deoxyribonucleic acid, desoxyribonucleic acid, DNA(noun) (biochemistry) a long linear polymer found in the nucleus of a cell and formed from nucleotides and shaped like a double helix; associated with the transmission of genetic information.
But even adults don't often know what a notochord is. A notochord is a primitive beginning to the backbone. It appears in embryos as a small flexible rod made from cells from the mesoderm, which is one of the three layers of cells of embryos. Notochords are only found in the phylum chordata, a group of animals that includes humans.
In the adult, the notochord is represented by the pulpy centres (nucleus pulposus) of the intervertebral discs. notochord the longitudinal axial support (skeleton) of the embryos of all chordates, which lies ventral to the nerve cord and dorsal to the alimentary canal. Remnants of the notochord usually remain in the adult between the vertebrae, which come to surround it. noÂ·toÂ·chord (nÅ'tÅ-kÅrd)