A term devised by Richard Owen (1804-1892) in 1848, it is an axial mesodermal tissue, adjacent to the neural tube, found in embryonic stages of all chordates and protochordates, and which often regresses as maturity is approached. Typically, it is a rod-shaped mass of vacuolated cells, lying immediately below the nerve cord and may provide mechanical support to the embryo as well as a role in specifying regional activity in the central nervous system.
See Dermomytome, Embryogenesis, Gastrulation, Hensen’s node, Mesoderm, Neural plate, Neural tube, Neurulation