Histomorphological and histochemical features of atresia of antral follicles of water buffaloes

Abstract

The present study aimed to characterize the atresia of antral follicles of buffalo. Two types of atresia, cystic and obliterative, were observed in the buffalo ovary. The cystic atresia was characterized by complete degeneration of the granulosa cells with the antrum filled with fluid. In obliterative atresia, the granulosa cells degenerated, and the surrounding theca cells started invaginating into the antrum. The ingrowth of these connective tissues filled the antrum. The histological picture of tertiary follicles showed that the atresia occurred in successive stages. The atretic changes observed were pyknosis of granulosa cells, the creation of small spaces between the cells, and the loosening of the cumulus oophorus cells. Two patterns were observed based on the start of atresia, i.e. antral atresia and basal atresia. At places, call-exner bodies were observed in the granulosa cell layer. The collagen fiber-containing basal lamina started separating from the theca layer at locations and later became hypertrophied in the cystic atresia type. In contrast, in the obliterative atresia, the collagen fibers were seen as abundant in growth towards the lumen and later, it filled the whole antral cavity. Disruptions of reticular fibers as stained with Gridley’s stain were observed in the cystic type of atresia, and ingrowth of reticular fibers in the antrum and formation of corpus atreticum were contributed by reticular fibers also.