REGULATION OF OVARIAN FOLLICLE ATRESIA

The majority of ovarian follicles undergo atresia, a hormonally contro lled apoptotic process. Monitoring apoptotic DNA fragmentation provide s a quantitative and sensitive endpoint to study the hormonal regulati on of atresia in ovarian follicles. During follicle development, gonad otropins, together with local ovarian growth factors (IGF-I, EGF/TGF-a lpha, basic FGF) and cytokine (interleukin-1 beta), as well as estroge ns, activate different intracellular pathways to rescue follicles from apoptotic demise. In contrast, TNF-alpha, Fas ligand, presumably acti ng through receptors with a death domain, and androgens are atretogeni c factors. These diverse hormonal signals probably converge on selecti ve intracellular pathways (including genes of the bcl-2 and ICE famili es) to regulate apoptosis. With a constant loss of follicles from the original stockpile, the ovary provides a unique model for studying the hormonal regulation of apoptosis.