What is the physiology of a menstrual cycle in a normally functioning ovary?

Updated: Dec 20, 2018
  • Author: Shannon M Grabosch, MD; Chief Editor: Nicole W Karjane, MD  more...
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Answer

The median menstrual cycle lasts 28 days, beginning with the first day of menstrual bleeding and ending just before the subsequent menstrual period. The variable first half of this cycle is termed the follicular phase and is characterized by increasing follicle-stimulating hormone (FSH) production, leading to the selection of a dominant follicle that is primed for release from the ovary. [10]

In a normally functioning ovary, simultaneous estrogen production from the dominant follicle leads to a surge of luteinizing hormone (LH), resulting in ovulation and the release of the dominant follicle from the ovary and commencing the luteinizing phase of ovulation.

After ovulation, the follicular remnants form a corpus luteum, which produces progesterone. This, in turn, supports the released ovum and inhibits FSH and LH production. As luteal degeneration occurs in the absence of pregnancy, the progesterone levels decline, while the FSH and LH levels begin to rise before the onset of the next menstrual period.


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