Evaluation of the rabbit nasal cavity in inhalation studies and a comparison with other common laboratory species and man.

The rabbit is occasionally used for inhalation and intranasal safety assessment studies, but there are no detailed descriptions of the anatomy or histology of the rabbit nose. To address this deficit, the nasal cavities of thirty-two control adult rabbits were sectioned and examined to provide mapping of the main epithelial types and histological structures present within the cavity and turbinates. Four levels of the nasal cavity were prepared and examined using anatomic landmarks. Level I was sectioned immediately posterior to the incisors, Level II at the first palatal ridge, Level III immediately anterior to the first upper premolar teeth, and Level IV immediately anterior to the first upper molar. Level I was lined predominantly by squamous epithelium with small amounts of thick transitional epithelium, and examination is recommended only for studies involving test article administration via instillation. Level II was lined primarily with transitional and respiratory epithelia, whereas Levels III and IV were lined with respiratory and olfactory epithelia and often contained nasal-associated lymphoid tissue. The vomeronasal organs were evident only in Level II. The similarities and differences of these features are compared with those of other common laboratory species (rat, mouse, dog, and cynomolgus monkey) and man.