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Reproduction

Reproduction. Chapter 27. Male Reproductive System. Reproductive organs Testis Scrotum Reproductive tract Epididymis Vas Deferens Spermatic cord Accessory glands & organs Seminal vesicles Prostate gland Bulbourethral gland Penis. Gamete Production. Testes Spermatozoa (sperm)

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Reproduction

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  1. Reproduction Chapter 27

  2. Male Reproductive System • Reproductive organs • Testis • Scrotum • Reproductive tract • Epididymis • Vas Deferens • Spermatic cord • Accessory glands & organs • Seminal vesicles • Prostate gland • Bulbourethral gland • Penis

  3. Gamete Production • Testes • Spermatozoa (sperm) • ~100-300 million/ day • Production begins at puberty • Spermatogenesis- VERY temperature sensitive • Optimal temperature ~3-4C below body temp

  4. Pendulous Testes

  5. Scrotum • Bi-chambered external pouch of skin • Function • Houses testes • Protects testes • Regulates testicular temperature • Scrotum modifications for temperature regulation & protection • Low insulation- sparse hair & thin skin • Sweat glands • Vascularization- countercurrent blood flow • Musculature • Ennervation

  6. Low Insulation • Little insulating fat • Sparce hair • Sweat glands

  7. Musculature • Dartos muscle (tunic) • Muscle inserting into scrotal skin • Contraction tenses skin of scrotum & raises testis • wrinkling • Cremaster muscle • Surrounds testis • Contraction pulls testis closer to body • Cold- contraction • Warm- relaxation

  8. Testes Vascularization • Pampiniform plexus • Countercurrent blood flow • Cool venous blood surrounds incoming arteries • Actively cools incoming blood & warms outgoing blood • Testes always surrounded by cool blood

  9. Most common curable cause of infertility Equivalent of varicose veins Varicocele

  10. Scrotum Nerves • Behavioral protection

  11. Testis • Paired gonads inside of scrotum • Surrounded by tunic • Tunica albuginea • Function • Spermatogenesis- sperm formation • Hormone production • Androgens- testosterone

  12. Tunica albuginea “White Coat”

  13. Testis Structure • Seminiferous tubules • Sertoli cells • Rete testis • Interstitial (Leydig) cells

  14. Seminiferous Tubules • Actual site of spermatogenesis • 800+ coiled tubes • Maximizes surface area • Bulk of testes tissue

  15. Spermatogenesis & Androgen Production Stimulated by Brain

  16. Interstitial (Leydig) Cells • Located between seminiferous tubules • Site of androgen production • Surrounded by capillaries • Stimulated to produce by increased levels of testosterone by Leuteinizing Hormone

  17. Interstitial (Leydig) Cells

  18. Interstitial (Leydig) Cells

  19. Testosterone Levels

  20. Testosterone Levels

  21. Testosterone Levels

  22. Sertoli Cells • Lots tight junctions in cells near basement membrane • Form blood testes barrier • Protects from pathogens, mutagens, immune cells

  23. Sperm Path Male reproductive tract continuous- Isolates sperm

  24. Rete Testis • Located within the testis • Site of merging seminiferous tubules exiting from testes • Common pathway for exiting sperm

  25. Male Reproductive Tract

  26. Epididymis • Testicular cap • Single coiled tubule • 6M long • Receives sperm from rete testis • Function • Secretes/absorbs nourishing fluid • Recycles damaged spermatozoa • Stores spermatozoa • Up to 2 weeks • Allows time for maturation

  27. Epididymis

  28. Epididymis

  29. Tunica Vaginalis Surrounds testes & epididymis Allows free movement of testes inside of scrotum

  30. Vas Deferens • Aka Ductus Deferens • Single tubule carries sperm from epididymis into abdominal cavity • 45 cm long • Muscular tube • Passes thru inguinal canal • Connects to urethra at prostate

  31. Vas Deferens

  32. Spermatic Cord • Tissue located within the inguinal canal • Combination of tissues • Vas deferens • Pampiniform plexus • Testicular tissue • Arteries & nerves • Muscle

  33. Inguinal Canal

  34. Testis Torsion

  35. Accessory Glands • Seminal vesicle • Prostate • Bulbourethral gland

  36. Accessory Glands • Secrete seminal fluid • Nourish, activate & protect sperm • Semen (seed) • Glandular secretions (99%) & sperm (1%) • ~2-5 mls per ejaculation • ~50-200 million sperm per ml of ejaculate • 100-700 million per ejaculation • 50 reach oocyte

  37. Seminal Vesicle • Paired elongate glands • Located posterior & inferior to bladder • Secretes (60% semen) • Fructose • “sugar” • Energy source • Prostaglandins • Activate sperm motility • Stimulate contractions of female reproductive tract • Fibrinogen • Clotting factors • Slows sperm

  38. Prostate • Large solid single gland • Located at base of bladder • Houses prostatic urethra • Secretes (20-30%) • Enzymes • Aid in activating sperm motility • Antibiotic • Mucus degradation • Alkaline fluid • Neutralize female reproductive tract • Citric acid, proteolytic enzymes • Antioxidants • ???secretions of unknown function

  39. Prostate Cancer • Most common cancer in men • 3rd most common cause of death in men • Disease of well developed nations • Diet & lifestyle • High fat diet • High testosterone levels • Cadmium exposure • Low rates in Japanese & vegetarians • By age 80 70% men will have it

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