Secretory Phase : The secretory phase of the menstrual cycle extends from 12- 14 days. The production of LH continued in secretory phase in which a yellowish body called the corpus luteum is developed from empty ruptured follicle. Progesterone released by corpus luteum together with estrogen produced by the ovaries, produces changes in the secondary sex organs to prepare the body for pregnancy. Since these changes are due to the progesterone, this phase is also known as progesterone phase or luteal phase. 

Secretory phase is associated with following changes in uterus and ovary.

(1) Changes in uterus : In this phase, thickness of endometrial progressively increases. The arteries of the endometrium become coiled and glycogen content of the endometrial epithelium increases. Towards the end of the secretory phase, the endometrium is thick, soft and richly supplied with .blood. These changes are the obvious preparation for providing a suitable environment for fertilized ovum. The uterine glands become active and are filled with secretions and uterine movements are reduced so that uterus may not contract. However, in the absence of pregnancy, these measures are abortive.

(2) Changes in ovary : In case, the ovum is not fertilized, progesterone level decrease as the corpus luteum undergoes degeneration and the thickened endometrium is shed in the form of a menstrual flow and once again initiating the menstrual cycle.