Why do the medullary pyramids appear different from the renal cortex and renal columns?

Answer and explanation.

The renal cortex is the outer layer of the kidney in contact with renal capsule. Renal pyramids are distinct conical or triangular structures in renal medulla: base abuts cortex, tip (renal papilla) projects into renal sinus .

Renal columns are bands of cortical tissue separate adjacent renal pyramids, and extend into medulla, they have distinctly granular texture.

The medulla is divided into the pyramids, which are pyramidal in shape. The renal columns separate the pyramids, and are actually extensions of the cortex. These can clearly be seen in a kidney cut in half in a coronal plane. Each renal pyramid had a renal papilla, which points inwards, opening into a minor calyx. Each pyramid also has a base, which is closest to the cortex.