Physiology, Menstrual Cycle
First published: 2024
Brief summary
Clinical reference on menstrual-cycle physiology, ovarian/endometrial phases and hormonal feedback.
Article
The menstrual cycle is regulated through interactions among the hypothalamus, anterior pituitary gland, ovaries and uterus. Its physiological function is to support the maturation and release of an oocyte while preparing the reproductive tract and endometrium for possible fertilisation and implantation.
During the follicular phase, gonadotropin-releasing hormone stimulates pituitary secretion of follicle-stimulating hormone and luteinising hormone. Developing ovarian follicles produce oestrogen, which promotes proliferation of the endometrium and contributes to the hormonal feedback that precedes ovulation.
A sustained rise in oestrogen changes the feedback response and produces the mid-cycle luteinising-hormone surge that triggers ovulation. The ruptured follicle then becomes the corpus luteum, which secretes progesterone and oestrogen during the luteal phase and supports secretory changes in the endometrium.
When implantation does not occur, corpus-luteum function declines and ovarian steroid concentrations fall. The functional layer of the endometrium is shed as menstruation, gonadotropin suppression is reduced, and a new cycle begins with recruitment of another group of ovarian follicles.
Source details and credits
- Source / publisher: NCBI Bookshelf / StatPearls
- Source type: Clinical reference
- URL type: WWW
- Credits: NCBI Bookshelf / StatPearls
- URL: https://www.ncbi.nlm.nih.gov/books/NBK500020/