Self-assessment Questions

41 The kidney and ureter

• 1. What are the stages of embryological development of the kidney?

  Show Answer

  Correct answer:

  Initially, a pronephros develops in the posterior wall of the coelomic cavity. This is replaced by the mesonephric system, which comprises a long ridge of mesoderm, the mesonephros, with its duct, the mesonephric (Wolffian) duct. The mesonephros itself then disappears except that, in the male, some of its ducts become the efferent tubules of the testis. At the lower end of the mesonephric duct a diverticulum develops. This diverticulum becomes the ureteric bud, on top of which develops a cap of tissue, the metanephric mesenchyme. The metanephric mesenchyme gives rise to the glomeruli and the proximal part of the renal duct system. The ureteric bud forms the ureter, renal pelvis, calyces and distal ducts. The mesonephric duct atrophies in the female, the remnant being called the epoöphron, and in the male it gives rise to the epididymis and the vas deferens. The kidney originally develops in the pelvis of the embryo and then migrates cranially, acquiring a progressively more proximal arterial blood supply as it does so. This complex developmental process explains the high frequency with which congenital anomalies of the kidney, the ureter and the renal blood supply are found.

• 2. What is the first developmental structure of the kidney?

  Show Answer

  Correct answer:

  Initially, a pronephros develops in the posterior wall of the coelomic cavity.

• 3. What replaces the pronephros during development of the kidney?

  Show Answer

  Correct answer:

  This is replaced by the mesonephric system, which comprises a long ridge of mesoderm, the mesonephros, with its duct, the mesonephric (Wolffian) duct.

• 4. What is the Wolffian duct?

  Show Answer

  Correct answer:

  This is the mesonephric duct, which forms as part of the development of the kidney.

• 5. What happens to the mesonephric system during the development of the kidney?

  Show Answer

  Correct answer:

  The mesonephros itself disappears except that, in the male, some of its ducts become the efferent tubules of the testis. At the lower end of the mesonephric duct a diverticulum becomes the ureteric bud, on top of which develops a cap of tissue, the metanephric mesenchyme.

• 6. What develops from the metanephric mesenchyme during formation of the kidney?

  Show Answer

  Correct answer:

  This gives rise to the glomeruli and the proximal part of the renal duct system. The ureteric bud forms the ureter, renal pelvis, calyces and distal ducts.

• 7. What happens to the mesonephric duct of the kidney in the female?

  Show Answer

  Correct answer:

  This atrophies in the female, the remnant being called the epoöphron.

• 8. What is the epoöphron?

  Show Answer

  Correct answer:

  This is the remnant of the atrophied mesonephric duct in the female.

• 9. What happens to the mesonephric duct of the kidney in the male?

  Show Answer

  Correct answer:

  In the male the mesonephric duct gives rise to the epididymis and the vas deferens.

• 10. Where does the kidney originally develop? How does this position change during growth?

  Show Answer

  Correct answer:

  The kidney originally develops in the pelvis of the embryo and then migrates cranially, acquiring a progressively more proximal arterial blood supply as it does so.

• 11. What are the most common renal anomalies?

  Show Answer

  Correct answer:

  (1) Pelvic kidney. (2) Absence of one kidney. (3) Polycystic kidneys. (4) Aberrant renal arteries. (5) Duplex system. (6) Hydronephrosis. (7) Horseshoe kidney.

• 12. Why does pelvic kidney occur?

  Show Answer

  Correct answer:

  As a result of failure of cranial migration of the developing kidney.

• 13. Why does horseshoe kidney occur?

  Show Answer

  Correct answer:

  Produced by fusion of the two metanephric masses across the midline.