urothelialtransitonal

Urothelial transitional refers to the urothelium, which is the specialized type of stratified epithelium that lines the urinary tract. This includes the renal pelvis, ureters, bladder, and the proximal part of the urethra. The urothelium is also known as transitional epithelium because its appearance changes depending on the degree of stretch of the organ it lines. When the bladder is empty, the urothelial cells are typically rounded and stratified, appearing somewhat cuboidal or even columnar. As the bladder fills with urine, the epithelium stretches, and the cells flatten, becoming thinner and more squamous in appearance. This remarkable flexibility allows the urinary organs to accommodate varying volumes of fluid without damage.

The urothelium serves multiple functions. Primarily, it acts as a barrier, preventing the potentially irritating and toxic urine from diffusing into the surrounding tissues. It also plays a role in regulating ion and water transport. A key feature of the apical surface of the superficial urothelial cells are specialized membrane proteins called uroplakins, which form plaques that contribute to the impermeability and protective qualities of the urothelium. Alterations in the urothelium can be indicative of various pathological conditions, including infections, inflammation, and cancer, collectively known as urothelial carcinoma. Diagnosis often involves cystoscopy and biopsy.