Male Reproductive System

Male Reproductive System Overview

• Focus on the testis as a primary reproductive organ.
• Testis functions as a manufacturing complex producing sperm, hormones, and proteins.

Testicular Structure

• Testis divided into two main compartments:
  • Tubular compartment: where sperm production occurs.
  • Interstitial compartment: contains Leydig cells (hormone production).

Sperm Production

• Occurs in seminiferous tubules.
• Germ cells at various maturation stages, with immature cells near the basement membrane.
• Sertoli cells (nurse cells) play essential roles in sperm development and support.

Sertoli Cell Functions

• Facilitate sperm maturation and production through:
  • Phagocytosis of damaged sperm.
  • Maintenance of spermatogonial stem cells and their niche.
  • Endocrine signaling response and regulation.
• Express FSH receptors, which stimulate their functions.

Hormonal Regulation

• FSH (Follicle Stimulating Hormone): primary driver of Sertoli cell function.
• LH (Luteinizing Hormone): acts on Leydig cells for androgen production.
• Inhibin: produced by Sertoli cells to suppress FSH levels in a feedback mechanism.

Spermatogenesis Process

• Spermatogonia renew throughout male lifespan post-puberty.
• Endocrine signaling (FSH, LH) governs spermatogenesis and testosterone production.

Key Molecules Produced by Sertoli Cells

• Growth factors: FGF, EGF, PDGF, GDNF (essential for germ cell development).
• Androgen binding protein: maintains local levels of androgens (from Leydig cells).
• Transferrin: iron transport.
• Chemokines: ensure retention of spermatogonial stem cells.

Blood-Testis Barrier

• Formed by tight junctions between Sertoli cells, preventing immune cell access to developing sperm.
• Disruption leads to impaired sperm production.

Conclusion

• Sertoli cells essential for male fertility, supporting sperm maturation via multiple hormonal pathways and functions.