Biological Characteristics Of Buffalo Ovarian Follicular Granulosa Cells Apoptosis

Generally, the most of follicles undergo atresia and degeneration during their development in mammals, and only a few of them grow uninterruptedly to maturation until ovulation. The mechanism of the follicle atrisia still remains unclear although many studies on the follicle atresia have been conducted by many researchers. In this study some experiments on follicular atresia were carried out in buffalo as follows:1 , The morphological changes of apoptosis on tissue sections of healthy follicles and atretic follicles in buffalo's ovaries were observed by light microscope and transmit electronic microscope, the apoptosis of the gralulosa cells drew from buffalo ovarian follicle was examined by fluoromicroscope. The result shown that follicular cells have typical changes of apoptosis such as, condensation of chromatin, nucleoplasmic segmentation and congregated under nuclear membrane; cell membrane shrinkage, organelle congregate and were dark-stained under microscope. There were a mass of apoptotic bodies which were enwrapped by integrate membrane in atresic follicular cavity; Apoptotic granulosa cells displayed brighter blue than normal cells under fluoromicroscope.2, The "smear" pattern that reflected DNA break down was not found in healthy follicles and the "smear" was found in atretic follicles by granulosa cells DNA electrophoretic analysis. But the typical "ladder" pattern of granulosa apoptosis was not found in both healthy follicles and atretic follicles.3 , Aoptotic changes of granulosa cells were examined in the healthy and atretic follicles of buffalo's ovaries by TUNEL, the results showed that there are few TUNEL-positive cells in healthy follicles. But there are many TUNEL-positive cells in atretic follicles, namely, lots of DNA fragments from apoptotic cells or necrotic ones can be dyed in black-brown, being positive.4, The Fas protein localization in buffalo's ovary indicated that there were many expressions of Fas gene in granulose cells layer, theca cells layer and base membrance. Immunohistochemical staining for Fas was more intense in granulosa cells compared with theca cells and base membrance cells; moreover, Fas express distinctly higher in atretic follicles than that in healthy follicles.