• The removal of inhibin-A and estradiol and increasing GnRH pulses combine to allow greater secretion of FSH compared with LH. • The increase in FSH is instrumental in rescuing approximately a 70- day-old group of ready follicles from atresia, allowing a dominant follicle to begin its emergence.
Follicular Phase • At the start of a menstrual cycle, a cohort of follicles are recruited (rescued) to undergo growth. An increase in FSH is the critical feature in rescuing a cohort of follicles from atresia. • Usually each cohort of follicles that begins growth is engaged in a serious competition that ends with only one follicle succeeding. • The ovulatory follicle is one selected from a cohort recruited at the time of the luteal-follicular transition. • Initial follicular development occurs independently of hormone influence. • FSH stimulation propels follicles to grow to the preantral stage. • FSH-induced aromatization of androgen in the granulosa results in the rising of estrogen levels. • Estrogen stimulates endometrial proliferation.
Ovulation • The LH surge initiates the continuation of meiosis in the
- Winter '16
- Bill Oyieke