Question

Give an account of the secretory phase of menstrual cycle.

Answer 1

The menstrual cycle is the rhythmic reproductive cycle that divided into the four phases such as menstrual phase, follicular phase, ovulation phase and the luteal phase. The secretory phase of the menstrual cycle extends from 12-14 days. LH stimulation complete the development of the Graafian follicle into a structure the corpus luteum. Progesterone is then release by corpus luteum and 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. Secretory phase is associated with following changes in uterus and ovary:
(1) Changes in Uterus: In secretory phase, thickness of endometrium 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 aborted.
(2) Changes in Ovary : If ovum is not fertilized, progesterone levels decrease as the corpus luteum undergoes degeneration and the thickened endometrium sheds in the form of a menstrual flow and once again initiating the menstrual cycle.