Application of the Methylene Blue Staining Method to the Study of Experimentally PNNG-Induced Intestinal Metaplasia of the Canine Stomach

To elucidate the developmental process of the intestinal metaplasia of the stomach, PNNG was orally administered to dogs and the sequential endoscopic examination was performed by using the methylene blue staining method. In the early period of the drug administration dogs showed the findings of erosive gastritis at the antral portion. In the 42nd experimental week, a clearly stained lesion was observed at the gastric angle. The histological findings of the biopsy specimens from the stained lesion showed the elongation of the foveolar epithelium and goblet cell-like mucous cells. Apparently stained lesion was observed at the antral portion in the 128th week. The close-up endoscopic appearance was very similar to that of stained intestinal metaplasia seen in the human stomach. The endoscopic methylene blue staining method as performed in the experimental dogs could provide useful results in the observation of minute lesions especially intestinal metaplasia in human stomach. This experiment, and further studies, may help to elucidate the pathogenesis of the gastric carcinoma in humans.