Research overview: the feline vomeronasal organ

Cats possess a vomeronasal organ, also called the Jacobson's organ, a paired chemosensory structure in the roof of the mouth specialized for detecting pheromones and other chemical signals. This overview surveys its anatomy, including the ducts that connect it to the nasal and oral cavities and the dedicated sensory neurons it contains. The vomeronasal organ operates partly separately from the main olfactory system and is tuned to socially and reproductively important chemicals. The survey relates the organ to the flehmen response, the characteristic open-mouthed grimace by which cats draw scent into it. It frames the vomeronasal organ as a second chemosensory channel complementing ordinary smell. Understanding this structure explains behaviors that puzzle many observers, such as a cat freezing with its mouth open after sniffing a scent mark, and it underlies the cat's sophisticated chemical communication with other cats.