Comparative study of the morphologic, histochemical, and proliferative changes induced in the large intestine of ICR/Ha and C57BL/Ha mice by 1,2-dimethylhydrazine.
The mouse model of 1,2-dimethylhydrazine (DMH)-induced colorectal carcinogenesis was studied to determine the susceptibility of different anatomic segments of the large intestine in ICR/Ha (susceptible) and C57BL/Ha (resistant) mice. In ICR/Ha mice numerous exophytic macroscopic neoplasms were found in the distal colon and rectum after 15 weekly injections of DMH (20 mg/kg). The proximal colon was free of any microscopic or macroscopic neoplasms. In contrast, C57BL/Ha mice given the same treatment showed no macroscopic neoplasms. However, foci of dysplastic crypts were observed throughout the large intestine of C57BL/Ha mice with highest incidence in the distal colon and rectum. In some areas dysplastic crypts were clearly invading the muscularis mucosae and were, therefore, microscopic carcinomas (microcarcinomas). Thus C57BL/Ha mice were not totally resistant to the neoplastic stimulus of DMH, and the susceptibility of the large intestine is site-specific in both mouse strains.
D019813:1,2-Dimethylhydrazine; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D003110:Colonic Neoplasms / Q000139:chemically induced*; D004127:Dimethylhydrazines / Q000633:toxicity*; D005260:Female; D006651:Histocytochemistry; D007420:Intestine, Large / Q000187:drug effects* / Q000473:pathology; D008297:Male; D008763:Methylhydrazines / Q000633:toxicity*; D051379:Mice; D008815:Mice, Inbred Strains; D009077:Mucins / Q000378:metabolism; D011230:Precancerous Conditions / Q000139:chemically induced*; D012004:Rectal Neoplasms / Q000139:chemically induced*; D052116:Sialomucins
D004127:Dimethylhydrazines; D008763:Methylhydrazines; D009077:Mucins; D052116:Sialomucins; D019813:1,2-Dimethylhydrazine