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A specialized part of the olfactory system located anteriorly in the nasal cavity within the nasal septum. Chemosensitive cells of the vomeronasal organ project via the vomeronasal nerve to the accessory olfactory bulb. The primary function of this organ appears to be in sensing pheromones which regulate reproductive and other social behaviors. While the structure has been thought absent in higher primate adults, data now suggests it may be present in adult humans.