Ovary Changes

• Follicular Phase

  Day 1-14
• Follicular Phase

  The hypothalamus secretes GnRH which stimulates the anterior pituitary gland to release gonadotropin hormone - FSH.
• FSH 


  Hormone that stimulates the ovaries to produce multiple follicles.
• Only one follicle typically matures into a dominant follicle called Graafian follicle, which will release an egg (ovum).
• Estrogen levels rise as the follicles grow, leading to the thickening of the endometrial lining in the uterus, preparing it for potential implantation.
• Follicular Phase

  Hormones:

  • FSH: Stimulates follicle growth.
  • Estrogen: Produced by the growing follicles, promotes endometrial thickening.
• Ovulation Phase

  Day 14
• Ovulation Phase

  The surge of luteinizing hormone, triggered by high estrogen levels, causes the Graafian follicle to release an egg (ovum) from the ovary.
• Ovulation Phase

  • The egg travels into the fallopian tube, where fertilization by sperm may occur.
  • Ovulation lasts only about 24 hours.
• Ovulation Phase

  Hormones:

  • LH Surge: Triggers ovulation.
  • Estrogen: Peaks just before ovulation.
• Ovulation Signs:

  • Mittelschmerz: Sharp, brief pain in the lower abdomen.
  • Cervical mucus becomes thin and stretchy (spinnbarkeit), facilitating sperm motility.
  • A slight increase in basal body temperature (BBT) after ovulation.
• Luteal Phase

  Days 15-28
• Luteal Phase

  After ovulation, the ruptured follicle transforms into the corpus luteum, which secretes progesterone.
• Luteal Phase

  Progesterone prepares and maintains the endometrium (uterine lining) for potential implantation of a fertilized egg.
• Luteal Phase

  If fertilization occurs, the corpus luteum continues to function, supported by human chorionic gonadotropin (hCG) from the developing embryo.
• Luteal Phase

  If fertilization does not occur, the corpus luteum degenerates (corpus albicans), progesterone and estrogen levels drop, leading to endometrial shedding (menstruation).
• Luteal Phase

  Hormones:

  • Progesterone: Dominates this phase, secreted by the corpus luteum to maintain the endometrium.
  • Estrogen: Also remains elevated but secondary to progesterone.
• Summary of Hormonal Control:

  • Follicular Phase: Dominated by FSH and estrogen, preparing the egg and uterine lining.
  • Ovulation: Triggered by an LH surge, with estrogen peaking.
  • Luteal Phase: Dominated by progesterone, maintaining the endometrium for potential implantation.