From the internal surface to the external surface, the digestive tube wall is made of mucosa (epithelial tissue responsible for the intestinal absorption), submucosa (connective tissue beneath the mucous membrane and where blood and lymphatic vessels and neural fibers are located), muscle layers (smooth muscle tissue, two layers, one interior circular and other exterior longitudinal, structures responsible for the peristaltic movement), serous membrane (associated epithelial and connective tissue forming the external surface of the organ). In the bowels the serous membrane prolongs to form the mesentery, a serosa that encloses blood vessels and supports the bowels within the abdominal cavity. Digestion System - Image Diversity: histology of the digestive tube