Which embryologic structure forms the definitive kidney?

Which embryologic structure forms the definitive kidney?

• A. Metanephros
• B. Pronephros
• C. Mesonephros
• D. Ureteric bud

Answer: (A)

The definitive kidney comes from the metanephros. In human development, pronephros and mesonephros appear early but are transient and regress, while the metanephros forms later and becomes the permanent kidney. It arises when the ureteric bud, an outgrowth of the Wolffian duct, induces the surrounding metanephric mesenchyme (blastema). The metanephric mesenchyme differentiates into the nephron components (glomerulus, proximal and distal tubules, loop of Henle), and the ureteric bud forms the collecting system (collecting ducts, calyces, renal pelvis, ureter). Thus, the kidney’s definitive structure is derived from the metanephros, with the collecting system contributed by the ureteric bud.

The definitive kidney comes from the metanephros. In human development, pronephros and mesonephros appear early but are transient and regress, while the metanephros forms later and becomes the permanent kidney. It arises when the ureteric bud, an outgrowth of the Wolffian duct, induces the surrounding metanephric mesenchyme (blastema). The metanephric mesenchyme differentiates into the nephron components (glomerulus, proximal and distal tubules, loop of Henle), and the ureteric bud forms the collecting system (collecting ducts, calyces, renal pelvis, ureter). Thus, the kidney’s definitive structure is derived from the metanephros, with the collecting system contributed by the ureteric bud.