Estradiol and progesterone have been recognized as important mediators of reproductive events in the female mainly via binding to their receptors. This study aimed to characterize the immunolocalization of the estrogen receptor alfa (ERα), estrogen receptor beta (ERβ) and progesterone receptor (PR) in the ovarian follicles of the lizard Sceloporus torquatus. The localization of steroid receptors has a spatio-temporal pattern that depends on the stage of follicular development. The immunostaining intensity of the three receptors was high in the pyriform cells and the cortex of the oocyte of previtellogenic follicles. During the vitellogenic phase, the granulosa and theca immunostaining was intense even with the modification of the follicular layer. In the preovulatory follicles, the receptors were found in yolk and additionally, ERα was also located in the theca. These observations suggest a role for sex steroids in regulating follicular development in lizards, like other vertebrates.

The aim of this study was to evaluate the effect of 1 µmol/l zearalenone (ZEN) and 1 µmol/l matairesinol (MAT), alone or in combination, on the morphology of in vitro-cultured ovarian preantral follicles. Ovaries from four adult sheep were collected at a local slaughterhouse and fragmented, and the ovarian pieces were submitted to in vitro culture for 3 days in the presence or absence of the test compounds. The morphology of primordial and primary follicles was impaired by ZEN. The plant lignan MAT alone did not maintain the morphology of the ovarian follicles; its combination with ZEN counteracted the negative effects observed when follicles were cultured in the presence of the mycotoxin alone. However, MAT was not able to promote the in vitro development of the ovarian follicles.

Tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) are cytokines that are involved in the development, proliferation and apoptosis of ovarian follicular cells in domestic mammals. The expression of these cytokines in various follicular compartments, depending on the stage of follicle development, demonstrates their involvement in the control of primordial follicle growth up to the preovulatory stage. The mechanism of action of these factors depends on the presence of their receptors that transduce their biological actions. This review shows the expression sites of TNF-α, IL-1β and their receptors in ovarian follicles, and discusses the mechanism of action of these cytokines during follicle development, oocyte maturation and ovulation in domestic animals.

Piglet birth weight and within-litter birth weight variation are important for piglet survival and growth. Pre-mating diets may improve IGF-1 and follicle development during the weaning-to-oestrus interval (WEI) and subsequent piglet birth weight. The objective of this study was to modulate IGF-1 concentration during late lactation and the WEI of young sows by using specific pre-mating diets supplemented with microfibrillated cellulose (MF), l-carnitine (LC) or l-arginine (AR). A further objective was to investigate the relationship between IGF-1 and subsequent follicle development and oestrus and ovulation characteristics. In total, 56 first-parity and 20 second-parity sows in three consecutive batches were used for this experiment. Sows received daily either wheat (CON) or wheat plus MF, LC or AR at one of two supplementation levels (low and high) during last week of lactation and WEI. From weaning onwards, follicle and corpus luteum (CL) diameters were repeatedly measured with ultrasound. Blood samples were collected during the WEI for IGF-1 and on day 21 of pregnancy for progesterone analyses, respectively. Insulin-like growth factor-1 concentration, follicle diameter, oestrus and ovulation characteristics and CL diameter were not affected by pre-mating diets. Low IGF-1 class (≤156 ng/ml, N = 22) sows had smaller follicles at weaning (3.5 v. 3.8 mm, P < 0.05) and a longer weaning-to-ovulation interval (147.2 v. 129.8 h, P < 0.05) than high IGF-1 class sows. In first-parity sows, high loin muscle depth (LM) loss sows (≥8%, N = 28) had lower IGF-1 concentrations at weaning (167 v. 214 ng/ml, P < 0.05) compared to low LM loss sows (<8%, N = 28). However, after weaning, IGF-1 concentrations increased and did not differ between high LM loss and low LM loss sows. In conclusion, the different supplemented compounds in pre-mating diets did not improve IGF-1 concentrations around weaning in young sows. Furthermore, high body condition loss caused lower IGF-1 concentrations at weaning, but these levels rapidly recovered after weaning and were related to follicle development and the interval from weaning to ovulation.

Androgens may directly modulate early ovarian follicular development in preantral stages and androgen excess before puberty may disrupt this physiological process. Therefore, the aim of this study was to investigate the dynamics of follicular morphology and circulating androgen and estradiol levels in prepubertal Wistar rats acutely exposed to androgens. Prepubertal female Wistar rats were distributed into three groups: control, equine chorionic gonadotropin (eCG) intervention and eCG plus dehydroepiandrosterone (DHEA) intervention (eCG+DHEA). Serum DHEA, testosterone and estradiol levels were determined, and ovarian morphology and morphometry were assessed. The eCG+DHEA group presented increased serum estradiol and testosterone levels as compared with the control group (P<0.01), and higher serum DHEA concentration v. the eCG-only and control groups (P<0.01). In addition, the eCG+DHEA group had a higher number of, and larger-sized, primary and secondary follicles as compared with the control group (P<0.05). The eCG group presented intermediate values for number and size of primary and secondary follicles, without significant differences as compared with the other two groups. The number of antral follicles was higher in the eCG+DHEA and eCG groups v. controls (P<0.05). The number of primordial, atretic and cystic follicles were similar in all groups. In conclusion, the present experimental model using an acute eCG+DHEA intervention was useful to investigate events involved in initial follicular development under hyperandrogenic conditions, and could provide a reliable tool to study defective follicular development with possible deleterious reproductive consequences later in life.

Cortical tissues containing only primordial and primary follicles, or secondary follicles 140-190 μm in diameter, were collected from bovine ovaries and xenografted under the kidney capsules of female severe combined immunodeficient (SCID) mice. Histological examination revealed that all grafts were well vascularised and contained surviving follicles at 4 or 6 weeks after grafting. Primordial and primary follicles survived but did not develop beyond the one-layer stage. Secondary follicles, on the other hand, had formed antra at 4 weeks after grafting. The mean diameter of secondary follicles, which was 165.2 ± 17.0 μm (n = 42) before grafting, had developed to 442.9 ± 77.9 μm (n = 37) and 592.9 ± 116.0 μm (n = 45) in diameter at 4 and 6 weeks after grafting, respectively. The mean diameter of oocytes, which was 55.1 ± 4.9 μm (n = 42) before grafting, also increased significantly (4 weeks: 105.6 ± 6.3 μm; 6 weeks: 122.2 ± 2.6 μm; p < 0.05). Oocytes were recovered from follicles that had developed to more than 400 μm in diameter after 6 weeks, and were subjected to subsequent mature culture. Of these oocytes, 34% (11/32) resumed meiosis and 6% (2/32) matured to the second metaphase. Follicular fluid in bovine antral follicles developed in SCID mice had the 69 kDa protein, which was detected by anti-mouse albumin antibody but not by anti-bovine albumin antibody in immunoblotting analysis. These results demonstrated that bovine secondary follicles develop to the antral stage in SCID mice, and that the oocytes in the follicles acquire the meiotic competence.

We wished to establish the frequency, regularity and laterality of multiple ovulation in mothers of dizygotic (DZ) twins and controls. Subjects had regular menses and were not using oral contraceptives. Ovarian ultrasound scans were taken over a number of cycles in 21 mothers of DZ twins and 18 controls (including 13 mothers of monozygotic [MZ] twins). Multiple large follicles (≥ 12 mm diameter) were seen significantly more frequently in mothers of DZ twins (13/21 mothers, 24/77 cycles, average ± SE follicles/cycle 1.34 ± 0.11) than controls (2/18 mothers, 3/31 cycles, average 1.10±0.08). Both ipsilateral and contralateral multiple follicles were observed. In one case a mother of DZ twins showed multiple large follicles in 7 out of 10 cycles in which she was scanned, including both ipsi-and contralateral patterns of occurrence.