Question

Withdrawl of which of the following hormones
is the immediate cause of menstruation ?
(a) FSH-RH (b) Progesterone
(c) Estrogen (d) FSH

Answer 1

ANSWER

After ovulation, the pituitary hormones FSH and LH cause the remaining parts of the dominant follicle to transform into the corpus luteum, which produces progesterone. The increased progesterone in the adrenals starts to induce the production of estrogen. The hormones produced by the corpus luteum also suppress production of the FSH and LH that the corpus luteum needs to maintain itself. Consequently, the level of FSH and LH fall quickly over time, and the corpus luteum subsequently atrophies. Falling levels of progesterone trigger menstruation and the beginning of the next cycle

Answer 2

Answer:

The follicular phase of the female menstrual cycle includes the maturation of ovarian follicles to prepare one of them for release during ovulation. During the same period, there are concurrent changes in the endometrium, which is why the follicular phase is also known as the proliferative phase.

Issues of Concern

Follicular Phase

The duration of the menstrual cycle varies and occurs every 21 to 35 days, with an average span of 28 days. Oligomenorrhea describes infrequent menstrual periods and cycles lasting more than 35 days. Polymenorrhea refers to frequent menstrual periods and cycles lasting less than 21 days. It is important to note that the duration of the follicular phase can differ depending on the length of the cycle, while the luteal phase is usually stable and lasts 14 days. Based on a 28-day cycle, the follicular phase measures from the first day of menstruation (day 0) until the beginning of ovulation (day 14). When the previous menstrual cycle completes, and the corpus luteum breaks down, the levels of estrogen, progesterone, and inhibin A will decrease. This chain of events will cause positive feedback to the hypothalamus and anterior pituitary, and a subsequent pulsatile release of GnRH and FSH into circulation. This increase in FSH will stimulate the granulosa cells of the ovaries to recruit several follicles from each ovary. These follicles will complete maturation, and only one Graafian follicle will go through ovulation during that cycle. The increase in FSH also stimulates the secretion of Inhibin B by the granulosa cells. Inhibin B will eventually blunt the secretion of FSH toward the end of the follicular phase. Inhibin B levels will be highest during the LH surge before ovulation, and will quickly taper off after.[1][2]