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Sperm passage

SEVEN UP

  • Seminiferous tubule
  • Epididymis
  • Vas Deferens
  • Ejaculatory ducts
  • N (nothing)
  • Urethra
  • Penis

Testes

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  • situated in the scrotum
  • 2 covering
    • tunica vaginalis
      • parietal & visceral layer
      • in between the layer: thin cavity with little fluid
    • tunica albugenia
      • fibrous capsule
      • thickened posteriorly (mediastinum)
      • septa divides the testis into lobules
        • 250-300
  • Functions
    • spermatogenesis
    • secretion of testosterone

Seminiferous tubules

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    • highly convoluted
    • situated within lobules
    • Lined by germinal epithelium
      • spermatogonium
      • primary & secondary spermatocyte
      • early & late spermatids
        • spermatogenesis –> mature spermatozoa
    • Opens to rete testes in the mediatinum

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Image: Spermatogenesis

Sertoli cells/ Sustentacular cells

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  • form the blood testis barrier
    • important because sperms are considered as foreign bodies
    • if enter blood, antibodies will kill it
  • supply nutrients
  • secrete testicular fluid
  • phagocytosis

Interstitial cells/Leydig’s cells

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  • lies in between seminiferous tubules
  • secretes testosterone

_____________________________________________________________________Duct system

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  • epididymis
    • long highly coiled tubule
    • lies on posterior surface of the testis
    • divided into head, body & tail
    • efferent ductules open to head
    • tail continuous with vas deferens
    • Function:
      • capacitates sperms
      • supplies nutrients to sperms
      • stores sperms
      • removes dead sperm
  • vas deferens
    • from tail of epididymis to the ejaculatory ducts
    • part of it in scrotum, part of it in pelvic cavity
    • very thick muscular wall with small lumen
    • Functions:
      • propels sperms during ejaculation
        • peristalsis of smooth muscles
  • ejaculatory duct
    • formed by union of vas deferens & duct of the seminal vesicle
    • passes through prostate gland
    • opens to the urethra
  • urethra (passage for urine & semen)
    • prostatic
      • midline urethral crest
      • prostatic sinuses on either sides
      • ejaculatory ducts open to seminal colliculus on the urethral crest
      • prostatic ducts open to prostatic sinuses
    • membranous
    • penile

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Accessory glands

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  • Seminal vesicle
    • located behind the bladder & above the prostate
    • join the vas deferens to form the ejaculatory ducts
    • 60% of seminal fluid
      • yellowish, viscous & alkaline
      • fructose & ascorbic acid
      • coagulating enzyme (vesiculase)
      • prostaglandins
  • Prostate gland
    • lies inferior to bladder
    • urethra & ejaculatory ducts passes through it
    • several ducts open to prostatic urethra
    • thich capsule
    • secretory unit embedded in a fibro-muscular stroma
    • secretions
      • acidic (citrate)
      • fibrinolysins
      • hyaluronidase
      • acid phosphatase
      • prostaglandins
      • PSA (prostate specific antigen)
  • Bulbo-urethral glands (Cowper’s glands)
    • lie inferior to prostate gland
    • ducts open to penile urethra
    • secretes
      • pure mucus
        • just before ejaculation to neutralise acidity of urine

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External genitalia

Scrotum

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  • sac of skin & superficial fascia
  • midline septum
  • hangs from root of the penis
  • testes suspended in it
    • provides optimal temperature for spermatogenesis

Penis

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  • Root
  • Shaft
    • skin over shaft is loose
    • forms a cuff over glans (prepuce)
  • Glans
    • urethral opens to exterior (vertical slit)

Structure of the penis

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  • 3 cylindrical bodies of erectile tissue
    • 2 corpora cavernosa
      • lies on both sides of the corpus spongiosum
      • proximal part covered with ischiocavernous muscles
    • 1 corpus spongiosum
      • expands distally to form the glans
      • whole length covered with bulbospongeosus muscle
  • Penile urethra passes through it
  • Functions:
    • copulation (sex)
    • passage of urine & sperm

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