vomeronasal

Vomeronasal refers to the vomeronasal system or organ, a chemosensory subsystem used by many vertebrates to detect pheromones and related chemical cues. The key anatomical component is the vomeronasal organ (VNO), a paired tubular organ located at the base of the nasal cavity, near the vomer bone. In mammals, the VNO connects to the accessory olfactory bulb, a neural structure distinct from the main olfactory bulb. The sensory neurons of the VNO express vomeronasal receptors, primarily the V1R and V2R gene families, which detect a range of non-volatile chemical signals. Signal transduction in VNO neurons involves G protein-coupled receptors, typically G alpha i2 in V1R-expressing cells and G alpha o in V2R-expressing cells, leading to depolarization and neurotransmitter release.

Functionally, the VNO is implicated in social and reproductive behaviors, including mate choice, territory marking, aggression, and maternal bonding in species where it is functional. Because many pheromones are non-volatile and require close contact, the VNO is well suited to detecting cues that do not reach the main olfactory system. The VNO projects to the accessory olfactory bulb, which in turn interfaces with limbic regions such as the amygdala and hypothalamus to influence behavior and hormonal responses.

In humans and some primates, the vomeronasal organ is largely vestigial and its function is debated; genetic and anatomical evidence suggests reduced receptor repertoires and limited functionality. Across many vertebrates, the VNO remains a key component of chemical communication.