Unilateral renal agenesis most commonly results from failure of which developmental event?
- A Failure of fusion of the two metanephric blastemas
- B Degeneration of the pronephros
- C Ureteric bud failing to develop or to induce the metanephric blastema ✓
- D Persistence of the mesonephric duct on that side
Correct answer: C. Ureteric bud failing to develop or to induce the metanephric blastema
Explanation
The definitive kidney develops when the ureteric bud, an outgrowth of the mesonephric duct, induces the surrounding metanephric blastema to differentiate into nephrons. If the ureteric bud fails to form or fails to contact and induce the blastema, the blastema degenerates and the kidney is absent on that side. Pronephros degeneration is a normal event, and fusion failure of blastemas produces a horseshoe kidney, not agenesis.
Reference: Langman's Medical Embryology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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