sentences:  Enterochromaffin-like cells (ECLs), found in the oxyntic glands release histamine, which also is a powerful stimulant of the acid secretion.The A cells produce glucagon, which mobilizes the hepatic glycogen, and the enterochromaffin cells produce serotonin, which stimulates the contraction of the smooth muscles.The surface of the mucous membrane is covered by a single layer of columnar epithelium.