Molecular Neurogenetics of the Mouse Olfactory System

In the mouse, the sense of smell (olfaction) is mediated by more than 1200 odorant receptors (ORs), the largest gene family in the genome. These ORs are G-protein coupled receptors. Every olfactory sensory neuron (OSN) in the main olfactory epithelium is thought to express just one OR gene, from one allele. Axons of OSNs that express the same OR coalesce into the same structures in the olfactory bulb, termed glomeruli, where they form synapses with second-order neurons in the olfactory pathway.