Incidence of Respiratory Metaplasia of the Nasal Gland Epithelium in Untreated F344 Rats and BDF1 Mice Subjected to Two-Year Carcinogenicity Studies

Abstract

The incidence, distribution, and histopathology of respiratory metaplasia of the nasal gland epithelium were examined in F344 rats and BDF1 mice used as untreated control animals in 2-year carcinogenicity studies. Lesions were detected in almost all the male and female rats, while they were only detected in 67.8% and 46.6% of the male and female mice, respectively. In rats, most lesions were located in the septal and/or nasoturbinate subepithelial glands at the incisive papilla level, whereas the lesions varied in location and were histopathologically more severe in mice.