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. Tigh t junctions between the parietal cells and their neighbouring cells (u sually chief cells and mucous cells, less commonly parietal cells) avo id 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 regenerati on are entirely unknown. The present study has the purpose to establis h an in vitro model which allows studying these junctions. Freshly iso lated 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 mono layer: 45% parietal cells (succinic dehydrogenase-positive), 36% mucou s cells (lectin-binding granules), 18% chief cells (pepsinogen-positiv e granules) and 1% subepithelial cells (vimentin-positive). Ultrastruc tural investigations of sections of these monolayers revealed a high t endency of parietal cells to form cell junctions with the following ch aracteristics: 1) virtually all parietal cells formed junctions with t heir neighboring cells; 2) only junctions, but no desmosomes, were obs erved among neighboring parietal cells; 3) junctional complexes and de smosomes were regularly present between parietal cells and their neigh boring mucous and chief cells; 4) parietal cells were sometimes integr ated into three-dimensional structures, resembling rudimentary gastric glands. In conclusion, parietal cells under standard coculture condit ions, generate de novo the same types of cell junctions that are obser ved in the intact gastric epithelium. The results show that parietal c ells in vitro spontaneously make junctions with parietal and non-parie tal cells, resembling the junctions in the intact tissue.