Follicular atresia is
Degeneration of ovarian follicles
Atresia is a hormonally controlled apoptotic process. Ovarian follicular atresia is the periodic process in which immature ovarian follicles degenerate and are subsequently re-absorbed during the follicular phase of the menstrual cycle. Typically around 20 follicles mature each month but only a single follicle is ovulated. The rest undergo atresia. That single dominant follicle becomes corpus luteum following ovulation.