Colon polyps. Light micrograph of a section through the lining of the large intestine (colon) showing polyps (adenomas) due to familial polyposis coli. This inherited disorder causes hundreds of polyps to grow on the lining of the colon. They may cause intestinal bleeding and diarrhoea, and almost always turn cancerous later in life. Treatment of polyposis may require removal of all or part of the colon. The lining of the colon has several layers, including the mucosa or mucous membrane (purple), the submucosa (pink within polyps), and smooth muscle layers (muscularis, pink at bottom). Magnification: x3 when printed 10cm wide.