The ovarian cycle is initiated by :
FSH Initiated by the release of FSH (From Anterior pituitary) FSH stimulates the Growth of Multiple Follicles (Folliculogenesis) Selection of a dominant Follicle (Graffian Follicle), by day 5-7. Graffian Follicle acquires FSH receptors on Granulosa cells and LH receptors on Theca cell. Under the influence of FSH, Graffian follicle secretes 178 estradiol (Day 7) 178 estradiol causes 4, i 4, Proliferative changes Negative feedback on FSH Positive feedback on LH therefore in the endometrium LH increases in amount. Decreased Amount of FSH Increased LH leads to : Production of androgen from Theca cells which is conveed peripherally to estrogen therefore Estrogen peak occurs (48 hours before ovulation) LH surge (32-36 hours before ovulation) & LH peak (10-16 hours before ovulation) 1 Ovulation Occurs (14 days prior to next cycle) Formation of corpus luteum & 2nd phase of ovulatory cycle i.e. Luteal Phase begins. Secretes Progesterone Stimulates Endometrium to undergo secretory changes 1. In absence of Feilisation corpus luteum degenerates Oestradiol Progesterone Inhibin (inhibin FSH production) (Leads to menstruation in menstrual cycle) & will release the negative Increased FSH as feedback on GnRH, therefore compared to LH increases GnRH pulses L Another follicular phase begins
FSH
Oestrogen
LH
Progesterone