Vomeronasal organ
The vomeronasal organ or Jacobson's organ is an auxiliary olfactory sense organ in some vertebrates, all of which are tetrapods. It is located in the vomer bone, between the nose and the mouth. The sensory neurons within the vomeronasal organ detect distinct chemical compounds, usually large molecules. Snakes use it to smell prey, sticking their tongue out and touching it to the opening to the organ. Some mammals use a distinctive facial movement called flehmen to direct compounds to this organ, while in some other mammals the entire organ contracts or pumps to draw in compounds.Although some scientists believe the vomeronasal organ is specialized for detection of pheromones, some pheromones are detected by the regular olfactory organ, and the vomeronasal organ detects other compounds in addition to pheromones. Thus, its function is still somewhat mysterious.
In humans it is nonfunctional and regresses before birth, as is the case with some other animals, including cetaceans, some bats, and apes. In adult humans there is no neural connection between the organ and the brain.
- See also : Nepetalactone
