Structural organization of the renal medulla: comparative and functional aspects

摘要: The renal medulla develops very differently among species, being more prominent in those with a high urinary concentrating capacity. Attempts to correlate structure and function must consider loops of Henle, collecting ducts, vessels, interstitium, pelvis. Two types long short, are distinguished. Numerical relationships between both differ species. Based on the epithelial lining short loop consists thick descending limb (pars recta proximal tubule), thin limb, ascending limb. Long loops, addition, have limb; their limbs different from site considerable interspecies differences. Collecting ducts form cortex by joining several nephrons. Patterns without arcade formation On entering inner medulla, fuse successively. duct epithelium principal intercalated cells whose individual functions subject debate. Blood vessels arranged strict pattern reflecting that, addition nourishment, unique requirements maintaining corticomedullary osmotic gradient be met. Ultrastructural organization medullary is less specific compared cortical vessels. simple type has vascular bundles consisting only de- vasa recta; complex type, also integrated into bundles. Functional implications this difference considerable. Striking differences occur