The innermost tunic, the mucosa, consists of three layers: (1) the mucous epithelium, which is moist stratified squamous epithelium in the mouth, oropharynx, esophagus, and anal canal and simple columnar epithelium in the remainder of the digestive tract; (2) a loose connective tissue called the lamina propria; and (3) a thin smooth muscle layer, the muscularis mucosae.
