Emergency Ultrasound > Introduction > Physiology


The testes are composed of 90% seminiferous tubules (Sertoli and germ cells) and 10% interstitial (Leydig Cells, connective tissue, blood supply)

2 major functions of the testes:

I. Spermatogenesis occurs in the Seminiferous Tubules, takes approximately 70 days to complete, occurs continuously and is regulated by FSH, LH.

  • Seminiferous tubules
  • Rete testis
  • Epididymis storage and maturation of sperm
  • Vas/ductus deferens

3 major phases

  • Mitosis Spermatogonia (germ cells) _ Spermatocytes
  • Meiosis Spermatocytes (2n) _ Spermatids (1n) haploid like mature sperm
  • Spermiogenesis spermatids _ mature sperm (sheds cytoplasm, acrosome forms, etc)

Sertoli Cells have supportive function in providing nutrients to developing sperm cells, tight junctions to provide blood-testis barrier and secrete aqueous secretion into the lumen to aid sperm transport

II. Biosynthesis of Testosterone (T) Leydig Cells

Testosterone is synthesized from Cholesterol

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