Peptic cells.

Immunocytochemical studies have demonstrated the existence of five different types of peptic cells in man. These are chief and mucus neck cells in fundic gland mucosa, the pyloric glands in antral mucosa, and the cardiac and Brunner's glands. There are two immunochemically distinct groups of pepsinogens, pepsinogen group I (PG I) and pepsinogen group II (PG II). Chief cells and mucous neck cells in fundic gland mucosa contain both PG I and PG II. Cardiac gland cells, pyloric gland cells and cells in Brunner's glands are clear staining (with hematoxylin and eosin) and usually contain only PG II. On occasion, faint positivity with PGI antiserum may be found in clear staining pyloric gland cells. Gastric gland heterotopia and metaplasia of fundic or pyloric type may be found anywhere in the gastrointestinal tract, but most often in the distal esophagus and duodenal bulb. Heterotopic and metaplastic gastric cells contain pepsinogens similar to the normal peptic cells in the stomach: chief-type cells contain both PG I and PG II, and clear staining cells only PG II. In the presence of hydrochloric acid, the production of pepsinogens may cause local peptic digestion outside of the stomach.