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Urogenital devolopment
1. The document discusses the development of the urinary and genital systems from primordia to fully formed organs, including the development of the kidneys, gonads, genital ducts, bladder, and external genitalia. 2. It describes the sex differentiation of the gonads, with the testes developing in males due to SRY and the ovaries developing in females in the absence of SRY. 3. Various congenital malformations are also summarized such as cryptorchidism, hermaphroditism, and hypospadias.
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Urogenital devolopment
- 1. Development of Urinary& Genital systems Human anatomy department, As. Prof. Yeryomin Anton
- 2.
- 3. I. Development ofUrinary System 1. Development of Kidney and Ureter 1.1 Primordia: Intermediate mesoderm: •Cervical part → nephrotomes •Caudal part → nephrogenic cords.
- 4. 1.2 Pronephros: Nephrotomes →pronephric tubules and duct → pronephros → degenerates. 1.3 Mesonephros: 1) Nephrogenic cord → mesonephric ridge → mesonephros
- 5. 2) Mesonephric tubules→ most disappear; mesonephric duct → open into cloaca.
- 6. 1.4 metanephros 1) Primordia:ureteric bud and metanephric blastema
- 7. 2) ureteric bud→ ureters, renal pelvis, calyces, collecting tubules Mesonephric duct
- 8.
- 9. 3) Metanephric blastema→ nephrons → Bowman's capsule, renal tubules → open connection to collecting tubules
- 10. 4) Kidneys ascend→ abdomen
- 11. 2. Formation ofBladder and Urethra Primordium: urogenital sinus 1) upper part → urinary bladder → continuous with allantois (obliterated later)
- 12. 2) Middle partof urogenital sinus → urethra; 3) Lower part → penile urethra in males, vestibule in females.
- 13. 3. Congenital Malformations 3.1Polycystic kidney •Abnormal development of the collecting system, or failure of the collecting tubules and nephrons to join; •Kidney contains many cysts, and failure of renal function may be caused.
- 14. Congenital cystic kidneysCongenitalcystic kidneys Type 1 – Polycystic kidneys found in infants Bilateral and results in early death Giant or sponge kidneys Large renal pelvis and calyces Type 2 – Cysts are variable in size and shape – Usually unilateral – Affected kidney non functional
- 15. Congenital cystic kidneysCongenitalcystic kidneys (cont.)(cont.) Type 3 – Affected kidneys contain both normal and abnormal tissue – Both kidneys involved – Autosomal dominant gene Trisomy of 13-15, 18, 21, 22 Type 4 – Caused by urethral obstruction – If severe early death Type 5 – Manifests during adult life, death by 50. – Autosomal dominant
- 16. 3.2 Pelvic kidney •Failureof kidney to ascend and still in the pelvis. 3.3 Horseshoe kidney •Both kidneys fail to ascend, and their lower poles fuse together.
- 17. Horseshoe (fused) kidneyHorseshoe(fused) kidney Fusion of two kidneys at their lower end – Tissue that connects kidneys = isthmus 1:400 Trisomy 13-15; 18, 21, Turner’s syndrome, mosaicism In rats horseshoe kidney can be produced experimentally by creating vitamin A deficiency
- 19. 3.4 Double ureter •Earlysplitting of ureter completely or partially; •Ureters open into bladder separately, or unite and open as usual.
- 20. 3.5 Urachal fistula •Causedby persisting allantois. •Urine may drain from the umbilicus.
- 21. II. Development ofGenital System 1. Development of Gonads 1.1 Primordia: gonadal ridges (coelomic epithelium + mesenchyme), primordial germ cells.
- 22. 1.2 Indifferent stage: •Gonadalridges → primary sex cords. •Yolk sac → primordial germ cells migrate into primary sex cords
- 23. 1.3 Development oftestis 1) Y → SRY → primary sex cords → medulla → testicular cords → seminiferous tubules → ↗epithelial cells → Sertoli cells ↘primordial germ cells → spermatogonia
- 24. 2) Mesenchyme (surface)→ tunica albuginea; (between sex cords ) → Leydig cells → (androgens)
- 25. 1.4 Development ofovary 1) XX (no SRY) → primary sex cords → medulla → degenerate 2) Coelomic epithelium → secondary sex cords (with primordial germ cells )
- 26. 3) Secondary sexcords → cell clusters → germ cells → oogonia epithelial cells → follicular cells Primordial follicles 4) Oogonia → primary oocyte → no oogonia at birth.
- 27. 1.5 Descent ofthe testis 1) Mesenchyme → gubernaculums ( testis -- genital swelling)
- 28. 2) Rapid bodygrowth gubernaculum shortening → testis descent → inguinal canal → scrotum
- 29. 3) Peritoneal sac→ vaginal process → scrotum → tunica vaginalis 4) Proximal part of vaginal process → obliterated at birth.
- 30. 2. Development ofGenital Duct 2.1 Primordia: mesonephric duct, paramesonephric duct.
- 31. 2.2 Indifferent stage 1)Coelomic epithelium → paramesonephric ducts: • cranial end → body cavity; • caudal ends fuse → uterine canal. 2) Tip of uterine canal → urogenital sinus → sinus tubercle.
- 32. 2.3 Development ofmale genital duct 1) Androgens (Leydig cells)→ •mesonephric duct → ductus epididymis, ductus deferens, ejaculatory duct, seminal gland; •mesonephric tubules → efferent ductules of testis.
- 33. 2) Anti-Mullerian ducthormone (Sertoli cells)→ paramesonephric ducts regress.
- 34. 2.4 Development offemale genital duct (no A & AMH) 1) Paramesonephric duct → uterine tube; Uterine canal → uterus, upper 1/3 of vagina.
- 35. 2) Sinus tubercle→ vaginal plate → canalized → lower 2/3 of vagina. 3) Mesonephric ducts → degenerate.
- 36. 3. Development ofexternal genitalia 3.1 Primordia: urogenital folds, genital tubercle, urogenital groove, labioscrotal swellings.
- 37. 3.2 Development Male (A)Female(no A) genital tubercle phallus clitoris urogenital folds lateral wall of urethra labia minora labioscrotal swellings scrotum labia majora urogenital groove penile urethra vestibule
- 38. 4. Congenital Malformations 4.1Cryptorchidism •Failure of one or both testes to descend into scrotum; •Seeming to be due to abnormal androgen production; •Testes may remain in abdomen or in inguinal canal.
- 39. 4.2 Congenital inguinalhernia •Failure of vaginal process to close; •Intestinal loops may descend into scrotum.
- 40. 4.3 Abnormalities ofthe uterus •Defects of fusion of caudal ends of paramesonephric ducts; •May cause double uterus, bicornuate uterus, uterus septus, etc.
- 41. 4.4 Vaginal atresia Causedby failure of vaginal plate to form or to be canalized.
- 42. 4.5 Hermaphroditism 1) Truehermaphrodite has gonad and external genitalia of both sexes. rarely observed. 2)Pseudohermaphrodite •Has either testes (male) or ovaries (female); •External genitalia resembling opposite sex; •Inadequate (male) or excessive (female) androgen production.
- 43. 4.6 Testicular feminizationsyndrome •44+XY chromosome complement; •Devoid of androgen receptors; •Testes in inguinal region, no spermatogenesis; •External genitalia as in females; no uterine tubes, uterus.
- 44. 4.7 Hypospadias •Incomplete fusionof urogenital folds; •Abnormal opening of urethra along ventral penis.
- 45. SUMMARY 1. Primordia anddevelopmental features of gonads & kidneys. 2. Sex differentiation of the gonads. 2. 3. Differentiation of the urogenital sinus; 4. Sex differentiation of the genital ducts. 5. Congenital malformations of genital system.