- 1. In primitive vertebrates, the primary axial supporting structure of the body, derived from the notochordal or head process of the early embryo; an important organizer for determining the final form of the nervous system and related structures. 2. In embryos, the axial fibrocellular cord about which the vertebral primordia develop; vestiges of it persist in the adult as the nuclei pulposi of the intervertebral discs. SYN: chorda dorsalis. [G. notos, back, + chorde, cord, string]
* * *no·to·chord 'nōt-ə-.kȯ(ə)rd n a longitudinal flexible rod of cells that in the lowest chordates (as a lancelet or a lamprey) and in the embryos of the higher vertebrates forms the supporting axis of the body, that is almost obliterated in the adult of the higher vertebrates as the bodies of the vertebrae develop, and that arises as an outgrowth from the dorsal lip of the blastopore extending forward between epiblast and hypoblast in the middorsal lineno·to·chord·al .nōt-ə-'kȯrd-əl adj
* * *n.a strip of mesodermal tissue that develops along the dorsal surface of the early embryo, beneath the neural tube. It becomes almost entirely obliterated by the development of the vertebrae, persisting only as part of the intervertebral discs.
* * *no·to·chord (noґto-kord) [noto- + chord] the rod-shaped body, composed of cells derived from the mesoblast of the primitive node of the embryo, defining the primitive axis of the body and acting as the center of development of the axial skeleton; it is the common factor of all species of the phylum Chordata. Called also chorda dorsalis.
Medical dictionary. 2011.