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Mesoderm-3 rd week

This article discusses the development of the urogenital system, including the formation of the kidneys and gonads, as well as common renal anomalies. Key topics include the development of the mesoderm, differentiation of gonads, and the descent of the testes.

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Mesoderm-3 rd week

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  1. Mesoderm-3rd week

  2. Pronephros & mesonephros-4th week

  3. Urogenital ridge4th week

  4. Urinary system-4th week

  5. 4-5 week

  6. Mesonephric vesicle

  7. Mesonephric tubules

  8. metanephros

  9. Metanephric kidneys

  10. Metanephric kidneys

  11. 5th week

  12. 6th-7th week

  13. 8th-9th week

  14. 12th week

  15. Relocation of Kidneys 6th & 7th week

  16. Relocation of Kidneys 8th & 9th week

  17. Renal anomalies • Renal agenesis – Potter Sequence • Renal dysplasias – multicystic dysplastic kidney • Cong. polycystic kidney D. • Autosomal dominant • Autosomal recessive • Duplication of ureter

  18. Renal AnomaliesDisorders due to malrotation Often associated with ectopic kidneys • Malrotated kidneys • Supernumerary kidneys • Fused kidneys- crossed renal ectopia • Divided kidney with bifid ureter

  19. Renal AnomaliesDisorders due to positional changes • Accessory renal arteries • Accessory renal veins • Pelvic kidneys • Horseshoe kidneys • Pancake kidneys

  20. Bladder Anomalies • Urachal fistula • Urachal sinus • Urachal cyst • Exstrophy of bladder • Exstrophy of cloaca

  21. Multiple Renal Arteries

  22. Multiple Renal Veins

  23. Unilateral Renal Agenesis

  24. Pelvic Kidney

  25. Malrotation of kidney

  26. Crossed Renal Ectopia

  27. Discoid Kidney

  28. Supernumerary Kidney

  29. Urachal Cyst

  30. Urachal Sinus

  31. Urachal Fistula

  32. Development of gonads • 4th week- primordial germ cells • 5th week – Gonadal ridge • 6th week – Incorporation of cells into gonadal cords • Upto 7th week – Indifferent gonad • Y- chrosomome- SRY gene for TDF in sex determining region of y ch. • Y chromosome has a testis determining effect on medulla of gonad • Type of gonad formed will further differentiate development of genital ducts and external genitalia

  33. Development of gonad • Mesothelium- (of post. Abd. Wall) • Mesenchyme • Primordial germ cells- • large sperical cells among endoderm of yolk sac near allantois • Gonadal ridge- • mesothelial thickening on medial side of mesonephros + mesenchyme • Prim. Germ cells migrate along dorsal mesentery to gonadal ridge

  34. Indifferent gonad Gonadal Ridge Gonadal cords (Fingerlike epithelial cords) Gonad consists of cortex & medulla xy xx Testis ovary

  35. Indifferent Gonad

  36. Indifferent Gonad

  37. Differentiation of Gonads

  38. Ovaries

  39. Testis • Condensation of cords • Extension into medulla • Branching & anastomoses-rete testis • Tunica albuginea develops • Connection of cords with surface nis lost • S. tubules, T recti & rete T • Mesenchyme- interstitial cells in 8th wk- hormones • S tubules remain solid till puberty

  40. Hormones in male • 8-12 wk- peak of HCG --- Testosterone & androstenedion from Leydig cells • MIS / AMH from Sertoli cells

  41. Mesonephric duct & tubules • Mesonephric tubules --- Efferent ductule + paradidymus in male • Epoophoron & paroophoron in female • M duct prox. Part --- duct of epididymus, appendix of epididymus • M duct distal part ---URETERIC BUD + ductus deferens, ejaculatory ducts & seminal gland • Appendix vesiculosa, duct of epoophoron & Gartner’s duct in female + URETERIC BUD

  42. Descent of the Testis • The process vaginalis, (evagination of peritoneum), develops ventral to the gubernaculum and herniates through the abdominal wall along the path formed by the gubernaculum • The vaginal process carries extensions of the layers of the inguinal canal • In males these layers also form the coverings of the spermatic cord and testis • The opening in the transversalis fascia produced by the vaginal process becomes the deep inguinal ring • The opening created in the external oblique aponeurosis forms the superficial inguinal ring.

  43. Descent of Testes • Enlargement of the testes • Atrophy of the mesonephroi • Atrophy of the paramesonephric ducts • Enlargement of the processus vaginalis • Enlargement of fetal pelvis • Trunk elongates • Androgens • Descend retroperitoneally • Gubernaculum • Increased intra abdominal pressure due to viscera • .

  44. Development of Inguinal Canals • The inguinal canals form pathways for the testes to descend from the abdomen into the scrotum • Develop in both sexes because of the indifferent stage • As the mesonephros degenerates, a ligament – the gubernaculum – descends on each side of the abdomen from the inferior pole of the gonad • The gubernaculum passes obliquely through the developing anterior abdominal wall at the site of the future inguinal canal • The gubernaculum attaches caudally to the internal surface of the labioscrotal swellings (future halves of the scrotum or labia majora).

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