Figure 2.

Rat nose-to-brain anatomy. The nose-to-brain anatomy of the rat is similar to the human with a few differences. Compared to the human, the rat nasal cavity has a relatively greater surface area in the olfactory system, making it an ideal animal model for studying IN delivery. The rat nasal cavity consists of the anterior vestibule (dark yellow), respiratory epithelium (yellow), transitional epithelium and olfactory epithelium. Drugs (green arrows) gain access to the brain along the olfactory and trigeminal pathways, similar to human IN delivery.