Follicular or Proliferative Phase follows the Menstrual phase and lasts for about 10-12 days (from 5 th to 14 th days of the menstrual cycle). Ovulatory phase involves the ovulation from the Graafian follicle of ovary. It occurs midway between two menstrual cycles (on 15 th day of onset of menstruation). Luteal/Secretory/Post ovulatory phase lasts for about 12-14 days (from $16^{\text {th }}-28^{\text {th }}$ days of menstrual cycle). Corpus luteum is formed from empty Graafian follicle which increases in size. The follicular cells are converted to Lutein cells by deposition of yellowish lipid inclusions, giving it a yellow colour. This phase is the Luteal phase.
Related Theory
Both LH and FSH attain a peak level in the middle of cycle (about 14 $14^{\text {th }}$ day). Rapid secretion of LH leading to its maximum level during the mid-cycle called LH surge induce rupture of Graafian follicle and thereby release of ovum (ovulation).