Morphology and morphometry of preantral follicles, and immunolocalization of angiogenic factors in ovarian tissue from the neotropical primate Sapajus apella

Effects of Chronically Exogenous Oxytocin on Ovary and Uterus: A Comparison of Intraperitoneal and Intranasal Administration

Oxytocin (OT) has been studied as a therapeutic neuropeptide in various diseases, but its effect on the ovary and uterus is not fully known. This study investigates the effects of intranasal and intraperitoneal OT administration on ovaries and uterus in rats. Four experimental groups were created using 7-week-old Sprague Dawley-type female rats: Control (Ctrl), oxytocin-intraperitoneal (0.1µg/day) (OT-IP), oxytocin-intranasal (0.05µg/day) (OT-IN1), and oxytocin-intranasal (0.1µg/day) (OT-IN2). The blood, the ovarian, and the uterus were collected at the end of the 28th day of OT administration. Afterward, histological and biochemical analyses were performed. We observed that the Graaf follicles were higher in both OT-IN2 and OT-IP groups compared to the Ctrl group. Moreover, the corpus luteum was increased only in the OT-IN2 group. Ki-67, CD31, VEGF, and TGF-ß immunostaining showed no significant change in the ovary. In contrast, Ki-67, VEGF, and OTR expressions demonstrated significant alterations in the uterus. Furthermore, TGF-ß immunohistochemistry and the histopathologic score did not reveal the statistical change in the uterus. Serum hormone levels showed that the anti-Müllerian hormone increased in all OT groups vs. the Ctrl. OT-IP showed an increment of follicle-stimulating hormone and estradiol decrement. There was a decrease in serum E2 levels, although the Graafian follicle number increased in OT-IP groups compared to the Ctrl group. However, luteinizing hormone, gonadotropin-releasing hormone, progesterone, testosterone, OT levels, and oxidative stress index did not reveal any statistical difference. Accordingly, the intranasal route may have beneficial effects compared to the intraperitoneal route regarding exogenous OT administration-related studies. In conclusion, we reported that exogenous OT increases the follicle reserve and may cause histological changes in the reproductive system of female rats.

The vascular endothelial growth factor (VEGF) system as a key regulator of ovarian follicle angiogenesis and growth

The vascular endothelial growth factor-A (VEGFA) system is a complex set of proteins, with multiple isoforms and receptors, including both angiogenic (VEGFxxx, VEGFR2) and antiangiogenic members (VEGFxxxb, VEGFR1 and soluble forms of VEGFR). The members of the VEGF system affect the proliferation, survival, and migration of endothelial and nonendothelial cells and are involved in the regulation of follicular angiogenesis and development. The production of VEGF by secondary follicles stimulates preantral follicular development by directly affecting follicular cells and promoting the acquisition of the follicular vasculature and downstream antrum formation. Additionally, the pattern of expression of the components of the VEGF system may provide a proangiogenic milieu capable of triggering angiogenesis and stimulating follicular cells to promote antral follicle growth, whereas, during atresia, this milieu becomes antiangiogenic and blocks follicular development.

Follicular Atresia, Cell Proliferation, and Anti-Mullerian Hormone in Two Neotropical Primates (Aotus nancymae and Sapajus macrocephalus)

This study evaluated the follicular atresia, cell proliferation, and anti-Mullerian hormone action in Aotus nancymae and Sapajus macrocephalus during three sexual phases (follicular, luteal, and gestational). Follicular quantification and immunolocalization of Caspase-3 protein, B-cell lymphoma 2 (BCL-2), proliferating cell nuclear antigen (PCNA), and anti-Mullerian hormone (AMH) were performed. A significant difference in the quantification between preantral and antral follicles, with a progressive decrease in the antrals, was identified. Protein and hormonal markers varied significantly between follicle cell types (A. nancymae p = 0.001; S. macrocephalus, p = 0.002). Immunostaining in the preantral and antral follicles was present in all sexual phases; for Caspase-3, in granulosa cells, oocytes, and stroma; for BCL-2, in granulosa cells, oocytes, and theca; and for PCNA and AMH, in oocytes and granulosa cells. The immunostaining for Caspase-3 was more expressive in the preantral follicles (follicular phase, p < 0.05), while that for BCL-2 and PCNA was more expressive in the antral follicles of the follicular phase. The AMH was more expressive in the primary and antral follicles of nonpregnant females, in both the follicular and luteal phases. Our results contribute to understanding the ovarian follicular selection, recruitment, and degeneration of these species.

Effects of in vitro exposure of sheep ovarian tissue to zearalenone and matairesinol on preantral follicles

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.

Induced-damages on preantral follicles by withanolide D, a potent chemotherapy candidate are not attenuated by melatonin

Withanolide D (WD) has been investigated as an antineoplastic drug. This study aimed to evaluate whether melatonin (MT) could attenuate toxic effects on preantral follicles enclosed in the ovarian cortex (experiment 1 - E1) or on isolated secondary follicles (experiment 2 - E2) exposed to WD. For E1, ovarian cortex was incubated for 48 h to: (1) α-MEM⁺; (2) α-MEM⁺ plus 6 μM WD; (3) α-MEM⁺ plus 3 mmol/L MT or (4) α-MEM⁺ plus WD and MT. For E2, secondary follicles were exposed for until 96 h in. (1) only to basic medium (α-MEM⁺⁺/α-MEM⁺⁺); (2) α-MEM⁺⁺ plus 3 mmol/L MT (MT/MT); (3) α-MEM⁺⁺ until 48 h, followed by more 48 h in 6 μM WD (α-MEM⁺⁺/WD) or (4) a pre-exposure to MT for until 48 h, followed by more 48 h of exposure to WD plus MT (MT/MT + WD). The main results obtained showed that exposure to drugs caused damage to follicular morphology (WD or WD + MT) and diameter (WD) in the ovarian cortex or in isolated follicles. In pre-antral follicles in situ, ATM expression increased in the presence of WD, MT or association. As for the secondary follicles, ATM and γH2AX were immunostained in the granulosa and theca cells and oocytes in all treatments. TAp63α was immunostained in follicles included in the ovarian cortex and in isolated follicles. We conclude that melatonin did not provide protection and could have enhanced the toxic effect of WD to follicles surrounded or not by the ovarian cortex.

Interference of fixatives and fixation period on the morphologic analysis of ovarian preantral follicles

Ovine ovarian fragments (3 × 3 × 1 mm) were fixed in neutral buffered formalin (NBF), Carnoy's solution (CAR), Davidson's solution (DAV), or paraformaldehyde (PFA) for 12 h or 24 h. After this fixation time, each fragment was prepared for histological analysis. Although fixative and fixation period did not affect follicular and stromal cells density, the percentages of morphologically normal primordial and primary follicles was affected by the fixative type and period of fixation. Paraformaldehyde was not indicated as a fixative for ovarian fragments. Formalin was a suitable fixative only when the period of fixation was 12 h, while Carnoy was efficient after a fixation period of 24 h. In conclusion, the most indicated fixative for the morphological evaluation of ovarian preantral follicles was DAV, regardless of the fixation period, that is 12 or 24 h.

Reproductive biology of owl (Aotus spp.) and capuchin (Sapajus spp.) monkeys

Studies related to morpho-physiology improve the understanding of biological mechanisms in non-human primates (NHP), contributing to research in several areas, especially those of assisted reproduction and biomedicine. The genera Aotus and Sapajus are important considerations in conducting studies related to reproductive biology and biomedical research, where animals of these genera can serve as models for species with vulnerable conservation status. The reproductive functions of animals of these genera can be used in conducting studies with other NHP species, for which biological material is difficult to access. The aim in conducting the current review was to compile the scientific literature on the biology and reproductive aspects of these two genera, to provide a for a greater understanding of these topics. In addition, a systematic review of literature allows for efficient access relevant information from an extended timeframe collated in a single document. There was, therefore, a systematic search for keywords based on reproductive studies with animals in these genera conducted, and 58 articles, 12 books, and three academic theses were subsequently selected. Even though there have been advances in knowledge of the reproductive biology of animals from these genera that have occurred in recent decades, especially research conducted when these NHP were in captivity, a wide variety of areas remain to be studied so that the understanding of reproduction in these NHP can be enhanced and the knowledge gained from these studies utilized for greater understanding of reproduction of NHP in general.