bodies, was observed. We could map the coilin accumulation in three different areas: around, in the periphery, or inside the nucleolus. Additionally, we examined a topological relationship between coilin and two key proteins of nucleolar transcription-processing machinery, RNA polymerase I and fibrillarin. RNA polymerase I rather than fibrillarin was found to be colocalized with coilin. Finally, we propose that data on dynamics of coilin relation with the nucleolus may elucidate a possible role of coilin in functional relationship between the nucleolus and Cajal bodies.

Ultrastructural localisation of calcium deposits in pig ovarian follicles

Calcium intracellular signaling regulates many intracellular events including oocyte maturation. This signaling is strongly dependent on the influx of calcium ions from extracellular spaces and on the state of intracellular calcium stores. In this study, intracellular calcium deposits were detected in follicle-enclosed pig oocytes using the combined oxalate-pyroantimonate method. These deposits were observed in the nucleus, the mitochondria, the cytoplasm, and on the surface of lipid droplets. The amount of calcium deposits was expressed as a percentage of the area of the respective cellular compartment, which is covered with calcium deposits on ultrathin sections. The distribution of calcium deposits in oocytes changed during folliculogenesis. The amount of calcium deposits in nuclei (1.11% of the area of oocyte nuclei) and cytoplasm (1.02%) in oocytes from secondary and early antral follicles (0.90% nuclei; 0.99% cytoplasm) is significantly lower (P < 0.05) than the amount of calcium deposits in these compartments in oocytes from primary follicles (2.51% nuclei; 2.34% cytoplasm) or antral follicles with growing oocyte (2.91% nuclei; 2.21% cytoplasm). The amount of calcium deposits in mitochondria of oocytes from primary follicles (1.27%) or antral follicles with growing oocyte (1.14%) is significantly lower (P < 0.05) than in the nucleus (2.51% in oocytes from primary follicles; 2.91% in growing oocytes from antral follicles) or cytoplasm (2.34% in oocytes from primary follicles; 2.21% in growing oocytes from antral follicles). The amount of calcium deposits in the cytoplasm of fully-grown oocytes (1.46%) dropped to levels significantly lower (P < 0.05) than those observed in the oocyte nucleus (2.29%). On the basis of these data, we can conclude that the population of follicles on pig ovaries differs in the distribution and concentration of calcium deposits in oocytes, and these changes may be involved in the regulation of the meiotic competence of oocytes.

Lead concentrates in ovarian follicle compromises pregnancy

Following absorption, lead can concentrate in bodily compartments where it disrupts cellular processes and can result in detrimental health consequences. The concentration and impact of lead within follicular fluid has not been characterized and we used inductively coupled plasma mass spectroscopy (ICP-MS) to determine lead levels in blood and follicular fluid from nine patients undergoing in vitro fertilization (IVF) treatment. Lead levels within follicular fluid were found to be significantly higher in non-pregnant patients compared to pregnant patients suggesting that elevated concentrations of the environmental toxicant lead adversely affect female reproduction.

Cx37 and Cx43 localize to zona pellucida in mouse ovarian follicles

In the ovarian follicle, granulosa cells adjacent to the oocyte extend processes through the zona pellucida matrix, and these projections establish gap junctions both with the oocyte and with neighboring transzonal projections. The identity of connexins contributing to gap junctions between transzonal projections has not been extensively studied. Here, we examined the expression pattern of Cx37 and Cx43 in mouse zona pellucida using multiple connexin-specific antibodies. Immunofluorescence staining revealed abundant Cx37 and Cx43 puncta within the zona pellucida of both preantral and antral follicles. Cx37 persisted in the zona pellucida of mature follicles up to 5 h after an ovulatory stimulus whereas Cx43 was reduced in the zona pellucida by 3 h after an ovulatory stimulus. We suggest that in addition to its role in oocyte-granulosa cell communication, Cx37 could enable a distinct communication pathway between those granulosa cells that are in direct contact with the oocyte.

Oestrogen receptor α and β, androgen receptor and progesterone receptor mRNA and protein localisation within the developing ovary and in small growing follicles of sheep

A first step to elucidating the roles that steroids may play in the processes of ovarian development and early follicular growth is to identify the cell types that are likely to be receptive to steroids. Thus, cell types expressing receptors for oestrogen (α and β form; ERα and ERβ respectively), androgen (AR) and progesterone (PR) were determined by in situ hybridisation and immunohistochemistry in ovine ovarian tissues collected during ovarian development and follicular formation (days 26–75 of fetal life) as well as during the early stages of follicular growth. Expression of ERβ was observed early during ovarian development and continued to be expressed throughout follicular formation and also during the early stages of follicular growth. ERβ was identified in germ cells as well as in the granulosa cells. At the large preantral stage of follicular growth, expression of ERα was also consistently observed in granulosa cells. AR was first consistently observed at day 55 of fetal life in stroma cells throughout the ovary. Within the follicle, expression was observed in granulosa and thecal cells from the type-2 to -3 stage of follicular growth. PR mRNA did not appear to be expressed during ovarian development (days 26–75 of gestation). However, PR (mRNA and protein) was observed in the theca of type-3 (small preantral) and larger follicles, with mRNA – but not protein – observed in granulosa cells of some type-4 and 5 follicles. Expression of ERβ, ERα and AR, as well as PR, was also observed in the surface epithelium and ovarian stroma of the fetal, neonatal and adult ovary. Thus, in sheep, steroid hormones have the potential to regulate the function of a number of different ovarian cell types during development, follicular formation and early follicular growth.

Remodeling of extracellular matrix at ovulation of the bovine ovarian follicle

Using immunohistochemistry and RNA analyses we examined the fate of components of a newly identified matrix that develops between granulosa cells (focimatrix, abbreviated from focal intraepithelial matrix) and of the follicular basal lamina in ovulating bovine ovarian follicles. Pre- and postovulatory follicles were generated by treatment with estradiol (Day 1), progesterone (Days 1-10), and prostaglandin analogue (Day 9) with either no further treatment (Group 1, n = 6) and or with 25 mg porcine LH (Day 11, Group 2, n = 8 or Day 10, Group 3, n = 8) and ovariectomy on Day 12 (12-14 hr post LH in Group 2, 38-40.5 hr in Group 3). In the time frame examined no loss of follicular basal lamina laminin chains beta2 and gamma1 or nidogen 1 was observed. In the follicular basal lamina collagen type IV alpha1 and perlecan were present prior to ovulation; after ovulation collagen type IV alpha1 was discontinuously distributed and perlecan was absent. Versican in the theca interna adjacent to the follicular basal lamina in preovulatory follicles was not observed post ovulation, however, the granulosa cells then showed strong cytoplasmic staining for versican. Expression of versican isoforms V0, V1, and V3 was detected at all stages. Focimatrix was observed in preovulatory follicles. It contained collagen type IV alpha1, laminins beta2 and gamma1, nidogen 1 and perlecan and underwent changes in composition similar to that of the follicular basal lamina. In conclusion focimatrix and the follicular basal lamina are degraded at ovulation. Individual components are lost at different times.

Gene expression of glucose transporter (GLUT) 1, 3 and 4 in bovine follicle and corpus luteum

Glucose is the main energy substrate in the bovine ovary, and a sufficient supply of it is necessary to sustain the ovarian activity. Glucose cannot permeate the plasma membrane, and its uptake is mediated by a number of glucose transporters (GLUT). In the present study, we investigated the gene expression of GLUT1, 3 and 4 in the bovine follicle and corpus luteum (CL). Ovaries were obtained from Holstein x Japanese Black F1 heifers. Granulosa cells and theca interna layers were harvested from follicles classified into five categories by their physiologic status: follicular size (>or= 8.5 mm: dominant; < 8.5 mm: subordinate), ratio of estradiol (E(2)) to progesterone in follicular fluid (>or= 1: E(2) active;<1: E(2) inactive), and stage of estrous cycle (luteal phase, follicular phase). CL were also classified by the stage of estrous cycle. Expression levels of GLUT1, 3 and 4 mRNA were quantified by a real-time PCR. The mRNA for GLUT1 and 3 were detected in the bovine follicle and CL at comparable levels to those in classic GLUT-expressing organs such as brain and heart. Much lower but appreciable levels of GLUT4 were also detected in these tissues. The gene expression of these GLUT showed tissue- and stage-specific patterns. Despite considerable differences in physiologic conditions, similar levels of GLUT1, 3 and 4 mRNA were expressed in subordinate follicles as well as dominant E(2)-active follicles in both luteal and follicular phases, whereas a notable increase in the gene expression of these GLUT was observed in dominant E(2)-inactive follicles undergoing the atretic process. In these follicles, highly significant negative correlations were observed between the concentrations of glucose in follicular fluid and the levels of GLUT1 and 3 mRNA in granulosa cells, implying that the local glucose environment affects glucose uptake of follicles. These results indicate that GLUT1 and 3 act as major transporters of glucose while GLUT4 may play a supporting role in the bovine follicle and CL.

Expression of fibroblast growth factor-8 and regulation of cognate receptors, fibroblast growth factor receptor-3c and -4, in bovine antral follicles

Paracrine cell signaling is believed to be important for ovarian follicle development, and a role for some members of the fibroblast growth factor (FGF) family has been suggested. In the present study, we tested the hypothesis that FGF-8 and its cognate receptors (FGFR3c and FGFR4) are expressed in bovine antral follicles. RT-PCR was used to analyze bovine Fgf8, Fgfr3c and Fgfr4 mRNA levels in oocytes, and granulosa and theca cells. Fgf8 expression was detected in oocytes and in granulosa and theca cells; this expression pattern differs from that reported in rodents. Granulosa and theca cells, but not oocytes, expressed Fgfr3c, and expression in granulosa cells increased significantly with follicle estradiol content, a major indicator of follicle health. Fgfr4 expression was restricted to theca cells in the follicle, and decreased significantly with increasing follicle size. To investigate the potential regulation of Fgfr3c expression in the bovine granulosa, cells were cultured in serum-free medium with FSH or IGF-I; gene expression was upregulated by FSH but not by IGF-I. The FSH-responsive and developmentally regulated patterns of Fgfr3c mRNA expression suggest that this receptor is a potential mediator of paracrine signaling to granulosa cells during antral follicle growth in cattle.

Distribution of androgen receptor in rat ovarian follicles undergoing atresia at the beginning of pregnancy

The immunohistochemical localisation of androgen receptor (AR) was investigated in a cohort of ovarian antral follicles developing, and subsequently undergoing atresia, in a hyperprolactinaemic milieu at the beginning of pregnancy in rats. Differentiation of the investigated follicles, observed during the first 5 days of pregnancy, was accompanied by a centripetal disappearance of androgen nuclear receptor in the granulosa layer, which did not include the cumulus oophorus complex and some antral granulosa cells. This pattern of decline resembled that typical of follicles maturing during the oestrous cycle but took longer to occur. The follicles did not ovulate and subsequently underwent atresia. The degeneration of some follicles was accompanied by a further loss of AR in the cumulus granulosa cells, but a strong positive AR immunoreaction persisted in the oocyte nucleoli. Some perinatal and early antral atretic follicles were found. In most cases their granulosa layers were AR-positive, although often only weakly. However, follicles with AR negative granulosa layers were also encountered. Nuclear immunolabelling for AR was positive in luteinized follicles. It can be concluded that follicular atresia involves changes in AR distribution which can be demonstrated as an abnormal depletion or persistence of AR.

Estrogen Mediates Phosphorylation of Histone H3 in Ovarian Follicle and Mammary Epithelial Tumor Cells via the Mitotic Kinase, Aurora B

Cells of the ovarian follicle undergo extensive proliferation and differentiation from the time that the follicle escapes from the primordial state to its acquisition of ovulatory capacity. We examined the dynamic modification of the phosphorylation state of the histone H3 N-terminal tail in granulosa cells during follicular development. In rodent follicles, the granulosa cell H3 phosphorylation on Ser10 peaks during proestrus. This epigenetic mark is induced by both FSH and 17β-estradiol (E2), acting independently. E2-induced H3 phosphorylation fails to occur in mice with inactivated α-isoform of the nuclear estrogen receptor. E2 induction of histone phosphorylation is attenuated by cell cycle inhibition. Further, E2 induces the activity of the mitotic kinase, Aurora B, in a mammary tumor cell model where mitosis is estrogen receptor-α dependent. These results provide evidence for mitotic regulation in follicle development by estrogen and demonstrate a previously undiscovered mechanism for induction of cell proliferation in ovarian and mammary gland cells.

Changes in steroidogenic enzyme and steroidogenic acute regulatory protein messenger RNAs in ovarian follicles during ovarian development of rainbow trout (Oncorhynchus mykiss)

In salmonid fishes, estradiol-17beta (E2) and 17alpha,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P) are the major steroid hormones controlling oocyte growth (vitellogenesis) and final maturation (resumption of meiosis). The aim of this study was to determine changes in mRNAs encoding ovarian steroidogenic enzymes and steroidogenic acute regulatory protein (StAR) during ovarian development in female rainbow trout. We analyzed the levels of mRNAs encoding the enzymes P450 side-chain cleavage enzyme (P450scc), 3beta-hydroxysteroid dehydrogenase (3beta-HSD), 17alpha-hydroxylase/C17-C20 lyase (P450c17), aromatase (P450arom), and carbonyl reductase-like 20beta-hydroxysteroid dehydrogenase (20beta-HSD), and StAR in developing ovarian follicles of rainbow trout by Northern blot, in relation to the pattern of serum E2 and 17,20beta-P levels. Serum E2 levels were elevated during vitellogenesis and decreased prior to an ovulatory increase in 17,20beta-P. Transcripts for P450scc and P450c17 increased in late vitellogenic follicles, then decreased in post-ovulatory follicles. In contrast, P450arom transcripts were abundant during vitellogenesis and then declined as vitellogenesis was completed and were barely detectable in post-ovulatory follicles. 3beta-HSD mRNA levels increased in late vitellogenic follicles and were maintained at high levels in post-ovulatory follicles. 20beta-HSD and StAR mRNA levels were very low during vitellogenesis, and then strongly increased during late vitellogenesis to a peak in post-ovulatory follicles. These results indicate that the expression of genes encoding steroidogenic enzymes and StAR change dynamically, dependent on the developmental stages of rainbow trout follicles. The acquisition of the ability of later stage follicles to rapidly produce large quantities of 17,20beta-P appears to be supported by a preparatory increase in mRNAs encoding StAR and other steroidogenic enzymes.

TrkA and p75NTR in the ovary of adult cow and pig

Neurotrophins play a critical role in the development of the mammalian ovary, oogenesis and folliculogenesis. In this study we investigated the cell localization of the two main receptors for nerve growth factor (NGF), TrkA and p75NTR, in the cow and pig ovary, using immunohistochemistry. Specific immunoreactivity for TrkA and p75NTR was detected in the ovary of both species, but the pattern and intensity of immunostaining were marginally different between them. The follicular cells regularly expressed immunoreactivity for both receptors. Immunoreactivity was also detected in the oocytes, independently of the maturational stage of the follicles, with the exception of primordial and primary follicles of the pig which did not display p75NTR. Taken together, these results suggest a possible direct role of NGF on oocytes expressing TrkA and p75NTR, in addition to the well-known roles in other ovary functions. The practical relevance of these data remains to be clarified.

A novel role for the Bombyx Slbo homologue, BmC/EBP, in insect choriogenesis

One previously unidentified cDNA clone coding for a C/EBP factor, BmC/EBP, was isolated from Bombyx mori follicular cells. This is the first time that a C/EBP factor has been isolated and characterized in Lepidoptera. We provide information concerning structural features and developmental specificity, as well as in vitro interaction properties with chorion gene promoter modules. BmC/EBP was capable of effectively recognizing homologous binding sites from chorion gene promoters derived from flies and other moths, despite significant diversity of chorion structure, gene organization, and gene expression profiles. We propose that the relative concentration of BmC/EBP, in relation to its differential binding affinity for promoter cis-elements, results in activation or repression of silkmoth chorion gene expression.

Alterations in follicular IGFBP mRNA expression and follicular fluid IGFBP concentrations during the first follicle wave in beef heifers

The objective was to determine the pattern of IGFBP-2, -3 and -4 gene expression and follicular fluid concentrations of IGFBP-2, -3, -4 and -5 during emergence, selection and dominance of the first follicle wave of the estrous cycle in cattle and during exogenous steroid treatment. Heifers (n = 35) were ovariectomized at 36 (n = 7), 66 (n = 8), 84 (n = 12) and 108 (n = 8) h after the onset of estrus. Heifers in the 84 h ovariectomy group were sub-divided to receive either no treatment (n = 6) or were treated with a progesterone-releasing intravaginal device (n = 6, PRID) and 0.75 mg estradiol benzoate i.m. at the approximate time of ovulation, 30 h post estrus until ovariectomy. Within heifers the four largest follicles recovered following ovariectomy were ranked on size (F1, F2, F3 and F4). At 36 h IGFBP gene expression and follicular fluid IGFBP concentrations were similar in all follicles (F1-F4). Mean diameter of the F1 follicle increased (P < 0.05) between 36 and 84 h with no difference between 84 and 108 h. The F1 follicle had the highest (P < 0.05) concentration of estradiol compared with the F2, F3 and F4 at 84 and 108 h. There was no granulosa cell IGFBP-2 mRNA in F1 follicles at 84 or 108 h. Intrafolliclar IGFBP-2 concentrations were lower (P < 0.05) in the F1 compared with F3 and F4 follicles at 108 h. There was no difference in theca cell IGFBP-4 mRNA expression at 108h, but amounts of follicular fluid IGFBP-4 were lower (P < 0.05) in F1 follicles compared with F3 and F4 follicles at 108 h. IGFBP-3 mRNA was localized in the theca layer of all follicles examined with no difference in expression or follicular fluid concentrations during emergence, selection and dominance of the first follicle wave. IGFBP-5 concentrations were higher (P < 0.05) in follicular fluid of F3 follicles at 108 h compared with the F3 at 36 h. In conclusion follicular dominance was associated with low or decreased follicular fluid concentrations of IGFBP-4 and -5, increased estradiol and differential regulation of IGFBP production.

Alterations in follicular dynamics and steroidogenic abilities induced by heat stress during follicular recruitment in goats

We investigated the changes in follicular dynamics and steroidogenic activity during heat stress in goats. Adult female goats were exposed to heat stress at 36 degrees C and 70% relative humidity for 48 h and then injected with prostaglandin (PG) F2alpha (the time of PGF2alpha injection was designated as 0 h). In experiment 1, every follicle greater than 2 mm in diameter was monitored by ultrasonography to investigate the follicular dynamics, and plasma concentrations of FSH, LH, progesterone, and oestradiol were measured from -48 h to 120 h. In experiment 2, the follicles were recovered from the goats at 48 h, and the concentration of oestradiol, the aromatase activity, and the LH receptor level in the follicles were determined. In control (non-heat-stressed) goats, ovulatory follicles were mainly recruited from -24 h to 0 h, whereas no follicles recruited during that period were ovulated in the heat-stressed goats. The timing of the recruitment of ovulatory follicles was delayed by heat stress by approximately 24 h. The plasma concentration of oestradiol in the heat-stressed goats was significantly lower from 36 to 54 h compared with the controls, although the concentrations of FSH and progesterone did not differ between the treatments. In addition, the concentration of oestradiol, the aromatase activity, and the LH receptor level in the follicles from heat-stressed goats were significantly lower compared with the controls. These results indicate that heat stress during follicular recruitment suppresses subsequent growth to ovulation, accompanied by decreased LH receptor level and oestradiol synthesis activity in the follicles.

Expression of mRNAs encoding insulin-like growth factor (IGF) ligands, IGF receptors and IGF binding proteins during follicular growth and atresia in the ovine ovary throughout the oestrous cycle

The components of the insulin-like growth factor (IGF) system appear to be involved in the regulation of ovarian follicular growth and atresia in sheep. However, previous studies have only investigated a select few components of the system. The aim of the present study was to investigate the expression of mRNA encoding all of the components of the sheep IGF system among follicles of varying size and health status throughout the oestrous cycle using sheep-specific ribonucleotide probes and in situ hybridisation. For all IGF components, gene expression was unaffected by stage of oestrous cycle. IGF-I mRNA expression in all classes of follicle was generally low throughout the oestrous cycle, while IGFBP-1 mRNA expression could not be demonstrated at all. In contrast, there was relatively intense follicular expression of mRNAs encoding all remaining IGF system components. For IGF-II, both IGF receptors and IGFBP-2, -3, -4, -5, and -6, gene expression decreased as follicles increased in diameter (P < 0.01). IGF-II, type I IGF-R and IGFBP-2, -3, -4, and -6 mRNA expression significantly decreased as follicles progressed from healthy to atretic status (P < 0.01), whereas gene expression for type II IGF-R and IGFBP-5 was greater in atretic follicles (P < 0.01). This study demonstrates the spatial patterns of follicular gene expression for all of the IGF system components in cycling sheep for the first time. These results further highlight the potential functional role of IGF-II, in contrast to IGF-I, in the autocrine and/or paracrine regulation of follicle growth in sheep.

Role of vascular endothelial growth factor in ovarian physiology - an overview

In the female reproductive system, as in a few adult tissues, angiogenesis occurs as a normal process and is essential for normal tissue growth and development. In the ovary, new blood vessel formation facilitates oxygen, nutrients, and hormone substrate delivery, and also secures transfer of different hormones to targeted cells. Ovarian follicle and the corpus luteum (CL) have been shown to produce several angiogenic factors, however, vascular endothelial growth factor (VEGF) is thought to play a paramount role in the regulation of normal and abnormal angiogenesis in the ovary. Expression of VEGF in ovarian follicles depends on follicular size. Inhibition of VEGF expression results in decreased follicle angiogenesis and the lack of the development of mature antral follicles. The permeabilizing activity of VEGF is thought to be involved in follicle antrum formation and in the ovulatory process. In the CL, VEGF expression corresponds to different patterns of angiogenesis during its lifespan. In most the species, higher VEGF expression in the early luteal phase is essential for the development of a high-density capillary network in the CL. However, high VEGF expression may be still maintained in the mid-luteal phase to increase vascular permeability that results in enhancement of luteal function. During gestation, VEGF is thought to be important for the persistence of the CL function for a longer than in the nonfertile cycle period of time. Further elucidation of specific roles of VEGF in ovarian physiology may help to understand the phenomenon of luteal insufficiency and reveal novel strategies of ovarian angiogenesis manipulation to alleviate infertility or to control fertility.

Identification of new proteins in follicular fluid from mature human follicles by direct sample rehydration method of two-dimensional polyacrylamide gel electrophoresis

Human follicular fluid (HFF) includes various biologically active proteins which can affect follicle growth and oocyte fertilization. Thus far, these proteins from mature follicles in human follicular fluid have been poorly characterized. Here, two-dimensional polyacrylamide gel electrophoresis (2-DE) with matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) was used to identify new proteins in HFF. Mature follicular fluids were obtained from five females after oocyte collection during in vitro fertilization (IVF). We directly rehydrated HFF samples, obtained high-resolution 2-DE maps, and processed them for 2-DE and MALDI-MS. One hundred eighty spots were detected and 10 of these spots were identified. By the 2-DE database, six of them had been reported, as proteins already existing in HFF. Hormone sensitive lipase (HSL), Unnamed protein product 1 (UPP1), Unnamed protein product 2 (UPP2), and apolipoprotein A-IV precursor were newly detected. HSL and apolipoprotein A-IV participate in lipid metabolism. UPP1 has a homology with selenocysteine lyase. We found by RT-PCR that these genes are expressed from human primary granulosa cells. The proteins identified here may emerge as potential candidates for specific functions during folliculogenesis, hormone secretion regulation, or oocyte maturation. Further functional analysis of these proteins is necessitated to determine their biological implications.

A newly identified zona pellucida glycoprotein, ZPD, and dimeric ZP1 of chicken egg envelope are involved in sperm activation on sperm-egg interaction

Fertilization begins with interaction between the sperm and the egg. The surface of the vertebrate oocyte is covered with the egg envelope, which is composed of ZP (zona pellucida) glycoproteins. We have identified two glycoproteins, ZP1/gp97 and ZPC/gp42, as the major components of the chicken egg envelope. In the present study, another 42 kDa protein, designated ZPD, has been found as a new major component of the chicken egg envelope. ZPD was specifically released from the egg envelope by ultrasonication treatment without urea. ZPD cDNA was cloned using a chicken granulosa cell cDNA pool. The deduced amino acid sequence showed that preproprotein of ZPD is composed of 418 amino acid residues with four potential N-glycosylation sites and includes a ZP domain, common in vertebrate ZP glycoproteins, and a transmembrane domain. ZPD belongs phylogenetically to a distinct group from known ZP glycoprotein subfamilies, ZPA, ZPB, and ZPC. In two-dimensional gel electrophoresis ZPD proteins were identified to be several isoforms with different pI values between 5 and 7. ZP1, ZPC and the newly identified ZPD were confirmed to be the major components of chicken egg envelope by MS of proteolytic digests of whole egg envelope. The in vitro incubation of chicken sperm with calcium ionophore A23187 induced sperm activation, resulting in the fragmentation and release of a 41 kDa PNA (peanut agglutinin)-positive glycoprotein and the decrease or loss of sperm PNA-stainability. The incubation with ZPD and dimeric ZP1, but not ZPC and monomeric ZP1, also induced the decrease or loss of sperm PNA-stainability, suggesting the in vitro sperm activation by these ZP components. Collectively, ZPD might bind loosely to egg envelope matrix and play a key role in the sperm activation on avian sperm-egg interaction.

Maternal diabetes adversely affects preovulatory oocyte maturation, development, and granulosa cell apoptosis

Maternal diabetes adversely affects preimplantation embryo development and pregnancy outcomes. The objective of this study was to determine whether diabetes has an impact at an earlier stage of development, the preovulatory oocyte. Models of both acute and chronic insulin-dependent diabetes were used. Acute hyperglycemia was induced by a single streptozotocin injection. Akita mice, which harbor an autosomal dominant mutation causing them to be chronically hypoinsulinemic and hyperglycemic, were used. In both models, preovulatory oocytes were markedly smaller when compared with control animals. A significantly greater number of control oocytes had progressed to meiotic maturation before diabetic oocytes. Both models were found to have smaller, less developed ovarian follicles with a greater number of apoptotic foci by histological evaluation as well as by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling staining. Immunohistochemistry displayed a greater amount of TNF-related apoptosis-inducing ligand (TRAIL) and KILLER, a key murine ligand and receptor involved in the extrinsic pathway, expressed in cumulus cells from hyperglycemic mice compared with controls, suggesting that this apoptotic pathway may be up-regulated under diabetic stress. Elevated KILLER expression was also confirmed through Western blotting. Connexin-43 expression was found to be lower by immunohistochemistry and Western blot analysis in the diabetic samples. Both models of maternal hyperglycemia and hypoinsulinemia may have a detrimental effect on oocyte maturation and development as detailed by the smaller sizes of oocytes and developing ovarian follicles, the lowered percentage reaching germinal vesicle breakdown, and the greater amount of apoptosis. In addition, there may be dysfunctional or decreased communication in diabetic oocytes, as demonstrated by lower expression of connexin-43.

Differential expression and localisation of connexin-37 and connexin-43 in follicles of different stages in the 4-week-old mouse ovary

Mammalian female fertility is critically dependent on timely coordinated intercellular communication between follicle cells. Gap junctions are small, membrane-bound, aqueous channels that couple adjacent cells ionically and gap junction proteins, connexin-37 (Cx37) and connexin-43 (Cx43) both participate in sustaining proper growth and maturation of the oocyte. The purpose of the present study was to localise Cx37 and Cx43 in sections of ovarian mouse follicles of different developmental stage, and compare their relative expression using immunofluorescence and confocal microscopy. Cx37 exclusively localised to oocytes of all follicle stages, and the estimated number of Cx37 gap junctions per mum oocyte circumference in follicles of stage 2 to stage 6 increased in parallel to oocyte and follicle growth, reaching a maximum in the pre-antral stage. Acetylated alpha-tubulin and Cx37 double labelling revealed that the majority of Cx37 gap junctions, irrespective of follicle stage, were located on the outer surface of the oocyte cytoskeleton. Cx43 was detected in granulosa cells of all follicle stages, beginning with distinct spots in resting primordial follicles. The estimated number of Cx43 gap junctions per granulosa cell increased significantly with follicle development, in particular in the transition from pre-antral to the antral stage. A subpopulation of Cx43 in the outer part of the zona pellucida was identified and it is suggested these Cx43 gap junctions connect cumulus trans-zonal projections. Together, these data suggests specific roles for Cx37 and Cx43 in folliculogenesis and offers new insights in patterns of intercellular communication of the mouse follicle.

The role of thecal androgen production in the regulation of estradiol biosynthesis by dominant bovine follicles during the first follicular wave1,2

The first wave of follicular development following ovulation in cattle is characterized by selection and growth of a large, estrogenic dominant follicle. After the follicle becomes morphologically dominant, concentrations of estradiol in its follicular fluid decrease abruptly. The purpose of this study was to determine whether this decrease in estrogen production is caused by an insufficient supply of androgen from theca interna or decreased aromatization of androgen precursor by granulosa cells. Dominant follicles were collected from Holstein heifers on d 4, 6, or 8 of the first follicular wave (n = 5/d). Amounts of 17alpha-hydroxylase mRNA in theca interna were sevenfold higher (P < 0.01) on d 4 than on d 8. After 3 h in culture, secretion of androstenedione by theca interna collected on d 4 (236 +/- 44 pg/microg of protein) tended to be lower (P = 0.055) compared with d 6 (517 +/- 162 pg/microg protein) and was lower (P < 0.05) compared with d 8 (387 +/- 51 pg/microg of protein). In granulosa cells, amounts of aromatase mRNA decreased (P < 0.05) on d 8 compared with d 6 but not d 4. In vitro secretion of estradiol was higher in granulosa cells collected on d 4 (3.5 +/- 0.8 ng/[10(5) cells x 3 h]) compared with d 6 (1.8 +/- 0.6 ng/[10(5) cells x 3 h]; P < 0.05) and tended to be higher on d 4 than on d 8 (2.2 +/- 0.2 ng/[10(5) cells x 3 h]; P = 0.058). We conclude that the decrease in estradiol production observed during atresia of the dominant follicle is not due to lack of androgen substrate for aromatization or downregulated expression of the aromatase gene, but may be the direct result of decreased activity of the aromatase enzyme within granulosa cells.

Denervation of the porcine ovaries performed during the early luteal phase influenced morphology and function of the gonad

We studied both morphology and steroidogenic activity of ovaries in gilts after bilateral surgical denervation performed on day 3 of the estrous cycle. Blood samples were collected from day 4 of the first estrous cycle to day 11 of the subsequent cycle. Denervation resulted in a dramatic reduction in the number or in the disappearance of tyrosine hydroxylase/dopamine-beta-hydroxylase- and/or neuropeptide Y-immunoreactive nerve fibres. On day 11 of the second cycle, the number of follicles (3-6 mm in diameter) was lower (p<0.001) in the denervated ovaries, while corpora lutea were not present. Neurectomy also led to a decrease in the concentrations of progesterone, androstendione and 17beta-estradiol in the follicular fluid originated from small (1-3 mm in diameter) as well as medium-sized follicles (3-6 mm in diameter). Similar to follicular fluid, concentration of androstendione in the follicular wall of medium-sized follicles decreased in experimental gilts in comparison to that of control animals. In addition, plasma concentrations of LH and steroid hormones were lower in the control than in the experimental group. Our results show that denervation of ovaries during the early luteal phase of the estrous cycle in gilts resulted in the changes in both morphology and steroidogenic activity. These results confirm the important role of the peripheral nerves in the function of ovaries.

Expression of bone morphogenetic protein2 (BMP2), BMP4 and BMP receptors in the bovine ovary but absence of effects of BMP2 and BMP4 during IVM on bovine oocyte nuclear maturation and subsequent embryo development

Bone morphogenetic proteins (BMPs) have been implicated in the regulation of ovarian follicular development and are promising candidates to apply in IVM and IVF protocols. We investigated the expression of BMP2, BMP4 and BMP receptors in bovine ovaries and the effects of BMP2 and BMP4 during oocyte maturation on bovine IVM. Reverse transcription polymerase chain reaction studies with antral follicles showed the expression of BMPR-IA, BMPR-IB, ActR-IA, ActR-IIB, BMPR-II and BMP4 mRNA in all follicular compartments, while BMP2 mRNA was generally restricted to theca and cumulus tissue. Immunohistochemistry demonstrated the presence of BMPR-II in oocytes and granulosa cells of preantral follicles but only in oocytes of antral follicles. The immunostaining of BMP2 and BMP4 was limited to theca interna and approximately 25% of oocytes of antral follicles. Exogenously added BMP2 or BMP4 to IVM medium did not affect oocyte nuclear maturation, cumulus cell expansion, nor blastocyst formation following IVF. It is concluded that a BMP-signaling system, consisting of BMP2, BMP4, type II and I receptors, is present in bovine antral follicles and that this system plays a role in development and functioning of these follicles rather than in final oocyte maturation and cumulus expansion.

Melatonin seems to be a mediator that transfers the environmental stimuli to oocytes for inheritance of adaptive changes through epigenetic inheritance system

Possibility of inheritance of epigenetic modifications have led us to consider that adaptive geographic variations in humans may result from interactions between environmental factors and epigenetic inheritance system. In this system melatonin seems to be a mediator that transfers the environmental stimuli to germ cells (oocytes). While environmental factors produce modifications in the body, they simultaneously induce epigenetic modifications in the oocytes with the help of melatonin, and these changes are inherited to offspring. In this way, adaptive changes could be passed on to the next generation. This kind of heritable long-term changes is generally labeled biological adaptation. But, how can melatonin cause epigenetic changes in oocytes? We suggest that melatonin induces epigenetic modifications by affecting the nuclear melatonin receptors that can in turn change the superstructure of DNA. It was previously suggested that biological adaptation is limited to neural crest derivatives such as, craniofacial tissues, melanocytes, and structures related to stature, hair form and body proportions. Thus, inheritance of adaptive changes is possible only where environmental factors affect the neural crest derivatives, including the cells that produce the next generation.

[Comparison of 4 anesthetic techniques for in vitro fertilization]

Little is known of the effect on oocytes of anesthesia administered during retrieval. The main objective of this study was to compare the prolactin and stress hormone responses to surgical stimulus under 4 anesthetic techniques and to determine whether there is an effect of technique on the number and quality of oocytes retrieved.

METHODS

We designed a clinical trial to determine the plasma and follicular levels of prolactin and cortisol in patients in an assisted reproduction program. The patients were randomized to 3 anesthetic groups: general anesthesia, spinal anesthesia, or sedation with alfentanil and midazolam plus paracervical block. Patients were consecutively assigned to the fourth group to receive sedation with remifentanil plus paracervical block.

RESULTS

We studied 90 patients. The patients receiving general anesthesia had the greatest increase in prolactin by the end of the procedure. Follicular cortisol increased in the paracervical block group in which remifentanil was used for sedation. The only significant difference between groups was seen for the rate of gestation of 0% in the group receiving sedation with alfentanil and midazolam before a paracervical block. Adverse effects were few with all the techniques. All patients reported a high degree of satisfaction.

CONCLUSIONS

Plasma increases in prolactin and hormonal responses to follicular puncture were fully attenuated by spinal anesthesia and partially attenuated by the techniques requiring sedation. None of the anesthetic techniques proved harmful to oocytes or embryos. Nor was the effectiveness of the in vitro fertilization technique affected by any of the anesthetic techniques studied.

Early human preantral follicles have relaxin and relaxin receptor (LGR7), and relaxin promotes their development

The regulatory mechanisms of early follicle development are not clearly understood. Although relaxin is a peptide that controls cell proliferation and differentiation in many tissues, its role in human follicular development is unclear. In this study we cultured slices of human ovarian cortical tissue in the presence and absence of recombinant human relaxin. Ovarian tissue was obtained by biopsy during gynecological laparotomy or laparoscopy (14 women; mean age +/- sem, 29.0 +/- 6.1 yr; range, 17-37 yr). A significantly higher proportion of secondary follicles (14.5% vs. 5.0% in the control group; P < 0.01) and a significantly decreased proportion of primordial follicles (30.1% vs. 47.4% in the control group; P < 0.05) were found in tissues cultured with relaxin for 7 d. Immunocytochemical studies with the anti-C-peptide of prorelaxin and antirelaxin antibodies revealed the localization of relaxin in the oocyte and in flat pregranulosa and granulosa cells of primordial, primary, and secondary follicles. The presence of the relaxin receptor LGR7 was observed in flat pregranulosa and granulosa cells of primordial, primary, and secondary follicles by immunocytochemical and in situ hybridization analyses. These results suggest that relaxin plays a role through its receptor during the early stage of follicle development.

Cloning and expression of the yolk protein of the tsetse fly Glossina morsitans morsitans

Two major families of nutritional proteins exist in insects, namely the vitellogenins and the yolk proteins. While in other insects only vitellogenins are found, cyclorraphan flies only contain yolk proteins. Possible sites of yolk protein synthesis are the fat body and the follicle cells surrounding the oocyte. We report the cloning of the yolk protein of the tsetse fly Glossina morsitans morsitans, a species with adenotrophic viviparity. The tsetse fly yolk protein could be aligned with other dipteran yolk proteins and with some vertebrate lipases. In contrast to the situation in most fly species, only a single yolk protein gene was found in the tsetse fly. Northern blot analysis showed that only the ovarian follicle cells, and not the fat body represents the site of yolk protein synthesis.

Localization and temporal regulation of tissue inhibitors of metalloproteinases 3 and 4 in bovine preovulatory follicles

The matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are potential regulators of the focalized extracellular matrix degradation required for ovulation. The objectives of the present study were to determine localization and temporal regulation of TIMP-3 and TIMP-4 mRNA and protein in bovine preovulatory follicles. Ovaries containing preovulatory follicles were collected at 0, 12 and 20 h after GnRH injection for real-time PCR quantification of TIMP-3 and TIMP-4 mRNAs and immunohistochemical localization studies. Additional samples collected at 0, 6, 12, 18 and 24 h post GnRH injection were subjected to Western analysis to determine temporal changes in TIMP-3 and TIMP-4 proteins in the apex and base of preovulatory follicles. Results indicate the gonadotropin surge regulates TIMP-3 and TIMP-4 expression. TIMP-3 and TIMP-4 mRNAs increased within 12 h after GnRH injection. TIMP-3 protein was localized to granulosal and thecal layers of preovulatory follicles and adjacent ovarian stroma, whereas TIMP-4 immunoreactivity was localized to granulosal and thecal cells and ovarian blood vessels. Amounts of TIMP-3 and TIMP-4 proteins in the follicular apex peaked within 12 h post GnRH injection and subsequently declined by 24 h. However, amounts of TIMP-3 and TIMP-4 proteins in the base were not elevated after GnRH administration. Results demonstrate that mRNA and protein for both TIMP-3 and TIMP-4 are increased in bovine preovulatory follicles following the gonadotropin surge. Coordinate expression of TIMPs and MMPs may help regulate the extracellular matrix remodeling characteristic of the ovulatory process.

Molecular cloning of porcine growth differentiation factor 9 (GDF-9) cDNA and its role in early folliculogenesis: direct ovarian injection of GDF-9 gene fragments promotes early folliculogenesis

Growth differentiation factor-9 (GDF-9) is a growth factor secreted by oocytes in growing ovarian follicles. To investigate the ovarian function of GDF-9 in pigs, we first cloned porcine GDF-9 complementary DNA (cDNA), and then injected its gene fragments into the ovary in gilts. Porcine GDF-9 has open reading frame (ORF) homologies of 81.4%, 84.6%, 84.2%, 72.7% and 72.6% with its human, bovine, ovine, rat and mouse counterparts respectively. Regarding the deduced amino-acid sequence of the mature protein, the corresponding homologies reach 92.1%, 97.8%, 97.0%, 89.6% and 88.1% respectively. To investigate the role of GDF-9 in early folliculogenesis, the ovaries of 2-month-old prepubertal gilts were injected with GDF-9 gene fragments. The injection of porcine GDF-9 gene fragments resulted in an increase in the number of primary, secondary and tertiary follicles, concomitant with a decrease in the number of primordial follicles. These results indicated that exogenous GDF-9 can promote early folliculogenesis in the porcine ovary, and that a technique for direct ovarian injection of GFD-9 gene fragments may contribute to a novel therapy for prevention and treatment of infertility associated with ovarian dysfunction.

Ovarian follicle vascularization in fasted pig

The authors have investigated in the different classes of ovarian follicles the vascular area, the blood vessel distribution, the vascular endothelial growth factor (VEGF) mRNA expression and the VEGF secretion during equine chorionic gonadotropin (eCG) induced follicle growth in prepubertal gilts fed ad libitum or fasted. Immunohistochemistry staining of Von Willebrand factor showed that fasting caused a dramatic increase in the vascular area of medium-large tertiary follicles. The increase involved the two concentric vessel networks and the area between them that, becoming crossed by several anastomosis, modified the whole vessel architecture. Both in situ hybridization and in vitro culture experiments demonstrate that granulosa cells from medium-large follicles are engaged in a copious VEGF production upon eCG stimulation both in gilts fed ad libitum or fasted. More surprisingly, the production of VEGF becomes diffuse amongst theca cells of fasted animals thus recruiting a compartment that in condition of normal feeding regimen appears nearly quiescent. In conclusion, the data presented describe a local angiogenic process that develops in the follicle wall of growing antral follicle in case of acute severe food restriction. The mechanism, essentially confined to follicles that potentially approach ovulation, appears to assume the meaning of a local compensatory mechanism that may help maintaining adequate nutrient delivery to follicles that undergo ovulation.