Question

What happens to levels of FSH (follicle-stimulating hormone) if ovulation does not occur? How does it affect menstruation and the levels of estrogen & progesterone?

Answer 1

1) The FSH level will be increased.

FSH or follicle-stimulating hormone is released from the anterior pituitary gland for the development of the follicle in the ovary. When ovulation occurs means secondary oocyte comes out from the follicle due to the high level of LH hormone, and the FSH level is decreased because after ovulation follicle change into the corpus luteum. So for corpus luteum, we don't need FSH. But if ovulation does not occur, the follicle will not change into the corpus luteum. For the presence of follicle, our pituitary gland will continue FSH's secretion so its level will rise.

2) Due to FSH, the ovarian follicle is matured and produces estrogen hormone. As I already told that after ovulation, the follicle changes into the corpus luteum which produces progesterone in high amount and also produces estrogen but in a low amount. If ovulation does not occur, FSH will continuously work on the follicle and stimulate it for estrogen production so estrogen level will be high. And because there is no ovulation, the follicle will not change into corpus luteum so progesterone will not be produced ( because progesterone is secreted from the corpus luteum) so the level of the progesterone will be decreased.

The menstruation will stop if ovulation does not occur. There will be no menstrual bleeding.

When the ovary is preparing for ovulation, the uterus is also prepared by the estrogen ( produced by the follicle). Estrogen makes the endometrium wall of the uterus thicker and more vascularized so that after ovulation if the oocyte is fertilized, it can get proper environment for implantation. When ovulation occurs, if the egg is fertilized by any sperm, the egg goes to the endometrium, and implantation occurs and if not fertilized, the egg comes out   with the break down of the endometrium layer of the uterus and blood which is known as menstrual bleeding. The endometrium wall is broken down due to the low level of estrogen and as well as for the low level of progesterone because when implantation does not happen progesterone levels also go down.

But if ovulation does not occur, estrogen level will remain high and due to the high level of estrogen, endometrium wall will not be broken so there will be no bleeding. And the process after ovulation where follicle changes into the corpus luteum will stop.