Fine structure of giant hypertrophic gastritis developed in thymectomized mice.

(C3H/HeMs x 129/J)F1 mice were thymectomized at 3 days of age, and their stomachs were examined by electron microscopy at 3, 6, and 18 months of age. A hypertrophic type of gastritis developed in about half the mice, the fundus being chiefly affected. In the early stage, thickening of the mucosa was attributed mainly to an elongation of the glandular part, but in the later stage it was attributed to both elongated glandular tubules and proliferated foveolar cells. Mature parietal and chief cells were preferentially reduced in number, and immature counterparts were relatively marked in the glandular portion. Thus, the proportion and grade of maturation of these cells in gastritic mice were different from those in normal mice. Foveolar and glandular mucous cells, resembling, respectively, normal surface mucus and mucous neck cells, were the major cell types of the glands. Undifferentiated cells were also frequently encountered. Hyperplasia of endocrine cells, particularly ECL and G cells in the fundic and pyloric mucosa, respectively, was also documented. These results suggest that the gastric hypertrophy of gastritic mice was triggered by the disturbances in differentiation and maturation of parietal and chief cells.