Most of the urinary tract, including the bladder, is lined by a specific type of epithelium, which is called urothelium or uroepithelium. Urothelium belongs to the category of transitional epithelium but is highly specific for the organs and tissues of the urinary tract. One of its characteristics is its high levels of elasticity which permits it to expand and recoil after stretching. Urothelium consists of nearly 5 cell layers and it also has a thick layer of plaques formed by glycoproteins. Glycoproteins of the urothelium are called uroplakins and participate actively in the maintenance of the integrity of the bladder.
