JACOBSON'S ORGAN

also called Vomeronasal Organ, region of chemically sensitive nerve endings in the oral cavity of many vertebrate animals (amphibians, lizards and snakes, some mammals). The nerve endings are located in a pair of pits that are continuous with the roof of the mouth. Jacobson's organ is most strongly developed in snakes, in which it is employed to supplement weak nasal chemoreceptors in evaluating airborne chemicals. Odours are sampled by flicking out the tongue and retracting it across the Jacobson's organ, where the molecules acquired by the tongue's moist surface are detected.