Updated by: Arabinda Naik
Female attains puberty at about the age of 13 years. Currently GnRH (Gonadotropin releasing hormone) is secreted by the hypothalamus which stimulates the anterior lobe of pituitary gland to secrete luteinizing hormone LH and follicle stimulating hormone FSH.
Follicular Stimulating Hormone (FSH):
Follicular Stimulating Hormone (FSH) stimulates the growth of the ovarian follicle and increases young primary oocytes into Graafian follicles. Ripening of the follicles then results in an increase in estrogen levels, as estrogens are secreted by follicular cells. This hormone is responsible for the development of female secondary sexual characters. This increase in estrogen levels feeds back to the pituitary and suppresses further release of FSH (negative feedback). The follicles also release a second hormone called inhibin, which also suppresses further production of FHS.
LH: Luteinizing hormone controls the ovulation process, formation of corpus luteum from Graafian follicle and secretion of progesterone from corpus luteum. The sharp increase in the level of LH also causes rupture of the wall of the Graafian follicles and the secondary oocyte present in the Graafian follicle is released from the ovary. This looks yellow, due to its pigmented lutein cells (luteus is latin for yellow). Corpus lutein secretes progesterone, estrogen, and relaxin. The progesterone levels feed back to the pituitary and suppress further release of LH. If fertilization does not occur, the corpus luteum degenerates into a small white fibrous scar called the corpus albicans. The resulting decline in progesterone (and estrogens) levels precipitate menstruation. The decline in estrogen levels feeds back to the pituitary and there is a corresponding increase in FSH to begin the cycle all over again.