Question

LH surge occurs during phase of menstrual cycle

• A. Menstrual phase
• B. Beginning of proliferative phase
• C. Just before end of proliferation phase
• D. At the middle of the cycle

Answer 1

The correct option is D At the middle of the cycle

Menstrual cycle
The cyclic changes that occur in the ovaries and the lining of the uterus in the female reproductive system of primates is called menstrual cycle. Examples include humans, monkeys etc.

Phases of menstrual cycle
The menstrual cycle consists of three phases as follows:
1)Menstrual /bleeding phase
2)Follicular or proliferative phase
3)Luteal or secretory phase

Menstrual phase
Menstrual or bleeding phase lasts for about 3 - 5 days.
1)Degeneration of corpus luteum results in the decreasing level of progesterone.
2)There is shedding of the endometrium resulting in discharge of blood, cells etc., from the vagina.

Proliferative phase
Follicular or proliferative phase lasts for about 7 - 8 days.
1)In this phase the follicular cells mature and give rise to the Graffian follicle.
2)Endometrium becomes thicker by rapid cell multiplication, an increase of uterine glands and blood vessels.
3)Rapid secretion of LH leading to its maximum level during the mid cycle induces rupture of the Graffian follicle and thereby the release of the ovum (ovulation).

LH surge
LH surge is rapid secretion of LH caused by the rise of estrogen levels. This happens on the 14th day in the middle of the menstrual cycle or at the end of the follicular or proliferative phase. LH surge induces the rupture of Graffian follicle and the release of the secondary oocyte.


Final answer
(d) At the middle of the cycle