IS THE URINARY TRACT EPITHELIUM TALENTED AS THE RENAL TUBULAR EPITHELIUM ?

The urothelium serves as a barrier and a storage functions due to the specialized structure of the superficial cells and junctional complexes, while maintaining the urine composition similar to that generated by kidneys. The apical membrane of the urothelium has an asymmetric unit membrane (A UM) structure. Uroplakins (UPs), constituting the A UM, are the first specific urothelial differentiation markers described. Apical membranes also posses sodium channels along with other ion transport systems, that regulate transcellular ionic flux. The urothelium can also function as a secretor of urinary proteins and human growth hormone. UPs have the potential role for pathogenesis of primary vesicoureteral reflux and Echerichia coli infection. UPs are sensitive and specific markers for a tumor of urothelial origin. The urothelium can modify the urinary contents by reabsorbing or secreting specific solutes, and has an important functions similar that the renal tubular epithelium.