False-colour scanning electron micrograph (SEM) of the mucous membrane lining the stomach, showing the entrance to a gastric gland. The stomach glands produce hydrochloric acid, mucous, digestive enzymes (pepsin) & hormones, substances derived from the simple columnar cells that comprise the moss-like mucous membrane (mucosa). Gastric glands are formed by simple invagination or tubular ingrowth of this mucosa into the underlying layer. The secretion of mucous serves to protect the epithelium from digestion by the other secretory products. Magnification: x720 at 6x7cm size.