No susceptibility of colon tissue implanted into the glandular stomach of rats to N-nitroso-N-methylurea carcinogenesis.

The present study was undertaken to determine the response of colonic mucosa implanted into the stomach fundus in 6-week-old male F344 rats to oral administration of N-nitroso-N-methylurea (MNU). In graft + MNU, 15% animals had tumors in the implanted colon tissue whereas a 26% incidence of gastric tumors was observed for the pyloric mucosa. In MNU alone, 30% of rats demonstrated gastric tumors. In graft alone 10% of tumors were observed in the grafted site but none in the pylorus. Thus while graft tissue may intrinsically have an elevated risk of tumor development, no susceptibility to MNU was observed in the present study.