Developmental expression of Ca++/Mg++-dependent endonuclease activity in rat granulosa and luteal cells

A Ca++/Mg++-sensitive endonuclease has been associated with programmed cell death in a variety of endocrine and non-endocrine dependent tissues. In view of the remarkable similarity of the process of the regression of the corpus luteum and other models of programmed cell death, we studied the occurrance of this endonuclease activity in granulosa cells at different developmental states and the corpus luteum. Our results show that while undifferentiated granulosa cells do not express this endonuclease activity, treatment with pregnant mares serum gonadotropin results in a rapid increase in endonuclease activity that is maintained following ovulation and luteinization of granulosa cells.