Between the chief cells and the basement membrane, larger oval cells, which stain deeply with eosin, are found; these cells are studded throughout the tube at intervals, giving it a beaded or varicose appearance. These are known as the parietal cells or oxyntic cells, and they are connected with the lumen by fine channels which run into their substance.
At the point where they open into the duct, which is termed the neck, the epithelium alters, and consists of short columnar or polyhedral, granular cells, which almost fill the tube, so that the lumen becomes suddenly constricted and is continued down as a very fine channel. They are known as the chief cells or central cells of the glands.
G cells are a type of enteroendocrine cell that secrete the hormone gastrin (gastrin promotes the secretion of pepsinogen (by chief cells) and HCl (by parietal cells) and promotes gastric contractions to mix contents).