Diversity of cell-cell interactions formed by gastric parietal cells in culture: morphological study on guinea pig cells.

: Parietal cells of gastric glands are specialized to produce acid. Tight junctions between the parietal cells and their neighbouring cells (usually chief cells and mucous cells, less commonly parietal cells) avoid acid back-diffusion. Alterations of these junctions are accompanied by a defective epithelial barrier function. The conditions leading to junction formation, e.g. during epithelial restitution and regeneration are entirely unknown. The present study has the purpose to establish an in vitro model which allows studying these junctions. Freshly isolated gastric epithelial cells of guinea pig, moderately enriched with parietal cells, were cocultured for 2 days. Highly specific staining techniques showed the following composition in the near-confluent monolayer: 45% parietal cells (succinic dehydrogenase-positive), 36% mucous cells (lectin-binding granules), 18% chief cells (pepsinogen-positive granules) and 1% subepithelial cells (vimentin-positive). Ultrastructural investigations of sections of these monolayers revealed a high tendency of parietal cells to form cell junctions with the following characteristics: 1) virtually all parietal cells formed junctions with their neighbouring cells; 2) only junctions, but no desmosomes, were observed among neighbouring parietal cells; 3) junctional complexes and desmosomes were regularly present between parietal cells and their neighbouring mucous and chief cells; 4) parietal cells were sometimes integrated into three-dimensional structures, resembling rudimentary gastric glands. In conclusion, parietal cells under standard coculture conditions, generate de novo the same types of cell junctions that are observed in the intact gastric epithelium. The results show that parietal cells in vitro spontaneously make junctions with parietal and non-parietal cells, resembling the junctions in the intact tissue.