Colon cancer. Coloured scanning electron micrograph (SEM) of a freeze-fractured section through blood vessels in a cancerous colon (large intestine). Many erythrocytes (red blood cells, red) are seen. Numerous blood vessels exist in the sub-mucosal layer of the colon, supplying blood to receive the nutrients absorbed during digestion. Increased blood supply is also seen around cancer sites. In addition, one of the symptoms of colon cancer is faecal blood. Colon cancer is one of the most common cancers in the developed world. Treatment involves surgery and chemotherapy. Magnification: x500 at 6x7cm size.