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The Male Reproductive System

The Male Reproductive System. Components. Scrotum Testes Duct system Penis Accessory glands. Scrotum. Skin Dartos muscle (smooth) wrinkles Septum Cremaster muscle (skeletal) (lifts). Scrotum . Temperature Optimal for sperm development is 3 °C below body temp (~91 F)

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The Male Reproductive System

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  1. The Male Reproductive System

  2. Components Scrotum Testes Duct system Penis Accessory glands

  3. Scrotum • Skin • Dartos muscle (smooth) wrinkles • Septum • Cremaster muscle (skeletal) (lifts)

  4. Scrotum Temperature Optimal for sperm development is 3°C below body temp (~91 F) Controlled by muscles Spermatic cord Testicular artery Plexus of veins Nerves vas deferens (aka ductus defrens)

  5. Testes – gross anatomy • ~4 cm long, 2.5 cm wide • Tunica vaginalis • Tunica albuginea (capsule) • Septa • 250-300 lobules • Seminiferous tubules • Epididymis

  6. Descent of the Testes 3 mos. 7 mos. birth

  7. Seminiferous tubules • Spermatogenic cells • Spermatogenesis begins at puberty • ~400 million sperm/day

  8. Spermatogenic cells • Spermatogonia • On basal lamina • Mitosis • Primary spermatocytes • 1st meiotic division • Secondary spermatocytes • 2nd meiotic division • Spermatid • Haploid • 4 from each 1° spermatocyte 24.4b

  9. Seminiferous tubules Spermatogenesis Spermatogonia 1° spermatocyte 2° spermatocyte Spermatid

  10. Hormones • Spermatogenesis controlled by • FSH (follicle stimulating hormone) from pituitary • Testosterone from Leydig (interstitial) cells of testes • secretions from Sertoli cells

  11. Spermiogenesis Spermatid  spermatozoan Head Nucleus Acrosome (lysosome) Midpiece Base of tail Mitochondria Tail Long flagellum

  12. Spermiogenesis Spermatid  spermatozoan

  13. Sustentacular (Sertoli) cells Nurse cells Extend from basal lamina to lumen Connected to each other by tight junctions Nourish spermatogenic cells Transport spermatogenic cells Phagocytize excess cytoplasm Secretions regulate spermatogenesis

  14. Sustentacular cells 2 Sertoli cells with associated spermatogenesis cells.

  15. Interstitial (Leydig) cells Secretes testosterone sER for steroid production Controlled by LH from pituitary

  16. Ducts Epididymis Ductus deferens Ejaculatory duct (urethra)

  17. Epididymis Located in scrotum Between seminiferous tubules and vas deferens ~6 m long

  18. Epididymis • Pseudostratified columnar epithelium • With stereocilia (long microvilli) • Smooth muscle • Sperm mature and stored

  19. Ductus (vas) deferens • From scrotum to pelvis • Forms ejaculatory duct with seminal vesicle duct • Empties into prostatic urethra • Thick muscularis • Propels sperm during ejaculation

  20. Ductus deferens • Microscopic anatomy • Pseudostratified epithelium • Lamina propria • Muscularis • Inner longitudinal • Middle circular • Outer longitudinal

  21. Urethra Shared with urinary system Prostatic urethra Membranous urethra Spongy (penile) urethra

  22. Accessory Glands Seminal vesicle 60% of semen Fructose to nourish sperm

  23. Prostate Gland Prostate gland Surrounds prostatic urethra 30% of semen Supports sperm

  24. Penis • Thin skin • Spongy urethra • Erectile bodies • Corpus spongiosum • 2 corpora cavernosa • Capsule • Vascular spaces CC cs

  25. Erection Sexual excitement (parasympathetic)  blood flow to erectile bodies Squeezes veins shut  blood pressure in erectile bodies

  26. Ejaculation Sympathetic activation Peristaltic contraction of smooth muscles in ducts and glands - ejaculation Constriction of arteries  blood pressure in erectile bodies

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