Figure 52.3 The Mouse Vomeronasal Organ Identifies Sex (A) The mouse VNO is located adjacent to the nasal passages. It contains pheromone receptors whose input travels to a specific region of the olfactory bulb (the accessory olfactory bulb). Projections from the accessory olfactory bulb go only to areas of the brain involved in sexual behavior, whereas projection from the main olfactory bulb go to many different areas of the brain (not shown). (B) In male mice, information from the VNO is crucial in identifying gender and thus a potential sexual partner.