Spermatogenesis

• Spermatogenesis

  The process of sperm production in male
• Spermatogenesis


  • Involves meiosis
  • 2 cell successive cell divisions in gamete formation producing nuclei with half the full number of chromosome
  • Begins during puberty
  • Occurs in seminiferous tubules
• Anatomy of spermatogenesis

  • Seminiferous tubules
  • Spermatic cord
  • Testicular veins
  • Testicular artery
  • Vas deferens
  • Epididymis
• Anatomy of a sperm

  • Acrosome
  • Plasma membrane
  • Nucleus
  • Centriol
  • Mitochondria
  • Terminal disc
  • Axial filament
  • Mid (connecting) piece
  • Head
  • Tail
• Spermatogonia

  • Primitive stem cell
  • Stimulated by FSH
  • Divide by mitosis to produce more spermatogonia
• Spermatocytogenesis


  1. Pairing and crossing over of chromosomal segments in prophase I

  2. Homologous pairs arrange on equator in metaphase I

  3. Homologous pairs separate to opposite poles in anaphase I

  4. 2 secondary spermatocytes form after telophase I

  5. Meiosis II follows immediately without DNA replication

  6. 2 secondary spermatocytes undergo meiosis II to form 4 spermatids
• Spermatids


  Rounded cells that modify to assume specific shape of the sperm
• Spermiogenesis


  1. Golgi apparatus forms acrosomal cap

  2. Nucleus is condensed

  3. Centriols make collar around neck

  4. Microtubules form flagellum

  5. Mitochondria arrange as spiral around neck

  6. Excess cytoplasm cast off as residual body

  7. Cytoplasmic bridges break and sperms release from Sertoli cells
• It takes about 22 days to complete meiosis I
• It takes about 64-72 days to go from a spermatogonium to a sperm
• Hormonal regulation of testicular function

  • GnRH (gonadotropin-releasing hormone) secreted by hypothalamus
  • FSH and LH secreted by anterior pituitary
  • FSH stimulates formation of ABP by nurse cells
  • LH stimulates interstitial cells to secrete testosterone
• Rising levels of testosterone and increased inhibin


  Feedback inhibition on the hypothalamus and pituitary