Male genital system

Module A
Male Genital System
Martin Špaček
Histology and Embryology
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Pictures from:
Junqueira et al.: Basic histology
Kierszenbaum: Histology and cell biology
Rarey, Romrell: Clinical human embryology
Sadler: Langman’s medical embryology
Tonar: Prenatální vývojová stadia některých savců (http://www.lfp.cuni.cz)
Young, Heath: Wheather’s functional histology
http://www.med.unc.edu/embryo_images
Male Genital System
Development
• Development of the gonads
• Development of the genital ducts
• Development of the external genitalia
Development of the Gonads
• Sex of the embryo genetically determined
at the time of fertilization
• Indifferent gonad until the 7th week of
development
• Three sources of the cells:
– coelomic epithelium
– underlying mesenchyme
– primordial germ cells
Indifferent Gonads
• Genital ridges (3rd week)
– proliferation of the coelomic epithelium
– condensation of the underlying mesenchyme
Indifferent Gonads
• Germ cells migrate along the dorsal mesentery
from the yolk sac
• The cells invade genital ridges in the 6th week
Indifferent Gonads
• Coelomic epithelium proliferate forming
the primitive sex cords
Development of the Testis
• Y chromosome – SRY gene → TDF (testisdetermining factor)
• Under influence of the TDF primitive sex cords
form testis (medullary) cords
Development of the Testis
• Testis cords differentiate into the
seminiferous tubules:
– primitive germ cells
– sustentacular cells of Sertoli
• produce MIS (Müllerian inhibiting substance)
(=AMH – anti-müllerian hormone)
– intersticial cells of Leydig
• located between the tubules
• derived from the mesenchyme
• produce testosterone
Development of the Genital Ducts
• Indifferent stage
– mesonephric (Wolffian) ducts
– paramesonephric (Müllerian) ducts
Development of the Genital Ducts
• In the male MIS (=AMH) causes
regression of the paramesonephric
(Müllerian) ducts
Development of the Genital Ducts
• Mesonephric tubules → ductuli efferentes
• Mesonephric duct → duct of epididymis, ductus
deferens, ejaculatory duct, seminal vesicle
Development of the External Genitalia
• Indifferent stage (until the 8th week)
– genital tubercle
– cloacal folds → urethral folds
– genital swellings → labioscrotal swellings
At approximately the 8th week of
development
External Genitalia in the Male
• indiferent stage
• male genital
– testosterone
• genital tubercle
• urogenital folds
• genital swellings
• penis
• spongious urethra
• scrotum
External Genitalia in the Male
External Genitalia in the Male
• Hypospadias
– incomplete fusion of the urethral folds
External Genitalia in the Male
• Epispadias
– urethral opening on the dorsum of the
penis (rarer than hypospadias)
External Genitalia in the Male
• Testicular feminization
syndrome
– 46, XY
– the external
appearance of normal
females
– tissues of the external
genitalia are
unresponsive to the
testosterone
Descent of the Testis
• Initially located in the urogenital ridge
• Later move into the scrotum (through the
inguinal canal)
Descent of the Testis
• The testes arrive in the scrotum at
about the time of birth
• Cryptorchism (undescended testis)
– unable to produce spermatozoa
– increased risk of tumor formation
Histology of the Male Genital
System
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Testes
Excretory genital ducts
Accessory genital glands
Penis
Testes
• Tunica albuginea
– dense connective
tissue
• Lobuli testis
– seminiferous
tubules
– interstitium
Seminiferous Tubules
• Seminiferous (germinal) epithelium
– Sertoli (supporting) cells
– the cells of the spermatogenic lineage
Spermatogenesis
• Spermatogonia (in contact with the basal lamina)
– at sexual maturity undergo a series of mitoses
• Primary spermatocytes (the largest cells, 46
chromosomes) → undergo 1st meiotic division
• Secondary spermatocytes (23 chromosomes)
→ undergo
2nd meiotic division
• Spermatides
Spermiogenesis
• Spermatides undergo a complex process of
differentiation producing speratozoa
Sertoli Cells
• Support, protection of the developing speratozoa
• Phagocytosis, production of the MIS...
• Bound together by occluding junctions – blood
testis barrier
Intersticial Tissue
• Connective tissue, blood and lymphatic
vessels, nerves
• Leydig (intersticial) cells
– produce testosterone
Slide M1 – testes HE
Slide M1 – testes HE
Slide M1 – testes HE
Intratesticular Genital Ducts
• Tubuli recti
• Rete testis
• Ductuli efferentes
• Cuboidal epithelium
– unciliated & ciliated
cells
Excretory Genital Ducts
• Ductus epididymis
– single highly coiled
tube
– pseudostratified
columnar epithelium
– stereocilia (long,
branched microvilli)
• Functions:
– sperm maturation,
storage, transport
Slide M2 – Epididymis (H&E)
Slide M2 – Epididymis (H&E)
Excretory Genital Ducts
• Ductus deferens
– straight tube
– folded mucosa
– pseudostratified
epithelium
– thick layer of smooth
muscle
• inner and outer layer
longitudinal
• middle circular
Slide M3 – Spermatic Cord (H&E)
Slide M3 – Spermatic Cord (H&E)
Accessory Genital Glands
• Seminal vesicles
• Prostate
• Bulbourethral glands
Seminal Vesicles
• Two coiled tubes (15 cm)
• Folded mucosa
• Pseudostratified columnar
epithelium
• Thin smooth muscle layer
• Produce 50-70% of the
seminal fluid
– spermatozoa-activating
substances (fructose)
Slide M4 – Seminal Vesicles (H&E)
Slide M4 – Seminal Vesicles (H&E)
Prostate
• 30-50 tuboalveolar glands
– produce prostatic fluid
– concretions in the lumen
• Rich fibromuscular stroma
• Fibroelastic capsule
• Three zones of glands:
– central zone
– peripheral zone
• prostatic cancer
– transition zone
• benign hyperplazia
Slide M5 - Prostate (H&E)
Slide M5 - Prostate (H&E)
Slide M6 - Prostate (WvG)
Bulbourethral Glands of Cowper
• Tuboalveolar glands
• Simple cuboidal epithelium
– secretes mucus
Penis
• Three masses of
erectile tissue
– corpora cavernosa
(covered by tunica
albuginea)
– corpus spongiosum
( surrounds the
urethra)
Slide M7 - Penis (HE)