Skip to main content
warning

This article is automatically translated and has not been reviewed by an expert yet!

Physiology of the Female Reproductive System

Ovarian Function and Cyclical Changes​

Ovarian Cycle​

  • Definition: The Ovarian Cycle refers to the periodic changes in form and function of the ovaries, occurring from puberty until menopause.
  • Three Phases:
    • Follicular Phase (Proliferative Phase).
    • Ovulation.
    • Luteal Phase.

The corresponding changes in the endometrium are as follows:

  • Menstrual Phase: The period when the endometrium sheds and is expelled through the vagina, typically lasting 3-7 days. During this time, the functional layer of the endometrium sheds due to a decline in hormone levels, resulting in menstrual bleeding.
  • Proliferative Phase: Immediately following the menstrual phase, also known as the follicular phase. As the ovaries secrete estrogen, the endometrium thickens, with cells rapidly dividing and multiplying to prepare for potential fertilized egg implantation. This phase generally starts on day 6 of the menstrual cycle and continues until ovulation.
  • Secretory Phase: This period, from ovulation until the start of the next menstrual cycle, is also called the luteal phase. Here, the corpus luteum secretes progesterone, making the endometrium even thicker and richer in nutrients, providing a suitable environment for fertilized egg implantation and early embryonic development. If fertilization does not occur, the corpus luteum degenerates, progesterone levels drop, and the endometrium begins to degrade, leading into the next menstrual cycle.

Note: Although not directly mirroring each other, the endometrial and ovarian cycles are coordinated. The menstrual and proliferative phases of the endometrium align with the follicular phase of the ovary, while the secretory phase of the endometrium following ovulation corresponds to the luteal phase of the ovary.