Apoptosis in Postovulatory Follicles of Chalcalburnus Tarichi Pallas, 1811

Abstract

In the present study, apoptosis in postovulatory follicle was investigated with TUNEL staining and agarose gel electrophoresis methods, and plasma 17 beta-estradiol (E2) level was determined at the 1st, 3rd and 5th day after ovulation in Chalcalburnus tarichi. Apoptotic cells were labelled in postovulatory follicles in histological sections on the 1st day after ovulation and it is indicated that apoptosis was observed mainly in granulosa cells and scarcely in theca cells. Oligonucleosomal length DNA fragmentation which is hallmark of apoptosis was observed on the days 1, 3 and 5 after ovulation. While no oligonucleosomal DNA fragmentation was observed on the ovulation time, it was observed that this fragmentation was remarkable on the days 3 and 5. Plasma E-2 level decreased gradually after ovulastion. This decrease was significant on the days 3 and 5 (P<0.05). These results demonstrate that apoptosis is responsible for elimination of postovulatory follicles however it was considered that low level of E-2 after ovulation, accelerates the postovulatory follicle apoptosis in Chalcalburnus tarichi.