Light micrograph of benign urothelium. Urothelium is composed of urothelial cells. The urothelial cell nuclei (dark blue) are oval to round and contain grooves (small thin lines). The cells are arranged roughly in parallel to each other and perpendicular to the basement membrane (horizontal). The top layer of urothelium consists of large umbrella cells, which each covers 2-3 of the urothelial cells below. Haematoxylin and eosin stained tissue section. Magnification: 400x when printed at 10 centimetres.