A cell found throughout the gastrointestinal tract and in the pancreas. They secrete somatostatin in both an endocrine and paracrine manner. Somatostatin inhibits gastrin, cholecystokinin, insulin, glucagon, pancreatic enzymes, and gastric hydrochloric acid. A variety of substances which inhibit gastric acid secretion (vasoactive intestinal peptide, calcitonin gene-related peptide, cholecystokinin, beta-adrenergic agonists, and gastric inhibitory peptide) are thought to act by releasing somatostatin. [ MESH:D019864 ]