Anorectal junction. Light micrograph (LM) of a section of the transition between rectum (on the left) and anus (on the right). Note the characteristic colonic mucosa with intestinal glands and simple columnar epithelium in the rectum, and the stratified squamous nonkeratinized epithelium of the anus. Magnification: x 150 when printed at 10 centimetres wide. Human tissue.