Urothelium

When urothelial ( transitional epithelium also ) is called the multi-layered fabric cover (epithelium ) of the urinary tract ( renal pelvis, ureter, urinary bladder, upper part of the urethra ).

Transitional cells are highly prismatic in the unfilled state of the urinary tract, but flat with increasing filling from. By Reserve folds in the cell membrane, a break is possible. Thus they ensure the adaptability of the urinary organs at different filling states.

In the unfilled bladder, the thickness of Urothelschicht is five to six cells. The lowest cells are cuboid, the middle and the top polyhedral have a rounded shape. The bladder is filled, this reduces to three to four cells, the lower cells, and the cuboid surface are flattened.

The surface on the nearest cell having a special membrane, which maintains the osmotic barrier between the urine and the interstitial body fluid. Main component of this membrane are cerebrosides. The urothelium has a certain glycocalix, which is designated in its protein structure Uroplakine. Because urine may also contain toxins and pathogens, it also performs functions in the control of infection and the response to injury.

The superficial cells of the urothelium show a compacted surface appearance in the light microscope differentiation, the crusta.