APOPTOSIS OCCURS IN GRANULOSA-CELLS BUT NOT CUMULUS CELLS IN THE ATRETIC GRAAFIAN-FOLLICLES IN MULTIPAROUS PIG OVARIES

The process of apoptosis in granulosa and cumulus cells of ovarian fol licles during follicular atresia was investigated in multiparous pigs. In healthy follicles, no apoptotic cells were observed histochemicall y, and no DNA ladder formation or Ca2+/Mg2+-dependent endonuclease act ivity were detected biochemically in granulosa or cumulus cells. In th e follicles in the early stage of atresia, apoptosis occurred in granu losa cells located on the inner surface of the follicular wall but not cumulus cells. DNA ladder formation was observed in granulosa but not cumulus cells, and high levels of endonuclease activity were demonstr ated only in the granulosa cells. No endonuclease activity was detecte d in cumulus cells obtained from the same atretic follicles. These fin dings suggest a lack of apoptotic cell death in cumulus cells in atret ic follicles in multiparous pig ovaries.