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.
免疫细胞化学研究已证实在人类中存在五种不同类型的消化细胞。这些细胞存在于胃底腺黏膜中的主细胞和黏液颈细胞、胃窦黏膜中的幽门腺以及贲门腺和布伦纳腺。有两组免疫化学性质不同的胃蛋白酶原，即胃蛋白酶原I组（PG I）和胃蛋白酶原II组（PG II）。胃底腺黏膜中的主细胞和黏液颈细胞同时含有PG I和PG II。贲门腺细胞、幽门腺细胞和布伦纳腺中的细胞染色清晰（苏木精和伊红染色），通常仅含有PG II。偶尔，在染色清晰的幽门腺细胞中可能会发现对PGI抗血清的弱阳性。胃腺异位和胃底型或幽门型化生可出现在胃肠道的任何部位，但最常见于食管远端和十二指肠球部。异位和化生的胃细胞含有与胃中正常消化细胞相似的胃蛋白酶原：主细胞型细胞同时含有PG I和PG II，而染色清晰的细胞仅含有PG II。在盐酸存在的情况下，胃蛋白酶原的产生可能会导致胃外的局部消化。
