In the human female, menstruation can be deferred by the administration of:
LH only
Combination of FSH and LH
Combination of estrogen and progesterone
FSH only
Answers
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]