Light micrograph of a section thorough the interior tissue of an anus. The outer layer, or mucosa (top), contains secretory mucous cells (blue). Beneath the mucosa is connective tissue (dark pink) and muscle (bottom). The anus is at the end of the digestive system and is the opening through which faeces are expelled. The mucous helps to lubricate the passage of the faeces. Magnification: x40 when printed at 15cm wide.