Pathology Working Group review of selected upper respiratory tract lesions in rats and mice.

The collected comments and pathologic diagnoses of several pathologists are summarized for 18 cases in which lesions were induced in the upper respiratory tract of rats and mice. Specific neoplastic and nonneoplastic lesions of the nose and trachea are described and discussed, and opinions regarding pathogenesis and biologic significance of the lesions are presented. The anatomic and pathophysiologic complexities of the rodent nose in relation to lesion development following inhalation or systemic exposure to xenobiotics are important considerations in the genesis of pathologic changes in this organ.