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.