Light micrograph of urothelial carcinoma in situ (CIS), which is a form of non-invasive bladder cancer. The urothelium is the normal lining layer of cells of the urinary bladder. Urothelial carcinoma is cancer that develops from urothelial cells. The nuclei of urothelial CIS cells are enlarged, hyperchromatic (darker), and have irregular nuclear contours. Compare these features in CIS cells on the left side of the image to normal urothelial cells on the right side of the image. Haematoxylin and eosin stained tissue section. Magnification: 200x when printed at 10cm.