Lecture Notes: Testes and Sperm Production

Overview of Testes

• Two testes, each approximately:
  • Length: 4 cm
  • Width: 2.5 cm
  • Weight: 10-12 grams each
• Main functions:
  • Sperm production
  • Androgen production (e.g., testosterone)

Anatomy of the Testes

• Spermatic Cord

  • Extends from the testes to the abdomen
  • Contains several anatomical structures:
    • Ductus Deferens (Vas Deferens): Carries sperm from the testes to the male reproductive tract
    • Testicular Artery: Branch of the abdominal aorta supplying blood to the testes
    • Pampiniform Plexus: Venous plexus cooling arterial blood for optimal sperm production
    • Testicular Nerve
    • Cremaster Muscle: Raises and lowers the testes for temperature regulation

• Surrounding Muscle Layers

  • Dartos Muscle: Contracts and wrinkles the scrotum for temperature regulation

Temperature Regulation

• Cremaster Muscle: Raises and lowers testes
• Dartos Muscle: Wrinkling of the scrotum
• Testes are outside the body to maintain optimal temperature (2-3°C cooler than body temperature)

Sperm Production

• Epididymis: Storage and maturation site for sperm
• Seminiferous Tubules: Site of sperm production, around 200-250 lobules per testis
• Sperm travels from seminiferous tubules to epididymis, then to ductus deferens

Cellular Anatomy of Seminiferous Tubules

• Sustentacular (Sertoli) Cells: Produce Androgen Binding Protein (ABP)
• Interstitial (Leydig) Cells: Produce testosterone
• Spermatogonia (Sperm Stem Cells): Develop into sperm

Hormonal Regulation of Sperm Production

• Hypothalamus releases Gonadotropin-Releasing Hormone (GnRH)
• Anterior Pituitary Gland: Releases Gonadotropins:
  • Follicle Stimulating Hormone (FSH): Stimulates Sertoli cells to release ABP
  • Luteinizing Hormone (LH): Stimulates Leydig cells to release testosterone
• ABP and testosterone stimulate spermatogenesis

Summary

• FSH stimulates Sertoli cells to produce ABP
• LH stimulates Leydig cells to produce testosterone
• ABP and testosterone work together to initiate spermatogenesis

Contact Information

• For questions or clarifications, email the lecturer.

This document summarizes the key points of the lecture on testes and sperm production, providing a comprehensive overview of the anatomical structures, physiological processes, and hormonal regulation involved in the production of sperm.