ANATOMY

Detailed explanation-1: -The outer, reddish region, next to the capsule, is the renal cortex. This surrounds a darker reddish-brown region called the renal medulla. The renal medulla consists of a series of renal pyramids, which appear striated because they contain straight tubular structures and blood vessels.

Detailed explanation-2: -The mature renal medulla consists of the medullary collecting ducts, loops of Henle, vasa recta (straight capillaries) and the interstitium (lipid-laden interstitial cells, lymphocyte-like cells and pericytes). The main function of the medulla is to regulate concentration of the urine.

Detailed explanation-3: -The medulla is divided into 8-18 conical regions, called the renal pyramids; the base of each pyramid starts at the corticomedullary border, and the apex ends in the renal papilla which merges to form the renal pelvis and then on to form the ureter.

Detailed explanation-4: -The pyramids appear striped because they are formed by straight parallel segments of nephrons’ Loops of Henle and collecting ducts.

Detailed explanation-5: -The Kidneys Are Composed of Three Main Sections Each kidney consists of an outer renal cortex, an inner renal medulla, and a renal pelvis. Blood is filtered in the renal cortex. The renal medulla contains the renal pyramids, where urine formation takes place.