Male reproductive system

• It takes 74 days for formation of sperm from a primitive germ cell
• Stages of spermatogenesis:

  1. stage of proliferation
  2. stage of growth
  3. stage of maturation
  4. stage of transformation
• Spermiogenesis:

  Process by spermatids become matured spermatozoa.

  Changes that take place:

  1. condensation of nuclear material
  2. formation of acrosome, mitochondrial spiral filament and tail structures
  3. removal of extraneous cytoplasm
• Spermination

  Process by which matured sperms are released from sertoli cells into lumen of seminiferous tubules.
• Factors influencing spermatogenesis:

  1. sertoli cells
  2. hormones {necessary for spermatogenesis are:- FSH, LH, GH, testosterone, estrogen, inhibin, activin}
  3. increase in body temperature and diseases
• FSH - initiation of spermatogenesis

  Testosterone - maintenance of spermatogenesis

  Estrogen - necessary. Formed in sertoli cells by testosterone

  Luteinizing hormone - essential for secretion of testosterone from leydig cells

  Growth hormone - for general metabolic processes

  Inhibin - regulation of spermatogenesis
• Sertoli cells:

  supporting/ sustentacular/ nurse cells

  extending from basement membrane to lumen of seminiferous tubule

  Functions:

  1. support and nourish the spermatogenic cells till spermatozoa are released from them
  2. secrete enzyme aromatase which converts androgens into estrogen
  3. secrete androgen - binding protein essential for testosterone activity
  4. secrete estrogen - binding protein
  5. secrete inhibin which inhibits FSH release from anterior pituitary
  6. secrete activin (opposite effect of inhibin)
  7. secrete mullerian regression factor in fetal testes.
• Functions of testosterone:

  In fetal life :

  1. sex differentiation :- if testosterone is secreted from genital ridge in 7th week of intrauterine life, mullerian duct system disappears and male sex organs develop from wolffian duct
  2. development of accessory sex organs
  3. descent of testes
• Cryptorchidism:

  Congenital disorder where failure of descent of one or two testes from abdomen to scrotum. Male with untreated testes are prone to testicular cancer.

  Treatment: Inguinal canal broader than administration of testosterone or gonadotropic hormones. Inguinal canal narrower then surgery required
• Effect of testosterone on sex organs

  1. Penis, scrotum and testes are enlarged at least 8 folds between onset of puberty and 20 yrs of age

  2. Required for spermatogenesis
• Effect of testosterone on secondary characters

  • Development of musculature
  • Protein anabolic activity that increases bone matrix and deposition of calcium, causes early fusion of epiphyseal plate
  • Causes lengthening of pelvis, funnel like shape of pelvis, narrowing of pelvic outlet
  • Increase thickness of skin and ruggedness of subcutaneous tissue
  • Effect on hair distribution
  • Causes hypertrophy of laryngeal muscle, enlargement of larynx and lengthening, thickening of vocal cords
  • Increases BMR
  • Increases sodium reabsorption
  • Erythropoietic action