Overview of the Female Reproductive Cycle

Oct 7, 2024

Female Reproductive Cycle Overview

Introduction

  • Discussing the interconnection of the auditory cycle and menstrual cycle.
  • Focus on how these two cycles are intertwined.

Hormonal Pathway

  • Hypothalamus:
    • Contains two nuclei:
      • Pre-optic nucleus (red)
      • Arcuate nucleus (orange)
    • Secretes Gonadotropin-Releasing Hormone (GnRH).

Anterior Pituitary

  • GnRH stimulates the anterior pituitary to release:
    • FSH (Follicle Stimulating Hormone)
    • LH (Luteinizing Hormone)

Ovarian Development

  • At birth, females possess oogonia (diploid stem cells).
  • Oogonia convert into primordial follicles (still diploid) during childhood (pre-puberty).
  • At puberty, localized androgens stimulate primordial follicles to convert into primary follicles.
  • **Primary follicle: **
    • Contains a primary oocyte frozen in prophase I of meiosis.

Follicular Phase (Days 1-14)

  • FSH is critical for the development of follicles:
    • Stimulates proliferation of granulosa cells, forming multiple layers.
    • Stimulates the production of zona pellucida (glycoprotein layer).
    • Granulosa cells produce estrogen.

Progression of Follicles

  1. Primary Follicle ➔ Early Secondary Follicle:
    • FSH stimulates proliferation and estrogen production.
  2. Early Secondary Follicle ➔ Late Secondary Follicle:
    • More layers of granulosa cells and fluid pockets form.
  3. Late Secondary Follicle ➔ Graafian (Tertiary) Follicle:
    • Contains a secondary oocyte frozen in metaphase II of meiosis.
    • Formation of an antrum (large fluid-filled cavity).

Luteal Phase (Days 15-28)

  • Following ovulation, the graafian follicle becomes the corpus luteum:
    • LH stimulates the corpus luteum to produce progesterone and maintain the uterine lining.
    • Inhibin B released by the graafian follicle inhibits FSH production.

Ovulation

  • Triggered by an LH surge, resulting in:
    • Release of the ovum into the fallopian tube.
    • The fimbriae of the fallopian tubes aid in capturing the ovum.

Key Hormones and Their Functions

  • FSH:
    • Stimulates follicle growth and estrogen production.
  • LH:
    • Triggers ovulation and formation of corpus luteum.
  • Estrogen:
    • Regulates menstrual cycle and promotes secondary sexual characteristics.
  • Progesterone:
    • Prepares the uterus for potential implantation of an embryo.

Conclusion

  • The video will continue with an overview of the menstrual cycle and the effects of estrogen and progesterone on the uterus.