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Understanding the Female Reproductive Cycle

May 4, 2025

Overview of the Female Reproductive Cycle

Introduction

  • Dr. Mike provides an overview of the female reproductive cycle.
  • Focus on ovarian and uterine cycles.
  • Discusses hormonal changes associated with these cycles.

Two Major Cycles

  1. Ovarian Cycle
    • Occurs in the ovaries.
    • Involves the development and release of egg cells (oocytes).
  2. Endometrial Cycle (Uterine Cycle)
    • Occurs in the uterus.
    • Prepares the uterus for implantation.

Duration of the Cycle

  • Average cycle duration: 0 to 28 days.
  • Can vary from 25 to 34 days.

Ovarian Cycle

Phases

  1. Follicular Phase (Day 0-14)

    • Primordial Follicle: Contains a primary oocyte surrounded by pregranulosa cells.
    • Primary Follicle: Develops granules and zona pellucida for protection.
    • Secondary Follicle: Granulosa cells multiply, theca cells appear.
    • Graafian (Mature) Follicle: Ovulates around day 14.
    • Hormones involved:
      • FSH (Follicle Stimulating Hormone): Essential for follicle maturation.
      • LH (Luteinizing Hormone): Surges to trigger ovulation.
  2. Luteal Phase (Day 14-28)

    • Corpus Luteum: Forms post-ovulation, produces progesterone.
    • Estrogen produced by granulosa and theca cells regulates feedback to the hypothalamus.

Endometrial Cycle

Phases

  1. Menstrual Phase (Day 0-5):

    • Bleeding occurs, uterine lining sheds due to low hormone levels.
  2. Proliferative Phase (Day 5-14):

    • Uterine lining thickens under the influence of estrogen.
  3. Secretory Phase (Day 14-28):

    • Enhanced by progesterone; development of glands, secretion of enzymes, and mucus production.

Hormonal Regulation

  • Estrogen: Rises, then triggers FSH and LH inhibition; high levels cause a surge in LH leading to ovulation.
  • Progesterone: Increases during the luteal phase, maintaining the endometrium for potential implantation.

Implantation and Hormonal Feedback

  • If implantation occurs, human chorionic gonadotropin (hCG) is secreted, maintaining the corpus luteum.
  • If no implantation occurs, progesterone levels fall, leading to menstruation.

Key Points

  • Estrogen and progesterone play crucial roles in regulating the cycles.
  • Day 14 marks ovulation, key hormonal shifts occur here.
  • The cycle resets if no fertilization occurs.

Conclusion

  • Understanding these cycles is crucial for reproductive health.
  • Dr. Mike encourages further engagement on social media for more insights.