Role of estradiol in regulating ovarian follicular atresia in rhesus monkeys: a review

The present studies show that estradiol-17B (E2) implanted s.c. in rhesus monkeys for 24 hours reliably induces atresia of the dominant follicle (DF). Analysis of contents of the atretic DF revealed a reduction in cell viability and levels of steroids. These atretogenic effects of E2 could be mimicked by local application, but were not reversed by exogenous gonadotropins. E2 also had a direct effect on inhibiting steroid secretion by follicle cells in vitro. From these studies, we concluded that the effect of E2 is exerted at least in part at the ovarian level; this suggests that estrogen produced locally by the DF could have a physiologic role in controlling atresia of other follicles.