Which structure contains nephrons and is the outermost layer of the kidney?

• A. Cortex
• B. Renal capsule
• C. Renal pelvis
• D. Glomerulus

Answer: (A)

Nephrons reside mainly in the kidney’s outer region, the cortex, making it the layer that houses the functional units of filtration and reabsorption. The cortex contains the renal corpuscles (glomerulus with Bowman's capsule) and much of the proximal and distal tubules, where most filtration and early processing occur. The renal capsule is simply the protective outer covering around the kidney, not a site for nephrons. The renal pelvis is the central urine-collecting area, not where nephrons are located. The glomerulus is a component of a nephron located within Bowman's capsule in the cortex, so it’s part of the nephron structure rather than the outer layer itself. Therefore, the cortex is the outermost structure that contains nephrons.