Renewal of mouse gastric mucous cells following fast neutron irradiation. An ultrastructural and carbohydrate histochemical study.

Mouse gastric mucosa was studied ultrastructurally and histochemically after exposure to fast neutron irradiation, the number of cells per gastric gland was decreased and the glands were shorter. At day 9, several glands showed a dilated lumen lined by flattened cells. Between days 9 and 16, some of the glands disappeared. Parietal and chief cells disappeared from the remaining glands. At the same time, restoration of the mucosa started. At day 6, proliferative cells were scattered along the isthmus. As in controls, the isthmus contained a few undifferentiated cells many differentiating surface mucous cells (SMC) with developing rough endoplasmic reticulum and silver proteinate-reactive Golgi elements and small secretory granules. At day 9, numerous proliferative cells were clustered in foci. Almost all these cells contained silver proteinate-reactive Golgi elements, granules and vesicles. Most of them were SMC, others mucous neck cells (MNC) or intermediates. At day 16, proliferative foci were larger and consisted of differentiated mucous cells. Regenerated foveolae and glands consisted of large SMC and MNC and a few fibrillovesicular cells. In conclusion, proliferative activity is confined to undifferentiated cells and differentiating mucous cells, which identifies them as the progenitors of the other gastric cell types.