Abstract Histological and histochemical observations reveal that there are two clusters of acidic polysaccharide secreting glands at the opening of the mouth into the oesophagus in Pagurus bernhardus and Clibanarius longitarsus. Below these there are structurally similar glands in the connective tissue of the oesophagus. The epithelial cells lining the hepatopancreatic main duct show secretory activity and they secrete acidophilic granular secretions, which are chemically similar to vertebrate pancreatic zymogen granules. Electron microscopic studies reveal the presence of secretory cells in the hepatopancreatic duct and the synthesis of zymogens within these cells. The time of release of these granular secretions synchronizes with the release of the food material into the midgut.