ANATOMY

Detailed explanation-1: -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-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: -Kidney is divided into two zones, an inner medulla and an outer cortex. Cortex is the zone that occupies the peripheral zone of kidneys. The medulla is the inner region of the of the kidney. It is divided into a few conical masses known as the renal or medullary pyramids projecting into the calyces.

Detailed explanation-4: -The pyramids consist mainly of tubules that transport urine from the cortical, or outer, part of the kidney, where urine is produced, to the calyces, or cup-shaped cavities in which urine collects before it passes through the ureter to the bladder. The point of each pyramid, called the papilla, projects into a calyx.