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Etymology: L, colligere, to gather, tubulus, small tube
any one of the many relatively straight tubules of the kidney that funnel urine into papillary ducts in the renal pelvis. The small collecting tubules play an important role in maintaining the fluid balance of the body by allowing water to osmose through their membranes into the interstitial fluid in the renal medulla. Antidiuretic hormone in the blood makes the collecting tubules permeable to water. If no antidiuretic hormone is present in the blood, membranes of the collecting tubules are practically impermeable to water. See also Bowman's capsule, kidney.
One of the small ducts that receive urine from several renal tubules, which join together to provide a passage for the urine to larger straight collecting tubules (papillary ducts of Bellini) that open into the pelvis of the kidney.See: kidney for illus
See also: tubule