Efeitos da dexametasona sobre o desenvolvimento, viabilidade e ultraestrutura de folículos secundários bovinos e ovinos cultivados in vitro

Abstract

The aim of this study was to evaluate the effects of different dexamethasone concentrations on development, viability, antrum formation and morphological integrity in in vitro bovine secondary follicles for 18 days. For this purpose, bovine ovaries were obtained from a local slaughterhouse under aseptic conditions already standardized. In the laboratory, secondary follicles approximately 150-200µm in diameter were isolated and intended for in vitro culture in TCM-199 + drops alone or supplemented with different concentrations of dexamethasone (1, 10, 100 and 1000ng / mL). At the end of the cultivation period, the cultured follicles were destined to evaluate the viability with the calcein-AM dyes (viable) and homodimer ethidium (not viable), as well as to evaluate the follicular diameters and antrum formation on days 0, 6, 12 and 18. In addition, before and after in vitro culture, the follicles were fixed for histological and ultrastructural analysis. Follicular growth data were submitted to ANOVA, followed by the T test, while for the analysis of follicular viability and antrum formation, the Chi-square test was used (p <0.05). The follicles cultivated in all dexamethasone treatments showed significant growth, but only those follicles cultivated with 1ng / mL and 1000ng / mL showed growth up to 12 days of cultivation, but there was no significant difference between treatments. Cultivated follicles showed antral cavity formation at the end of the cultivation period. The follicles cultured in the presence of dexamethasone were green (calcein), indicating viability. Morphology and ultrastructure showed that dexamethasone-grown follicles had preserved ultrastructure. However, oocytes from follicles cultured with 10, 100 or 1000ng / mL dexamethasone had signs of degeneration. It can be concluded that in vitro cultured follicles in the presence of dexamethasone showed in vitro growth, as well as maintenance of viability and follicular ultrastructure.