Vomeronasal Chemoreception in Vertebrates: A Study of the Second Nose

The vomeronasal organ is an olfactory structure in the nose, originally described in 1813 by the Danish court veterinarian Ludwig Jacobson. After some 150 years interest in it was reawakened, following the discovery of its key role in social and sexual responses. The organ serves to alert the emotional brain to the presence of specific semiochemicals or signal molecules, which identify sex or status. Typically, such scents elicit responses at a non-conscious level - altering internal chemistry (hormones) in reaction to odours from the social environment (pheromones). The importance of vomerolfaction has recently been confirmed by findings on the genetic basis of smell. This book surveys the biology of the "Organ of Jacobson" from toads to tamarins. It provides an analysis of the neural pathway which processes pheromonal information delivered by the "second nose" to the brain. Vomeronasal olfaction is examined in its evolutionary perspective, from molecular capture of scents to the consequent changes in reproductive activity.