uroepiteelin

Uroepiteelin, also known as urothelium, is a specialized type of transitional epithelium that lines the urinary tract. It is found in the renal pelvis, ureters, urinary bladder, and the proximal part of the urethra. This tissue is characterized by its ability to undergo significant changes in shape, expanding and contracting to accommodate varying volumes of urine. The urothelium's unique structure plays a crucial role in preventing the reabsorption of water and electrolytes from the urine and protecting the underlying tissues from the cytotoxic effects of urine components.

The cells of the uroepiteelin are arranged in multiple layers. The superficial cells, known as umbrella cells or facet cells, are particularly distinctive. They are large, dome-shaped, and possess a unique apical membrane rich in specialized plaques. These plaques contain proteins like uroplakins, which contribute to the impermeability of the urothelium and its resistance to osmotic stress and chemical irritation. Beneath the umbrella cells are intermediate cells, and the deepest layer consists of basal cells, which are responsible for the regenerative capacity of the urothelium.

The uroepiteelin serves several vital functions. Its primary role is to act as a barrier, preventing the leakage of urine into the surrounding tissues. This barrier function is essential for maintaining the body's fluid balance and preventing infection. Additionally, the urothelium plays a role in immune surveillance and can contribute to the production of signaling molecules that influence bladder function and the immune response. Disorders affecting the uroepiteelin, such as urothelial carcinoma (bladder cancer), can have serious health implications.