Schematic representation of gastric structure. The stomach is divided into four regions—the cardia, fundus, body, and antrum. The gastric epithelium is coated by a protective layer of mucus seceted by specialized epithelial cells. Gastric pits contain several cell types, including mucus-secreting cells and enteroendocrine cells. The array of cell types found in individual gastric pits varies in different regions of the stomach. H. pylori colonization is largely confined to the antrum, which lacks acid-secreting parietal cells.