• 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.
Feedback Mechanism
