The secretion of gonadotropins, i.e., LH and FSH increase gradually during the follicular phase, which stimulate follicular development as well as secretion of estrogens by the growing follicles. The rapid secretion of LH during mid-cycle induces rupture of Graafian follicle and thereby release of ovum. The corpus luteum, developed from Graafian follicle, secretes large amounts of progesterone which is essential for maintenance of endometrium for implantation.
