Abstract
Microspectrophotometric measurement of the DNA content of cell nuclei was performed on the lesions (including atypical glands) in gastric carcinogenesis of 15 male beagle dogs, which had been induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). The distribution patterns of DNA content were classified into three types: normal, subnormal, and abnormal. The histograms of the distribution in normal and regenerative glands were a normal type and subnormal type, respectively, while adenocarcinoma showed an abnormal distribution type. In atypical glands, the distribution patterns in autopsy cases were subnormal and abnormal types. When sequential endoscopic observation of the angulus of the stomach in dog No. 3 was carried out, atypical glands were found in an ulcer in the early stage of MNNG administration and a precancerous lesion in the late stage after termination of MNNG. The atypical glands in the early stage were of the subnormal type, while the atypical glands in the late stage were of the abnormal type. According to the results, these two types-subnormal and abnormal - of distribution of DNA content on the atypical glands may be related to regeneration and subsequent development of cancer, respectively.