Common cues wire the spinal cord: Axon guidance molecules in spinal neuron migration

Topographic arrangement of neuronal cell bodies and axonal tracts are crucial for proper wiring of the nervous system. This involves often-coordinated neuronal migration and axon guidance during development. Most neurons migrate from their birthplace to specific topographic coordinates as they adopt the final cell fates and extend axons. The axons follow temporospatial specific guidance cues to reach the appropriate targets. When neuronal or axonal migration or their coordination is disrupted, severe consequences including neurodevelopmental disorders and neurological diseases, can arise. Neuronal and axonal migration shares some molecular mechanisms, as genes originally identified as axon guidance molecules have been increasingly shown to direct both navigation processes. This review focuses on axon guidance pathways that are shown to also direct neuronal migration in the vertebrate spinal cord.