What are the 3 main phases in the menstrual cycle?

1 Answer
Jan 20, 2018

In fact, there are 4 phases of human female menstrual cycle which happens one after another but as you have mentioned #3# main so I will go with:

  • Follicular phase or proliferative phase
  • Luteal or secretory phase
  • Menstrual phase

(One being skipped i.e ovulation phase)

Explanation:

https://www.britannica.com/science/menstruation

Follicular Phase or Proliferative phase:

  • Anterior lobe of pituitary gland releases #FSH#(follicle stimulating hormone) at the start of puberty.
  • This hormone stimulates the development of several primary follicles.
  • Only one of these follicles continue to grow with its primary oocyte.
  • The remaining follicles break down by degenerative process called follicle atresia.

  • FSH stimulates the ovary to produce estrogen hormone.

  • Estrogen stimulates the endometrium(tissue lining inner wall of uterus) and vascularizes it.

  • High level of estrogen inhibits the secretion of FSH from pituitary gland.

{Decrease of FSH and increase of estrogen stimulates the pituitary gland to secrete luteinising hormone#(LH)# which induces ovulation i.e discharge of ovum from follicle. This is known as ovulation phase. Mentioned it! Because otherwise it would be bit tricky to understand the topic}

Luteal phase or Secretory Phase:

  • The follicle cells ruptured in follicle atresia form a special structure called corpus luteum. It is a yellowish grandular structure.
  • Corpus luteum starts secreting progesterone.
  • Progesterone further develops the endometrium and make it receptive for the implantation of zygote. Now if the fertilization occurs then the implantation of zygote take place . And if it does not occur then last phase of female reproductive cycle starts i.e mensturation.

Menstural Phase:

  • In this phase, corpus luteum starts degenerating and thus secretion if progesterone is also reduced.

  • Now endometrium has no supporting effect of progesterone. Consequently endometrium starts to breakdown.

  • This starts the discharge of cell debris and blood through vagina which is known as menstruation.

Hope it helps...