Electron microscopic study of the morphological changes of gastric mucous cell induced by Helicobacter pylori in human gastric ulcers.

Specimens from 8 cases of human gastric ulcers infected with H. pylori, 3 cases of gastric ulcers without H. pylori infection and mucosal specimens infected with H. pylori from 3 cases of early gastric cancers obtained at surgery were studied by transmission electron microscopy. In the surrounding epithelium of the ulcer, when present, the bacteria were preferentially located at the luminal side of the apical junctional complexes. This was accompanied by dome-like bulging of the apical cytoplasm, but the epithelial continuity was maintained. A consistent finding was the apocrine-like release of the apical cytoplasm into the lumen. In addition, there were cells with marked apical protrusions and cells with dissolution of mucous granules. Degenerative changes, such as cellular edema, vacuole formation and disruption of cell membrane were also observed. The cells which had shed their apical mucous area appeared to degenerate causing massive cell exfoliation and formation of denuded lamina propria. Similar changes of the surface mucous cells were observed in the mucosal specimens infected with H. pylori obtained from early gastric cancers, but such cell pathology was scarce in samples of the gastric ulcers without H. pylori infection. In some ulcers infected with H. pylori, the bacteria were also observed on the surface of the regenerating epithelial cells at the ulcer base. These findings suggest that H. pylori infection is an important factor in the development of gastric ulcers and in the prevention or delay in ulcer healing.