Papillary ducts

Papillary Duct
Position of the papillary duct in the kidney
Details
Precursor	Ureteric bud
System	Urinary System
Artery	vasa recta
Latin	ductus papillaris
Dorlands /Elsevier	d_29/12314994
TH	H3.06.00.1.00086
Anatomical terminology []

Papillary (collecting) ducts are anatomical structures of the kidneys, previously known as the ducts of Bellini. Papillary ducts represent the most distal portion of the collecting duct system. They receive renal filtrate (precursor to urine) from several medullary collecting ducts and empty into a minor calyx. Papillary ducts continue the work of water reabsorbtion and electrolyte balance initiated in the collecting tubules.

Medullary collecting ducts converge to form a central (papillary) duct near the apex of each renal pyramid. This "papillary duct" exits the renal pyramid at the renal papillae. The renal filtrate it carries drains into a minor calyx as urine.

The cells that comprise the duct itself are similar to rest of the collecting system. The duct is lined by a layer of simple columnar epithelium resting on a thin basement membrane. The epithelium is composed primarily of principle cells and α-intercilated cells.383

The simple columnar epithelium of the collecting duct system transitions into urothelium near the junction of a papillary duct and a minor calyx.

These cells work in tandem to reabsorb water, sodium, and urea and secrete acid and potassium. The amount of reabsorbtion or secretion that occurs is related to needs of the body at any given time. These processes are mediated by hormones (aldosterone, vasopressin) and the osmolarity (concentration of electrically charged chemicals) of the surrounding medulla.