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The collecting duct system of the kidney consists of a series of tubules and ducts that physically connect nephrons to a minor calyx or directly to the renal pelvis.The collecting duct participates in electrolyte and fluid balance through reabsorption and excretion, processes regulated by the hormones aldosterone and vasopressin (antidiuretic hormone).
The renal calyces (sg. calyx) are conduits in the kidney through which urine passes. The minor calyces form a cup-shaped drain around the apex of the renal pyramids.Urine formed in the kidney passes through a renal papilla at the apex into the minor calyx; four or five minor calyces converge to form a major calyx through which urine passes into the renal pelvis (which in turn drains urine out ...
Perturbed renal papillary development has also been shown to be associated with onset of functional obstruction and renal fibrosis. [5] [6] [7] Renal papillary damage has also been associated with nephrolithiasis and can be quantified according to the papillary grading score, which accounts for contour, pitting, plugging and Randall's plaque. [8]
The collecting duct system begins in the renal cortex and extends deep into the medulla. As the urine travels down the collecting duct system, it passes by the medullary interstitium which has a high sodium concentration as a result of the loop of Henle's countercurrent multiplier system. [1]: 67
Both hormones exert their effects principally on the collecting ducts. Tubular secretion occurs simultaneously during re-absorption of filtrate. Substances, generally produced by body or the by-products of cell metabolism that can become toxic in high concentration, and some drugs (if taken).
To achieve such balance between water and ions, the loop of Henle coordinates its function with the collecting duct to regulate the amount of water to reabsorb or to excrete. While the loop of Henle makes the medulla of the kidney salty, the collecting duct regulates the permeability of water that could be reabsorbed to such salty environment.
In a microscopic context, there are four major histologic subtypes of renal cell cancer: clear cell (conventional RCC, 75%), papillary (15%), chromophobic (5%), and collecting duct (2%). Sarcomatoid changes (morphology and patterns of IHC that mimic sarcoma, spindle cells) can be observed within any RCC subtype and are associated with more ...
The renal cortex is the outer portion of the kidney between the renal capsule and the renal medulla. [1] In the adult, it forms a continuous smooth outer zone with a number of projections (cortical columns) that extend down between the pyramids.