Spermatogenesis and Hormonal Regulation

Overview of Spermatogenesis

• Process of sperm formation, occurs in seminiferous tubules.
• Immune privileged site, primarily contains Sertoli and germ cells.

Key Stages of Spermatogenesis

• Proliferation Phase

  • Spermatogonia undergo mitosis to form primary spermatocytes.

• Meiosis Phase

  • Two rounds of meiosis transform primary into secondary spermatocytes, then into spermatids.

• Differentiation Stage (Spermiogenesis)

  • Spermatids differentiate into spermatozoa with specialized structures (head, midpiece, tail).
  • DNA compacted during this phase, becomes transcriptionally inactive.

Hormonal Regulation of Spermatogenesis

• Key Hormones:
  • Follicle Stimulating Hormone (FSH): Stimulates Sertoli cells, crucial for germ cell proliferation and differentiation.
  • Luteinizing Hormone (LH): Stimulates Leydig cells to produce androgens (testosterone).
  • Inhibin: Produced by Sertoli cells to suppress FSH production, maintaining hormonal balance.
  • Androgen Binding Protein: Maintains high local concentrations of androgens necessary for spermatogenesis.

Spermiation and Sperm Release

• Process of releasing spermatozoa from Sertoli cells into the lumen of seminiferous tubules.
• Involves loosening tight junctions between Sertoli cells.

Epididymis Functions

• Maturation of spermatozoa to gain motility, takes approximately 14 days.
• Involves high concentrations of sperm via fluid removal from the epididymal lumen.
• Protection and storage of sperm in the cauda epididymis.

Semen Composition

• Seminal plasma: noncellular fluid component from accessory glands (e.g., prostate, vesicular glands) and epididymis.
• Provides a buffering environment for sperm during ejaculation.