Answers

Vikas
Jul 28, 2020

Menstrual cycle in human female is under hormonal control in the following ways:
(i) Follicular or proliferative phase is under the influence of FSH from the anterior pituitary.
(ii) The follicular cells of mature follicle secrete oestrogens, which control the growth and maintenance of the secondary sex organs like uterus, Fallopian tube, etc.
(iii) FSH and LH reach their peak level around the mid-cycle (14th day). The peak level of LH surge causes the rupture of Graafian follicle and release of ovum  (ovulation).
(iv) LH influences the remaining parts of Graafian follicle to transform into corpus luteum.
(v) Corpus luteum secretes large quantity of progesterone in the luteal phase. Progesterone is required for the growth and maintenance of endometrium of uterus for implantation.
(vi) In the absence of fertilisation, the high levels of progesterone exert negative feed back on the pituitary. This stops the secretion of LH and corpus luteum  degenerates leading to menstruation