title: The effects of discontinuing administration of high levels of 2-acetylaminofluorene on the transitional epithelium of the mouse urinary bladder.
abstract: The purpose of this study was to investigate the effects of discontinuing the administration of a high level of 2-acetylaminofluorene (2-AAF) on the transitional epithelium of the urinary bladder of BALB/c mice. Mice were fed 500 ppm of 2-AAF for 6 and 13 weeks and sacrificed at periodic intervals after discontinuing the compound. Urothelial hyperplasia regressed slower in the animals receiving the 2-AAF for 13 weeks than those receiving 2-AAF for only 6 weeks. A small number of bladder carcinomas were seen in the animals fed 2-AAF for 13 weeks and sacrificed at 26 and 39 weeks. Our results suggest that exposure to a high level of a carcinogen even for a relatively brief period may result in the development of carcinomas after the cessation of exposure.
mesh_terms: D015073:2-Acetylaminofluorene / Q000494:pharmacology*; D000818:Animals; D002295:Carcinoma, Transitional Cell / Q000139:chemically induced / Q000473:pathology; D004848:Epithelium / Q000187:drug effects; D005449:Fluorenes / Q000494:pharmacology*; D006965:Hyperplasia / Q000139:chemically induced; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D001743:Urinary Bladder / Q000187:drug effects*; D001749:Urinary Bladder Neoplasms / Q000139:chemically induced / Q000473:pathology
chemical_list: D005449:Fluorenes; D015073:2-Acetylaminofluorene