Preantral Follicle Morphometry and Ultrastructure of Antral Follicles in Anatolian Water Buffalo

Abstract

This study aimed to evaluate quantitative and morphometric analyses of preantral follicles and the ultrastructural characteristics of antral follicles in different oestrous cycle stages in Anatolian water buffaloes. Twenty-four ovaries collected from twelve slaughtered Anatolian water buffaloes were classified macroscopically as luteal or follicular stages. The ovaries were prepared for histological examination (Hematoxylin-eosin staining), and primordial, primary, and secondary follicle numbers were calculated, and the diameters of oocytes, follicles, and nuclei were measured under a light microscope with a micrometre. The theca and granulosa cells of antral follicles were observed under a transmission electron microscope. The mean number of preantral follicles was 18584 ± 4855, and there was a significant difference in the number of primordial follicles (p < 0.0001) and primary follicles (p < 0.001) between buffaloes. The number of primordial follicles was 10,636, that of primary follicles was 6514, and that of secondary follicles was 1434; the statistical difference was found between primordial, primary, and secondary follicle and oocyte diameters (p < 0.001) in Anatolian water buffaloes. In this study, the ultrastructural evaluation of antral follicles showed that the theca cells were active in the luteal stage with their functional organelles and higher lipid droplets. The granulosa cells were still inactive in the luteal stage. In the follicular stage of the oestrous cycle, the theca cells were found inactive, although granulosa cells showed moderate or high activity. It was found that the serum progesterone concentration and cycle stage directly affected the theca and granulosa cell ultrastructural activity in Anatolian water buffalo. In this research, information from light and electron microscopic analyses of preantral and antral follicles has been obtained for the first time for Anatolian water buffaloes. The result of our study suggests that detailed molecular research is needed to evaluate the ultrastructural activity of antral follicles in different oestrous cycle stages and steroidogenic circumstances. © TÜBİTAK.