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In vitro culture of ovarian tissue containing primordial follicles is an important tool to study the initiation of follicular populations and to develop efficient culture systems to support in vitro follicle growth. Considering that in vitro culture favours oxidative stress, it is very important to supplement culture medium with antioxidant substances such as Aloe vera extract. This study aims to evaluate the effects of different concentrations of Aloe vera on the distribution of collagen fibres in the extracellular matrix, follicular activation, development and survival in bovine ovarian cortical tissues cultured in vitro , as well as on expression of mRNAs for antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), peroxiredoxin 6 (PRDX6) and glutathione peroxidase 1 (GPX1)]. To this end, ovarian cortical tissues were cultured for 6 days in α-MEM alone or supplemented with different concentrations of Aloe vera extract (1.0, 5.0, 10.0 or 50.0%). After culture, fragments were fixed and processed histologically to evaluate follicular morphology and activation, as well as the extracellular matrix by staining with picrosirius red. The levels of mRNA for SOD , CAT , PRDX6 and GPX1 in cultured ovarian tissues were evaluated by real-time polymerase chain reaction (PCR). Ovarian tissues cultured with 10.0 or 50.0% Aloe vera had higher percentages of collagen fibres than tissues cultured in control medium. A significant increase in developing follicles was observed in ovarian tissues cultured in α-MEM alone or supplemented with 10% Aloe vera when compared with fresh control or tissues cultured with 1.0% Aloe vera . Presence of Aloe vera did not influence the percentage of morphologically normal follicles when compared with control medium. Ovarian tissues cultured with 50.0% Aloe vera had higher percentages of morphologically normal follicles than those cultured with 10.0% Aloe vera . Furthermore, 10% Aloe vera significantly increased mRNA levels for PRDX6 . In conclusion, 10.0% Aloe vera improves extracellular matrix distribution in cultured tissues and increases the expression of mRNA for PRDX6 after 6 days in vitro .

The aim of this study was to evaluate the effects of different concentrations of BMP4 on activation, development and mRNA expression of GDF9, BMP15, PCNA, Bax and Bcl2 in cultured bovine follicles enclosed in ovarian tissues. Ovarian tissue fragments were cultured for 6 days in α-MEM+ alone or supplemented with different concentrations of BMP4 (10, 50 or 100 ng/ml). Classical histology was performed to analyze follicle growth and morphology, while real-time PCR was used to analyze mRNA levels in fresh and cultured tissues. After 6 days, the culture of ovarian tissue in α-MEM+ alone or supplemented with 10, 50 or 100 ng/ml BMP4 promoted follicular activation. The different concentrations of BMP4 maintained the percentage of normal follicles similar to results of the control. The presence of 100 ng/ml BMP-4 in culture medium increased oocyte and follicular diameters of primary and secondary follicles when compared with those follicles from uncultured control or cultured in α-MEM+ alone (P < 0.05). The tissues cultured in the presence of increasing concentrations of BMP4 had an increase in mRNA expression of the tested genes, but despite this the differences were not statistically significant. In conclusion, 100 ng/ml BMP4 promotes an increase in diameters of follicles and oocytes of primary and secondary follicles after 6 days of in vitro culture.

Oxidative stress during in vitro of ovarian tissues has adverse effects on follicle survival. α-pinene is a monoterpenoid molecule with antioxidant activity that has great potential to maintain cell survival in vitro. This study investigated the effect of α-pinene (1.25, 2.5, 5.0, 10.0, or 20.0 μg/mL) on primordial follicle growth and morphology, as well as on stromal cells and collagen fibers in bovine ovarian slices cultured for six days. The effect of α-pinene on transcripts of catalase (CAT), superoxide dismutase (SOD), peroxiredoxin 6 (PRDX6), glutathione peroxidase (GPX1), and nuclear factor erythroid 2-related factor 2 (NRF2) was investigated by real-time PCR. The tissues were processed for histological analysis to evaluate follicular growth, morphology, stromal cell density, and collagen fibers. The results showed that 2.5, 5.0, or 10.0 µg/mL α-pinene increased the percentages of normal follicles but did not influence follicular growth. The α-pinene (10.0 µg/mL) kept the stromal cell density and collagen levels in cultured bovine ovarian tissue like uncultured tissues. Ovarian tissues cultured in control medium had reduced expression of mRNA for NRF2, SOD, CAT, GPX1, and PRDX6, but α-pinene (10.0 µg/mL) increased mRNA levels for NRF2 and PRDX6. In conclusion, 10.0 µg/mL α-pinene improves the follicular survival, preserves stromal cell density and collagen levels, and increases transcripts of NRF2 and PRDX6 after in vitro culture of bovine ovarian tissue.

Abstract This study aimed to compare the effects of nandrolone decanoate on the morphology and physiology of ovarian tissues in two experimental models, Zebrafish and rats, after in vitro cultivation. A total of 136 animals were used (Wistar rats, n=36, and Zebrafish, n=100). In both experiments, the animals were divided into two groups (Control and Deca) and were exposed to nandrolone decanoate for seven weeks. At the end of the administrations, the animals were euthanized, and the tissues were collected for morphological and biochemical analyses. Data were expressed as mean ± SEM. Tukey and Shapiro-Wilk tests were used. ANOVA and chi-square tests were applied for group comparisons. Differences were considered significant when P<0.05. The results showed an increase in body weight in Wistar rats, while Zebrafish body weight was decreased. In both experiments, the number of atretic follicles increased throughout the in vitro culture, from day 0 to day 7, in the Control group (CTRLr and CTRLz), while in the DECA group (DECAr and DECAz), atretic follicles were reduced from D0 to D7. The antioxidant environment, represented by increased the thiol content, which was significantly higher on day zero in CTRLz compared to CTRLr. SOD activity increased in Zebrafish (group DECAz), while CAT activity decreased in both models (group DECAr and DECAz). In conclusion, the study demonstrated similarity in ovarian physiology between the models exposed or not exposed to nandrolone decanoate, suggesting that, when convenient, researchers could consider changing the experimental model.

This study aimed to evaluate the relationship between antral follicular count (AFC) and ovarian volume (OV), preantral follicular population and survival, meiotic progression and ultrastructure of cumulus–oocyte complexes (COCs) after in vitro maturation. In experiment 1, the relationship between AFC and preantral follicle population and survival was evaluated by classical histology. In experiment 2, the relationship among AFC, OV, ability of oocytes to resume meiosis and ultrastructure of in vitro matured bovine COCs was studied. A positive correlation ( P < 0.05) between AFC and the numbers of healthy primordial, degenerate and total follicles was observed, as well as with healthy secondary follicles and total follicles. The numbers of grades I and II oocytes in ovaries of high AFC class were higher compared with those with intermediate or lower AFC. After in vitro maturation, COCs from ovaries of high AFC had a higher percentage of oocytes in metaphase II compared with those of intermediate and low AFC ( P < 0.0001). Ovaries of intermediate AFC had a higher percentage of oocytes in metaphase II compared with ovaries with low AFC ( P < 0.0001). The proportion of oocytes in metaphase I, telophase I and anaphase I in COCs from ovaries of intermediate AFC (26.04%) was higher ( P < 0.05) compared with that seen in COCs of ovaries with high (8.55%) and low (14.15%) AFC. No differences in the ultrastructure of oocytes were seen. In conclusion, after in vitro maturation, cow ovaries with high AFC have higher numbers of oocytes that reach in metaphase II (MII), but they also have higher numbers of degenerated primordial and primary follicles.