Male Reproductive System

• Scrotum: sac which contains the testes, controls temperature
• Testes: male gonad, produce sec cells (sperm)
• seminiferous tubule: coiled ducts within the testes where immature sperm cells undergo division and differentiation
• epididymis: on the border of the testes, stores sperm cells for maturation
• Vas deferens: A tube that carries sperm from the epididymis to the urethra
• seminal vesicle: produces fluid that nourishes sperm and helps them swim (fructose)
• ejaculatory duct: regulates the movement of sperm
• prostate gland: contributes an alkaline base/buffer to the seminal fluid to neutralize the acidic environment of the vagina
• Cowper's gland: contributes a mucus coating to seminal fluid to help with the urethra environment
• Urethra: carries seminal fluid and urine to the exterior
• Interstitial cells: produces testosterone and are found outside the seminiferous tubule
• testosterone: stimulates spermatogenesis, and have a secondary male sex characteristic ("masculine" appearance)
• Sex hormonal control:

  1. Hypothalamus releases GnRH which then activates the pituitary gland
  2. FSH and ICSH or LH are then produced
• FSH: stimulates the production of sperm cells in seminiferous tubules and stimulates the sertoli cells
• LH or ICSH: stimulates the interstitial cells to produce testosterone
• Negative feedback 1:

  • High levels of testosterone detected
  • GnRH production slows
  • LH or ICSH production and release slows
  • Less testosterone is produced
• Negative feedback 2:

  • Sertoli cells release inhibin
  • inhibin slows the production of GnRH in the hypothalamus and FSH in the petuitary gland
  • decreased sperm production
• Parts of the sperm:

  • Head
  • Midpiece
  • Tail or flagellum
• The head contains the nucleus, acrosome (contains enzymes), and mitochondria.
• The midpiece contains the centrioles that form the tail and the capillaries that supply oxygen and nutrients to the cell.
• Sertoli Cells: are support cells for the sperm and are found in the seminiferous tubule
• Seminal fluid is produced by:

  • seminal vesicles: sugar (fructose)
  • prostate gland: pH (alkaline base)
  • Cowper's gland: mucus
• Spermatogenesis:

  • seminiferous tubules are lined with sperm-producing cells called spermatogonia (46 chromosomes)
  • During meiosis the spermatogonia divide into spermatocytes (23 chromosomes)
  • The spermatocytes (mature in the epididymis) then divide into spermatids