title: Scanning electron microscopy of colonic lesions in 1,2-dimethylhydrazine-treated rats.
abstract: The surface morphology of late colonic lesions in F344 rats treated with 1,2-dimethylhydrazine was studied by scanning electron microscopy. At week 31 after carcinogen treatment, the surface epithelial characteristics of different types of lesions observed in the colonic mucosa were compared, namely classic elevated aberrant crypt foci (ACF), flat lesion and gross tumour. Classic elevated ACF were easily observed as structures with enlarged crypts elevated from the background mucosa. When the various ACF were compared, or when the ACF were compared with the background mucosa, no ultrastructural differences, or differences in the density of goblet cells were found. The flat lesion showed an epithelium without goblet cells and crypts with small openings harbouring a large number of loose, undefined, dysplastic epithelial cells. These changes appeared to be linked to the malignant development since they were also characteristic of the examined tumour.
authors.affiliation: Department of Food Toxicology, Norwegian Institute of Public Health, 0403 Oslo, Norway. jan.erik.paulsen@fhi.no
authors.forename: Jan Erik
authors.initials: JE
authors.lastname: Paulsen
authors.forename: Ellen
authors.initials: E
authors.lastname: Namork
authors.forename: Jan
authors.initials: J
authors.lastname: Alexander
mesh_terms: D019813:1,2-Dimethylhydrazine; D000818:Animals; D002273:Carcinogens; D003106:Colon / Q000187:drug effects / Q000648:ultrastructure; D003110:Colonic Neoplasms / Q000139:chemically induced* / Q000648:ultrastructure*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000648:ultrastructure; D008297:Male; D008855:Microscopy, Electron, Scanning; D011230:Precancerous Conditions / Q000139:chemically induced / Q000648:ultrastructure; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D002273:Carcinogens; D019813:1,2-Dimethylhydrazine