notochord /nō″tōkôrd/ [Gk, noton, back, chorde, cord] , an elongated strip of mesodermal tissue that originates from the primitive node and extends along the dorsal surface of the developing embryo beneath the neural tube, forming the primary longitudinal skeletal axis of the body of all chordates. In humans and other higher vertebrates, the structure is replaced by vertebrae, although a remnant of it remains as part of the nucleus pulposus of the intervertebral disks. See also neural tube. −notochordal, adj.
