Renal Pelvis

The renal pelvis or pyelum is the funnel-like dilated proximal part of the ureter in the kidney. In humans, the renal pelvis is the point of convergence of two or three major calyces. Each renal papilla is surrounded by a branch of the renal pelvis called a calyx. The major function of the renal pelvis is to act as a funnel for urine flowing to the ureter. The renal pelvis is the location of several kinds of kidney cancer. Its mucous membrane is covered with transitional epithelium, and an underlying lamina propria of loose to dense connective tissue. Various collecting ducts within the medullary pyramids merge to form papillary ducts, which drain eventually into the renal pelvis through the medullary papillae. Urine collects in the renal pelvis and drains out of the kidney through the ureter.