Spontaneous lesions of the mouse biliary tract.

During the routine histological examination of 2400 aged mice from lifespan carcinogenicity studies a low prevalence of glandular metaplasia of the gall bladder and of the intra-hepatic bile ducts (all associated with cholelithiasis), cholecystitis, cholangitis, papillomatous hyperplasia, papilloma, intra-mural cysts, and focal epithelial ulceration was found. The lesions were found predominantly in female mice and were not treatment related.