describe the phases of menstrual cycle with respect to changes in ovary and endomatrium.

The menstrual cycle is the reproductive cycle in a human female after puberty. The ovary releases one egg every month. The uterus also prepares itself every month to receive a fertilized egg. The inner uterus lining becomes thick and is supplied with blood to nourish the embryo. The cycle starts with the menstrual flow (3 to 5 days), caused due to the breakdown of the endometrium of the uterus. Blood vessels in liquid state are discharged, but this occurs only when the ovum is not fertilised.

It is followed by the follicular phase.In this phase, the primary follicles mature into the Graffian follicles. This causes the regeneration of the endometrium.

These changes are brought about by ovarian and pituitary hormones. In this phase, the release of gonadotropins (LH and FSH) increases. This causes follicular growth and the growing follicles produce oestrogen.

The LH and FSH are at their peak in the middle of the cycle (14th day), and cause the rupture of the Graffian follicles to release ovum. This phase is called the ovulatory phase.
The remains of the Graffian follicles get converted into the corpus luteum, which secretes progesterone for the maintenance of the endometrium.
In the absence of fertilisation, the corpus luteum degenerates, thereby causing the disintegration of the endometrium and the start of a new cycle.