Mention the importance of LH surge during menstrual cycle.

Explanation

Rapid secretion of LH leading to its maximum level during the mid menstrual cycle (14th day) called LH surge induces rupture of Graafian follicle and thereby the release of ovum (ovulation).
The ovulation (ovlatory phase) is followed by the luteal phase during which the remaining parts of the Graafian follicle transform as the the corpus luteum. The corpus luteum secretes large amounts of progesterone which is essential for maintenance of the endometrium. Such an endometrium is necessary of implantation of the fertilised ovum and other events of pregnancy.