Features of follicle-stimulating hormone-stimulated follicles in a sheep model: keys to elucidate embryo failure in assisted reproductive technique cycles

Associations among the largest follicle, preovulatory estradiol concentrations, and predominant vaginal epithelial cells at the completion of hormonal ovarian stimulation for fixed-time artificial insemination in goats

The objective of the present study was to investigate the association among the largest follicle (LF), preovulatory estradiol (E2), and predominant vaginal epithelial cell at the completion of hormonal ovarian stimulation for fixed-time artificial insemination (FTAI) in goats. Thirty-seven crossbred Boer does received gonadotropin-releasing hormone (GnRH) and intravaginal progesterone (P4)-releasing devices (day 0). On day 5, P4 devices were removed and does received prostaglandin F2α and equine chorionic gonadotrophin. On day 7, does received GnRH, and FTAI was undertaken. On day 7, does were divided into three groups, i.e. small-sized (3-3.9 mm; n = 5), medium-sized (4-4.9 mm; n = 8), and large-sized (≥5 mm; n = 24) according to the diameter of the ovarian LF; follicular characteristics (number and diameter) were identified, and blood samples and vaginal smears were collected. The average diameters of total antral follicles and LF and the percentage of superficial cell were greatest in large-sized LF does (p < .01). The average diameters of total antral follicle (r = .68) and LF (r = .71), number of preovulatory follicle (r = .58), and plasma E2 concentrations (r = .61) were positively correlated with the percentage of superficial cells (p < .01). The likelihood of a pregnancy outcome after the FTAI increased by 13.71 times in does with a greater average diameter of antral follicle, 14.18 times with emergence of a large preovulatory follicle, and 36.83 times with a higher percentage of vaginal superficial cells (p < .01). It was concluded that there is a relationship between the cell types of the vaginal epithelium, the diameters of the largest ovarian follicles, and the concentration of E2 in goats subjected to FTAI protocols.

Synchronization of follicular wave emergence does not improve embryonic yield in superovulated ewes

The present study aimed to investigate the effects of a combination of progesterone with different doses of E-17β on following end points: (1) ovarian follicular dynamics and emergence of a new follicular wave, and (2) superovulatory response and embryo yield. In Experiment 1, 28 ewes were randomly divided into four groups (n = 7) to receive either 2.0 mg, 1.0 mg, 0.5 mg or none E-17β one day after insertion of a progesterone device. The different doses of estradiol similarly delayed the moment of follicular emergence (overall mean = 3.1 ± 1.0 days vs. control group = 0.86 ± 1.0 days; P < 0.01), but the emergence of the new wave showed greater synchronization with the 0.5 mg dosage of E-17β. In Experiment 2, sixty-two donor ewes received an internal progesterone release device (day -1) for 7 d and 1 d after the insertion of this device (day 0) were allocated randomly to receive 0.5 mg of E-17β or only the vehicle (control group). Superstimulation was initiated on day 3 with the administration of 133 mg of pFSH in eight decreasing doses. Contrary to expectations, the protocol with the administration of 0.5 mg E-17β did not improve the percentage of donors with > 2 CL, the number of CL and the production of embryos (P > 0.05). It was concluded that the combination of progesterone and 0.5 mg E-17β was more efficient in synchronizing the emergence of the new follicular wave, however this approach seems to be unnecessary in ewe’s superovulation programs.

Follicular dynamics and in vivo embryo production in Santa Inês ewes treated with smaller doses of pFSH

To evaluate follicular dynamics, there was assessment of superovulatory response and in vivo embryo production in ewes treated with relatively smaller doses of exogenous pFSH than typically used in combination with a dose of eCG at the beginning of the gonadotropin treatment period. Santa Inês ewes (n = 24) were randomly divided into three groups, based on mg dose of pFSH administered: G200 (n = 8), G133 (n = 8) and G100 (n = 8) in eight decreasing doses at 12 -h intervals. All ewes were treated with 300 IU of eCG concomitantly starting with first pFSH administration. Ovulatory follicular dynamics and follicular wall vascularization (FWV) were evaluated using a B-mode and color Doppler ultrasonic machine, respectively. Superovulatory response and embryo production were evaluated 6 days after estrous detection. In the G200 group, the preovulatory follicle size (PFS) were less (P <  0.05), ovulation time later (P <  0.05), and PFS rate greater (P <  0.05); while in the G100 group ovulation rate, and number and percentage of unfertilized eggs were greater (P <  0.05) than in the G133 group (P <  0.05). Number and percentage of viable embryos were greater in the G200 and G100 compared to G133 group (P <  0.05). The dose of 100 mg of FSH was as efficacious as the traditional dose of 200 mg, in combination with a dose of eCG, for superovulatory response and viable embryo production but there was a greater percentage of unfertilized eggs with this treatment.

Developmental programming: rescuing disruptions in preovulatory follicle growth and steroidogenesis from prenatal testosterone disruption

BACKGROUND

Prenatal testosterone (T) excess from days 30-90 of gestation disrupts gonadotropin surge and ovarian follicular dynamics and induces insulin resistance and functional hyperandrogenism in sheep. T treatment from days 60-90 of gestation produces a milder phenotype, albeit with reduced fecundity. Using this milder phenotype, the aim of this study was to understand the relative postnatal contributions of androgen and insulin in mediating the prenatal T induced disruptions in ovarian follicular dynamics.

METHODS

Four experimental groups were generated: 1) control (vehicle treatment), 2) prenatal T-treated (100 mg i.m. administration of T propionate twice weekly from days 60-90 of gestation), 3) prenatal T plus postnatal anti-androgen treated (daily oral dose of 15 mg/kg/day of flutamide beginning at 8 weeks of age) and 4) prenatal T and postnatal insulin sensitizer-treated (daily oral dose of 8 mg/day rosiglitazone beginning at 8 weeks of age). Follicular response to a controlled ovarian stimulation protocol was tested during their third breeding season. Main outcome measures included the determination of number and size of ovarian follicles and intrafollicular concentrations of steroids.

RESULTS

At the end of the controlled ovarian stimulation, the number of follicles approaching ovulatory size (≥6 mm) were ~35 % lower in prenatal T-treated (6.5 ± 1.8) compared to controls (9.8 ± 2.0). Postnatal anti-androgen (10.3 ± 1.9), but not insulin sensitizer (5.0 ± 0.9), treatment prevented this decrease. Preovulatory sized follicles in the T group had lower intrafollicular T, androstenedione, and progesterone compared to that of the control group. Intrafollicular steroid disruption was partially reversed solely by postnatal insulin sensitizer treatment.

CONCLUSIONS

These results demonstrate that the final preovulatory follicular growth and intrafollicular steroid milieu is impaired in prenatal T-treated females. The findings are consistent with the lower fertility rate reported earlier in these females. The finding that final follicle growth was fully rescued by postnatal anti-androgen treatment and intrafollicular steroid milieu partially by insulin sensitizer treatment suggest that both androgenic and insulin pathway disruptions contribute to the compromised follicular phenotype of prenatal T-treated females.

Diagnostic applications for inhibin and activins

Inhibin and activins play major roles as paracrine and autocrine signaling molecules in reproduction and development where the main emphasis has been placed in developing potential diagnostic applications. While a role for activin assays in diagnostics has so far been unfounded, ELISAs specific for the biologically active inhibin A and B dimers, and for free inhibin alpha subunits, alone or in combination have found some specific diagnostic applications. Addition of inhibin A to the triple test for Down syndrome in the second trimester of pregnancy, measurement of total inhibin as a marker of certain forms of ovarian cancer in specific circumstances, and inhibin B for male fertility are useful diagnostics. A review of the evidence so far suggests that other applications for inhibin and activin assays have yet to be confirmed, or translated into reliable tools for clinical practice.

The interaction between ovulation rate and embryo survival in determining prolificacy of different strains of obese swine with gene polymorphisms for leptin receptors

The Mediterranean Iberian pigs show a clear predisposition to obesity, due to gene polymorphisms for leptin receptors, and a lower prolificacy when compared with lean breeds. Previous studies indicate a bimodal effect of obese genotypes on prolificacy; either by lowering ovulation rate or by increasing embryo losses when compared with lean genotypes. The present study aimed to discriminate the relative influence of both parameters by comparing strains of Iberian females with different prolificacy (14 original purebred Retinto, group R, and 20 Retinto × Torbiscal females selected for prolificacy, group RT). Examination of ovaries around Day 40 of pregnancy showed a higher ovulation rate in the RT than in the R sows (21.5 ± 1.4 versus 12.3 ± 1.0 corpora lutea, respectively; P < 0.0005). However, there was a higher incidence of implantation failures and early embryo losses in the RT females (42.9 versus 14% for the group R; P < 0.005). Thus, the number of viable embryos was higher in the RT line (10.8 ± 0.5 versus 7.6 ± 0.7 in the R sows, P < 0.0005), but also limited when compared with ovulation rate. Conversely, this effect was not found in the R sows; however, prolificacy of these females was limited by higher embryo mortality (24.1 versus 4.6% for RT females). In conclusion, the present study evidences dissimilar reproductive behaviour among strains of the Iberian pig differing in prolificacy and confirms previous evidences suggesting the existence of intrinsic factors avoiding excessively large litter sizes in Iberian females.

Ultrasonographic imaging in small ruminant reproduction

CONTENTS

Ultrasonography is a simple, reliable and non-invasive imaging technique without secondary effects. Application of ultrasonography in veterinary practice, and specifically in small ruminants, has developed to become the most efficient diagnostic tool for managing reproduction. The objectives of current revision are to offer an overview, after a short reminder of equipment and techniques for imaging genitalia in small ruminants, of the uses and utility of ultrasonography for the evaluation of physiological and pathological conditions in males and females and for the application of assisted reproductive technologies.

Substantiation of ovarian effects of leptin by challenging a mouse model of obesity/type 2 diabetes

The goal of the current was to elucidate if treatment with gonadotrophins and leptin can circumvent infertility in obese mice and to establish whether reproductive effects of leptin are influenced at the hypothalamus-hypophysis or ovarian level by using a leptin deficient mouse model of obesity/type 2 diabetes (ob/ob) treated with leptin. The ovulatory response and the fertilization success were compared with the results obtained in ob/ob dams pretreated with a gonadotrophin-replacement therapy or in two groups (ob/ob and wild-type) of control non-pretreated females. The number of corpora lutea was significantly lower in control ob/ob mice than in wild-type dams. Treatment with gonadotrophin-replacement therapy did not increase significantly the ovulation rate in ob/ob, but the administration of leptin-replacement treatment allowed the authors to obtain a number of corpora lutea and oocytes/zygotes similar to those obtained in wild-type females. Furthermore, the leptin supply succeeded in producing fertilized zygotes, although in a lower number than found in the wild-type control. Thus, the hypogonadotrophic state in obese mice may be circumvented by the administration of a gonadotrophin-replacement therapy combined with a protocol for controlled ovarian stimulation, but fertile ovulations are only obtained after applying leptin-replacement therapy. Current results strongly support the existence of direct local effects of leptin on the ovary.