The mucosal lining of the stomach is simple columnar epithelium with numerous tubular gastric glands. The gastric glands open to the surface of the mucosa through tiny holes called gastric pits. Four different types of cells make up the gastric glands:

• Mucous cells
• Parietal cells
• Chief cells
• Endocrine cells

The secretions of the exocrine gastric glands – composed of the mucous, parietal, and chief cells – make up the gastric juice. The products of the endocrine cells are secreted directly into the bloodstream and are not a part of the gastric juice. The endocrine cells secrete the hormone gastrin, which functions in the regulation of gastric activity.