All spinal cord motor neurons derive from a single ventral progenitor domain, located dorso-lateral to floor plate cells. Motor neurons acquire distinct subtype identities, which have been associated with the position of their cell bodies within the spinal cord, together with their axonal projection patterns in the periphery. Motor neuron generally project axons outside the spinal cord and primarily release the acetylcholine neurotransmitter.
Graded Hedgehog and Wnt4/5 signals control the dorsoventral expression of homeodomain transcription factors that specify MMC and HMC fates. In contrast, PGC and LMC neurons are specified by a rostrocaudal FGF signaling gradient that establishes regional domains of Hox transcription factor activity: Hox6 paralogs specify
brachial LMC neurons, Hox9 paralogs specify PGC neurons,
and Hox10 proteins specify lumbar LMC neurons.
Multiple AncestorsSingle AncestorNo DescendantsDevelops fromPart of Parent