STUDIES OF EXPERIMENTAL COLONIC CANCER INDUCED BY 1, 2-DIMETHYLHYDRAZINE (DMH)

Especially, Emphasis on Sequential Observations by Endoscopy and X-ray

Abstract

Chemical carcinogen, DMH was administered subcutaneously in rats to investigate the incidence and the pattern of development of colonic cancers. The changes of cancers were observed by successive endoscopic and X-ray examinations. The incidence and the development of cancers depended on the period of DMH administration. In the rats administered for 28 weeks, lymphatic metastasis, peritoneal dissemination and liver metastasis were recognized. Sequential endoscopic examinations revealed that the forms of colonic tumors changed from small elevation to flat elevatipn, dome shape, and elevatipn with central depression fainally. As tumors grew, such changes as redness, erosion and hemorrage were frequently found on their surface. The X-ray examination was not so usefull for observation of sequential changes, but relativelly usefull to diagnose extraluminal tumor. It may be concluded that the present study disclosed the incidence and the process of DMH induced colonic cancers.