Overview
This lecture covers the structure and function of the female reproductive system, focusing on the ovaries, hormonal regulation, oogenesis, and the anatomy and function of associated organs.
Ovaries & Gamete Production
- Ovaries produce female gametes (secondary oocytes/egg cells/ova) and secrete estrogen and progesterone.
- Ovaries are held in place by ligaments and have an outer cortex (follicles and germinal epithelium) and inner medulla (connective tissue, blood vessels, nerves).
- All primary oocytes are formed before birth; a female is born with all the eggs she will ever have (about 1 million at birth, 400,000 by puberty).
- Only about 500 oocytes are released over a woman's reproductive lifetime.
Hormonal Regulation
- At puberty, the hypothalamus releases GnRH, stimulating the anterior pituitary to release FSH and LH.
- LH triggers ovulation and the production of sex hormones (estrogen, progesterone).
- FSH stimulates oogenesis (egg formation) in females (spermatogenesis in males).
Oogenesis & Follicle Development
- Oogenesis is the process that forms eggs; primary oocytes are present before birth.
- During each cycle, a primary oocyte matures and, at ovulation, is released as a secondary oocyte (not a mature ovum).
- The corpus luteum forms after ovulation; it secretes progesterone to prepare for pregnancy.
- If pregnancy does not occur, the corpus luteum degenerates into corpus albicans (scar tissue).
Ovulation and Fertilization
- Ovulation releases a secondary oocyte, which is picked up by the fimbriae of the uterine (fallopian) tube.
- Fertilization occurs in the fallopian tube; if implantation occurs here (ectopic pregnancy), it is life-threatening.
- After fertilization, the egg's membrane becomes impermeable to other sperm to maintain correct chromosome number.
Female Reproductive Anatomy
- Uterine tubes (fallopian tubes) transport the secondary oocyte via cilia and peristalsis; site of fertilization.
- Uterus is a muscular, hollow organ with the cervix (neck/outlet), endometrium (shed in menstruation), and myometrium (muscular layer).
- Several ligaments support the uterus and ovaries: broad, round, ovarian, and suspensory ligaments.
- Vagina is a muscular tube from the cervix to exterior; receives semen, is the birth canal, and exit for menstrual blood.
Key Terms & Definitions
- Ovary — Organ producing eggs (oocytes) and female sex hormones.
- Oogenesis — Formation of female gametes (egg cells).
- Corpus luteum (CL) — Structure formed after ovulation; secretes progesterone.
- Corpus albicans — Scar tissue resulting from the degeneration of the corpus luteum.
- Follicle-stimulating hormone (FSH) — Hormone stimulating oocyte and sperm development.
- Luteinizing hormone (LH) — Hormone causing ovulation and hormone production.
- Secondary oocyte — The cell released at ovulation (not a true ovum).
- Fimbriae — Fingerlike projections that guide the oocyte into the uterine tube.
- Endometrium — Uterine lining shed during menstruation.
Action Items / Next Steps
- Review oogenesis and ovarian histology in lab.
- Answer worksheet questions on oogenesis and hormonal regulation.
- Highlight that ovulation releases a secondary oocyte (not a mature ovum) for final exam preparation.