what is the jacobson's organ
Vomeronasal organ. The vomeronasal organ (VNO), or the Jacobson's organ, is an auxiliary olfactory sense organ that is found in many animals. It lies close to the vomer and nasal bones. It was discovered by Frederik Ruysch prior to 1732 and later by Ludwig Jacobson in 1813. This organ is the sense organ involved in the flehmen response in mammals.