(i) Follicular phase: Follicular phase is also called the proliferative phase. During the phase, the FSH released by the pituitary stimulates the growth of the primary ovarian follicles and also causes maturation of the primary oocyte in this follicle, The follicular cells of the Graafian follicle secrete estrogen growth of the primary ovarian follicles and also causes maturation of the primary oocyte in this follicle. The follicular cells of the Graafian follicle secrete estrogen. Due to an increased level of estrogen the uterine endometrium becomes thick, more vascular and more glandular. This phase lasts for about 10 to 14 days, or until ovulation occurs.
(ii) Luteal phase: Development of corpus luteum, secretion of progesterone.
