Progesterone regulates the viability of cells of several different rep
roductive tissues, including the uterus, breast, corpus luteum, and ov
arian follicle (that is, granulosa cells). Progesterone's antiapoptoti
c actions are thought to be mediated through the progesterone receptor
because the progesterone antagonist RU 486 attenuates progesterone's
action. Uterine, mammary, and luteal cells express the classic nuclear
progesterone receptor; whereas granulosa cells of developing and matu
re follicles do not. This review presents data that suggest that proge
sterone maintains granulosa cell viability through a nongenomic mechan
ism. (C) 1997, Elsevier Science Inc.