Female Reproductive System Notes

Female Reproductive System

Functions

• Produce female gametes (oocytes).
• Produce sex steroid hormones (estrogen/progesterone).
• Receive male gametes.
• Allow pregnancy, nourish/develop embryo/fetus.
• Nourish infant via lactation.
• Begins prior to birth.
• Site of fertilization.
• Site of implantation (uterus).
• Allow birth of baby.

Oogenesis

• Production of gametes (oocytes).

Reproductive Organs: Ovaries

• Held in place by:
  • Broad ligament
  • Suspensory ligament
  • Ovarian ligament

Hormone Production

• Estrogen
• Progesterone
• Inhibin
• Relaxin

Number of Oocytes

• At birth: 200,000-2 million
• At puberty: ~40,000
• Oocytes in ovary are seen as follicles: follicular cells + oocyte.

Ovarian Cycle

• Typically 28 days of reproductive cycle.
• Day 1 = 1st day of menstruation

Hormones Involved

• FSH (Follicle Stimulating Hormone)
• LH (Luteinizing Hormone)

Follicular Phase (Day 1-14)

• FSH stimulates the growth of follicles (2mm).

Follicle Development

• Oocyte + Follicular cells = Primordial Follicle
• Zona pellucida formation occurs.
• FSH converts primordial follicle into primary follicle.
• Granulosa cells produce:
  • Estrogen
  • Antral fluid
  • Inhibin
• Dominant follicle will inhibit all other follicles from developing.
• Antrum
• The dominant follicle becomes a secondary follicle.
• Follicles develop at different rates.

Ovulation (Day 14)

• Granulosa cells increase in number.
• Estrogen production increases in follicle.
• Graafian follicle present.
• Normally, low levels of estrogen have (-) feedback on hypothalamus & anterior pituitary.
• High estrogen levels cause (+) feedback on anterior pituitary to cause LH surge.

Graafian/Mature Follicle

• Zona pellucida
• Corona radiata - layer of granulosa cells

LH Surge

• Level of LH increases
• Completes Meiosis I (1° oocyte → 2° oocyte, halted in metaphase II).
• Causes rupture (expulsion) of oocyte = Ovulation (occurs on day 14).
• Ovulation detector kits test for presence of LH (LH surge leads to ovulation).

Mittelschmerz

• Mid-cycle pain during ovulation felt in some females.

Luteal Phase (Day 15-28)

• Only visible for 2 weeks (only if pregnancy occurs).
• 14 days (roughly)
• LH converts ruptured follicular cells into luteal cells
• Granulosa cells form Graafian follicle becomes Corpus hemorrhagicum (bloody).
• Corpus luteum, cholesterol is converted into progesterone, which cells becomes hormone producing factory.

Hormones Produced by Corpus Luteum

• Progesterone (main)

• Estrogen (some)

• Inhibin (prevents FSH)

• Relaxin (relaxes uterus)

• If no fertilization, corpus luteum becomes Corpus Albicans (white) after 2 weeks.

Role of hCG

• If fertilization/implantation occurs, syncytiotrophoblast cells secrete hCG (Human Chorionic Gonadotropin).
• Presence of hCG indicates implantation (pregnancy).