Light micrograph of urothelial carcinoma (bladder cancer). The cancer cells occupy most of the field of view with occasional interspersed blood vessels (bright red). The cancer cell nuclei (round blue dots) are pleomorphic (variable in size) with smaller nuclei and some much larger nuclei present. Such variation in nuclear size is a feature of high-grade cancer, which has a greater chance of behaving aggressively by invading locally or metastasis (distant spread). Haematoxylin and eosin stained tissue section. Magnification: x200 when printed at 10x.