Olfactory Subsystems in Mammals: Specific Roles in Recognizing Chemical Signals?

Abstract

Animals survey their external environment for relevant chemicals including compounds which are important for finding food sources and habitats but also for social interaction and reproduction. In mammals, these chemical signals are received by divergent chemosensory subsystems: the main olfactory epithelium which is considered to be responsible for the reception of general odorants, the vomeronasal organ (VNO) which is thought to mediate the detection of substances carrying specific information concerning species, gender and identity of an animal, and a small epithelial patch on the nasal septum at the entrance to the nasopharynx called the septal organ (SO), which by virtue of its exposed position in the respiratory air stream, has been proposed to play an alerting role (Figure 1).