Electron microscopic study of the repair of aspirin-induced gastric erosions.

To investigate the fine-structural events occurring during repair of aspirin-induced erosions, rats were killed at times from 2 to 48 hrs after a single aspirin dose. Erosions were rapidly covered by a line of flattened cells with little evidence of cytoplasmic specialization. Some of these cells lining early erosions contained a few mucous granules, but none showed features to suggest a derivation from parietal or zymogen cells. By 24-48 hr, considerable differentiation had accurred in the repairing epithelium, with many cells containing mucous granules and with "young" parietal cells being abundant. Some epithelial cells contained erythrocyte fragments, thus demonstrating phagocytic capability. It is concluded that dedifferentiation of surviving gastric epithelial cells occurs rapidly in response to aspirin injury and that the mucoid cells, rather than specialized glandular cells, are the likely source of the initial repair epithelium.