An auxiliary olfactory sense organ in certain animals and is involved in pheromonic communication and detecting non-volatile chemical cues by direct physical contact with the source of the odor
The vomeronasal organ is an auxiliary olfactory organ that is found in certain animals such as snakes, lizards, and many mammals (e.g. mice, rats, elephants, cattle, dogs, cats, goats, and pigs). Humans lack the vomeronasal organ at the time of birth. That is because it regresses by sixth month of gestation.
The vomeronasal organ is associated with flehmen response, i.e. the drawing back of the lips exposing the front teeth and gums. This response is actually for the animals to inhale with the nostrils and allow the scent to reach the vomeronasal organ. It is believed to be a supplement to the olfactory system and serves as a sense organ for pheromones. It is located on the either side of the nasal septum at the base, near the vomer and nasal bone. It contains sensory neuron and projects to the accessory olfactory bulb.
The vomeronasal organ is also called the organ of Jacobson. This is because this organ is named ater Ludwig Jacobsob, a Danish surgeon. Nevertheless, this organ is first discovered by Frederik Ruysch (a Dutch botanist and anatomist), and then later by Ludwig Jacobson.
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