Feedback Mechanism The progressive secretion of FSH causes

Feedback Mechanism • The progressive secretion of FSH, causes the estrogen secreted by theka interna and membrana granulosa of follicles to increase progressively. • When the estrogen hormone reaches a specific level in blood, it causes a positive feedback on adenohypophysis, while causing a negative feedback on hypothalamus. • While stimulating LH hormone secretion from the gonadotropic complex, it also prevents FSH-RH secretion from hypothalamus. Thus as FSH secretion decreases; the LH which is secreted in increasing proportions in the gonadotropic complex affects the Graaf folicle and causes ovulation to occur.

Feedback Mechanism • In the concavity formed after the Graaf folicle eruption, a synergy of LH and LTH (prolactin) occurs causing corpus luteum periodicum to form; this new composed structure starts to secrete progesterone. • The secreted progesterone, causes a negative feedback on adenohypophysis while causing a positive feedback on hypothalamus and stopping FSH secretion in gonadotrapic complex, prevents new follicle formation and development. • Because of the progesterone secretion decrease resulting from the luteolysis of corpus luteum periodicum, the negative feedback on adenohypophysis will be removed; resulting in FSH secretion and increase in follicular development.