Arrange the following events of the menstrual cycle in the correct sequence:
(A) The rising level of FSH stimulates the growth of the ovarian follicle and secretion of estrogen.
(B) The corpus luteum secretes progesterone to maintain the endometrium.
(C) The rapid secretion of LH leads to the rupturing of the Graafian follicle.
(D) The release of unfertilized secondary oocyte leads to the menstrual cycle.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (D), (A), (C), (B)
(D) The release of unfertilized secondary oocyte leads to the menstrual cycle. — first. The cycle starts with the menstrual phase. When the ovum of the last cycle is not fertilised, the endometrium breaks down and menstrual flow occurs for 3-5 days.
(A) The rising level of FSH stimulates the growth of the ovarian follicle and secretion of estrogen. — second. This is the follicular phase. FSH and LH from the pituitary make the primary follicles grow into a Graafian follicle, and the follicle secretes estrogen. The endometrium is built up again.
(C) The rapid secretion of LH leads to the rupturing of the Graafian follicle. — third. LH reaches its peak in the middle of the cycle (about the 14th day). This LH surge breaks the Graafian follicle and releases the ovum. This is ovulation.
(B) The corpus luteum secretes progesterone to maintain the endometrium. — last. This is the luteal phase. The empty follicle becomes the corpus luteum, and its progesterone keeps the endometrium ready for implantation. If there is no fertilisation, the corpus luteum degenerates and a new cycle begins.