Overview
This lecture compares the control and hormonal regulation of gamete production (gametogenesis) in the male and female reproductive systems, highlighting key differences in timing, hormonal cycles, and feedback mechanisms.
Differences in Timing of Gametogenesis
- Female gamete precursor cells are all present at birth, with meiosis resuming at puberty and occurring monthly.
- In males, germ cell mitosis pauses at birth and resumes at puberty, continuing throughout adulthood to produce sperm continuously.
Hormonal Control in Females
- Female gametogenesis is regulated by oscillating levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), resulting in monthly cycles.
- Negative feedback from estrogen and progesterone inhibits FSH and LH during childhood and the luteal phase.
- After menopause, decreased estrogen and progesterone stop negative feedback, causing elevated FSH and LH levels.
Hormonal Control in Males
- Testosterone drives male sexual development and continuous sperm production (spermatogenesis) from puberty throughout adulthood.
- LH from the anterior pituitary stimulates Leydig cells to produce testosterone.
- FSH stimulates Sertoli cells, which support spermatogenesis and secrete inhibin to provide negative feedback.
- Testosterone and inhibin both exert negative feedback on the hypothalamus and pituitary to maintain stable hormone levels.
- Male gametogenesis lacks the monthly cycling present in females; spermatogenesis is constant during adulthood.
Key Terms & Definitions
- Gametogenesis — Process of producing gametes (eggs or sperm) via mitosis and meiosis.
- Spermatogenesis — Formation of sperm cells in males.
- Oogenesis — Formation of egg cells in females.
- Leydig cells — Testicular cells that secrete testosterone in response to LH.
- Sertoli cells — Support cells in testes that regulate spermatogenesis and respond to FSH and testosterone.
- LH (Luteinizing hormone) — Pituitary hormone stimulating sex hormone production.
- FSH (Follicle-stimulating hormone) — Pituitary hormone stimulating gamete development.
- Inhibin — Hormone from Sertoli cells that inhibits FSH secretion.
- Negative feedback — Mechanism to reduce hormone production and maintain balance.
Action Items / Next Steps
- Review diagrams or charts of hormonal control in male and female reproductive systems.
- Prepare for next lecture on the initiation of puberty and hormone secretion triggers.