Urothelial cells are a specialized type of cell that line the inner surface of the bladder, ureters, and urethra. These cells connect to form a barrier called an epithelium. Transitional epithelium is another name used to describe these cells.
The bladder is an organ which collects, and stores urine produced by the kidneys. Urine travels from the kidneys to the bladder by two tubes called ureters and is leaves the bladder by the urethra. In the bladder, the epithelium is given the special name urothelium. The urothelium is designed to stretch as the bladder fills with urine.
There are several types of cancer that can start from urothelial cells but the most common two types are urothelial carcinoma and papillary carcinoma. If the cancer cells are only seen in the epithelium, the disease is called urothelial carcinoma in situ.