title: Age-dependent odontogenic lesions in rats after a single i.p. injection of N-nitroso-N-methylurea.
abstract: The development of a variety of odontogenic lesions was elicited by a single i.p. injection of N-nitroso-N-methylurea (NMU) at a dose of 150 mg/kg body weight. A total of 190 male Wistar/Furth rats were used in this study. The odontogenic lesions appeared macroscopically, mainly as supernumerary lower incisors, 88 +/- 3.48 (SE) days after administration of the carcinogen. Tumors were classified as compound and complex odontomas, odontoameloblastomas and ameloblastomas. 72% of rats (31 out of 43) 6 weeks old at the time of inoculation developed microscopic alterations in the odontogenic organs of the incisors; only 4% (2 of 49) of rats injected at 8 weeks of age developed similar alterations. These findings suggest the presence of an ontogenic mechanism susceptible to damage by chemical carcinogens.
mesh_terms: D000818:Animals; D003804:Dentin / Q000187:drug effects / Q000473:pathology*; D007180:Incisor / Q000187:drug effects / Q000473:pathology*; D008297:Male; D008770:Methylnitrosourea / Q000633:toxicity*; D009374:Neoplasms, Experimental / Q000473:pathology; D009607:Nitrosourea Compounds / Q000633:toxicity*; D009808:Odontogenic Tumors / Q000139:chemically induced* / Q000473:pathology; D009810:Odontoma / Q000139:chemically induced* / Q000473:pathology; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
chemical_list: D009607:Nitrosourea Compounds; D008770:Methylnitrosourea