Since Bensley's ( 1898) classical description of the specialized cell types in the gastric mucosal epithelium much uncertainty has existed concerning their life history. Grant ('45), Stevens and Leblond ('53), Hunt ('57) and Messier ('60) observed that both surface and mucous neck cells arise from the proliferation of cells in the neck region of the fundic gland and are sloughed off, the mucous neck cells at their site of origin and the surface cells after moving to the surface of the mucosa. Hunt ( '57) and Grant ('45) concluded that other cell types in the glands are also lost. Harvey ( '07), Ferguson ('28), and Hunt ('58) implied that parietal and chief cells are replaced by transformation from mucous neck cells but Stevens and Leblond ('53) and Messier ('60) denied the loss and replacement of these cell types. In order to acquire more precise information concerning the origin of the various cell types in fundic glands, numerous investigators have studied their re-appearance in gastric mucosa following surgical or thermal injury to it (Harvey, '07; Ferguson, '28; Gunter, '50; Williams, '53; Hunt, '58; Finckh and Milton, '60). These investigations revealed that (a) the first epithelial cells growing back into an injured area contain mucus and, at least in the newly-formed glands, come to resemble mucous neck cells except for their shape and nuclear structure; and (b) the newlyformed chief and parietal cells seem to arise from these mucus-containing cells. However, conclusive evidence for direct transformation of mucous cells to chief and parietal cells is lacking as is also information concerning the origin of argentophilic cells. Until such evidence is available the sources of these cells cannot be considered proven. Much of the difficulty in visualizing these transformations has arisen from the lack of techniques adequate for the demonstration of transitional forms. The objective of this study was to secure cytological evidence concerning the cellular origin of the chief, parietal and argentophilic cells as they arise in regenerating fundic stomach, utilizing newly modified staining techniques.