title: Endoscopic study of chronological changes leading to cancer in the esophagus of dogs induced by N-ethyl-N'-nitro-N-nitrosoguanidine.
abstract: An endoscopical study of chronological change during the carcinogenetic process of cancer of the esophagus induced by N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) in 16 male beagle dogs was performed to clarity whether or not precancerous lesions exist in the esophagus. Redness was first observed in the mucosa in the lower and/or middle portions of the esophagus. A small nodule developed in the redness, followed by a nodule. The nodule then developed into a flat polyp which finally developed into lesions such as an elevated lesions, protrusions or elevations with depressions. Histologically, esophagitis or acanthosis in the redness and acanthosis were found in most of the small nodules. With regard to the nodules, papillomatosis was observed in half of the lesions, while either acanthosis or atypical epithelial proliferation were found in most of the flat polyps. Almost all the elevated or protruding lesions were found to be carcinoma.
mesh_terms: D000818:Animals; D001706:Biopsy; D002273:Carcinogens; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced* / Q000473:pathology; D004285:Dogs; D004938:Esophageal Neoplasms / Q000139:chemically induced* / Q000473:pathology; D004945:Esophagoscopy; D004947:Esophagus / Q000473:pathology; D008297:Male; D008769:Methylnitronitrosoguanidine / Q000031:analogs & derivatives* / Q000633:toxicity
chemical_list: D002273:Carcinogens; D008769:Methylnitronitrosoguanidine; C013525:ENNG