Stem cells have been isolated from ovaries, and their ability to differentiate into oocytes in vitro has been demonstrated for mice and human, but not for bovine species. The aims of this study were to isolate germline stem cells from bovine ovaries and to evaluate the effects of bone morphogenetic proteins (BMPs) 2 and 4, and follicular fluid on the differentiation of these stem cells into oocyte-like structures. The ovarian stem cells were isolated and cultured in α-MEM supplemented with BMP2, BMP4 or follicular fluid. On days 0 and 14, cells were evaluated for their morphological appearance, viability, expression of alkaline phosphatase and for markers of germ cell formation (VASA and DAZL) and oocyte development (GDF9, ZPA and SCP3) by qPCR. Levels of mRNA were analysed using ANOVA and Bonferroni test (p < .05). The results showed that at day 0, ovarian stem cells expressed specific markers of pluripotency (OCT4, SOX). In addition, these cells were positive for alkaline phosphatase, which is a marker commonly used to identify primordial germ cells (PGCs). After the period of differentiation, cells had morphological features that resemble PGCs and oocyte-like cells (OLCs). An increase, ranging from five to 14 times, in the expression of VASA was observed in cells cultured in medium supplemented with BMPs and follicular fluid, while the increase in DAZL expression ranged from four to six times. In addition, OLCs had an increase in expression of mRNAs for GDF9, ZPA and SCP3 that ranged from two to eight times. In conclusion, OLCs can be differentiated in vitro from ovarian stem cells and BMPs and follicular fluid are effective in stimulating the expression of mRNAs for germ cell and oocyte markers.

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The objective this study was to determine the effect of phytohemagglutinin (PHA) on survival, growth and gene expression in caprine secondary follicles cultured in vitro. Secondary follicles (∼0.2 mm) were isolated from the cortex of caprine ovaries and cultured individually for 6 days in α-MEM+ supplemented with PHA (0, 1, 10, 50, 100, or 200 µg/mL). After 6 days of culture, follicle diameter and survival, antrum formation, ultrastructure and expression of mRNA for FSH receptors (FSH-R), proliferating cell nuclear antigen (PCNA), and neuronal nitric oxide synthase were determined. All treatments maintained follicular survival [α-MEM+ (94.59%); 1 µg/mL PHA (96.43%); 10 µg/mL PHA (84.85%); 50 µg/mL PHA (85.29%); 100 µg/mL PHA (88.57%), and 200 µg/mL PHA (87.50)], but the presence of 10 µg/mL PHA in the culture medium increased the antrum formation rate (21.21%) when compared with control (5.41%, P < 0.05) and ensured the maintenance of oocyte and granulosa cell ultrastructures after 6 days of culture. The expression of mRNA for FSH-R (2.7 ± 0.1) and PCNA (4.4 ± 0.2) was also significantly increased in follicles cultured with 10 µg/mL PHA in relation to those cultured in α-MEM+ (1.0 ± 0.1). In conclusion, supplementation of culture medium with 10 µg/mL PHA maintains the follicular viability and ultrastructure, and promotes the formation of antral cavity after 6 days of culture in vitro.

This study aims to investigate the effects of jacalin and follicle-stimulating hormone (FSH) on activation and survival of goat primordial follicles, as well as on gene expression in cultured ovarian tissue. Ovarian fragments were cultured for 6 days in minimum essential medium (MEM) supplemented with jacalin (10, 25, 50 or 100 μg/ml - Experiment 1) or in MEM supplemented with jacalin (50 μg/ml), FSH (50 ng/ml) or both (Experiment 2). Non-cultured and cultured tissues were processed for histological and ultrastructural analysis. Cultured tissues from Experiment 2 were also stored to evaluate the expression of BMP-15, KL (Kit ligand), c-kit, GDF-9 and proliferating cell nuclear antigen (PCNA) by real-time polymerase chain reaction (PCR). The results of Experiment 1 showed that, compared with tissue that was cultured in control medium, the presence of 50 μg/ml of jacalin increased both the percentages of developing follicles and viability. In Experiment 2, after 6 days, higher percentages of normal follicles were observed in tissue cultured in presence of FSH, jacalin or both, but no synergistic interaction between FSH and jacalin was observed. These substances had no significant effect on the levels of mRNA for BMP-15 and KL, but FSH increased significantly the levels of mRNA for PCNA and c-kit. On the other hand, jacalin reduced the levels of mRNA for GDF-9. In conclusion, jacalin and FSH are able to improve primordial follicle activation and survival after 6 days of culture. Furthermore, presence of FSH increases the expression of mRNA for PCNA and c-kit, but jacalin resulted in lower GDF-9 mRNA expression.