Histopathologic examination of the rat nasal cavity.

A method for preparation of the rat nasal cavity for histopathologic examination is presented, and the anatomic features of the sections obtained are described. The method results in four tissue sections which are selected because of their reproducibility based on landmarks on the dorsal aspect of the mouth and because of the anatomic features of each section which contribute to a thorough examination of the nasal cavity. The four areas examined include transverse sections taken at the following points: (1) immediately posterior to the upper incisor teeth, (2) at the incisive papilla, (3) at the second palatal ridge, and (4) at the level of the first upper molar teeth. The value of each section to the overall evaluation of the nasal cavity and adjacent structures is also discussed. The method described is applicable to both short-term and chronic toxicity studies, and allows for a thorough examination of the nasal cavity without destructive invasion at the time of necropsy.