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.
notochord /noÂ·toÂ·chord/ (nÅtÂ´o-kord) a rod-shaped cord of cells on the dorsal aspect of an embryo, defining the primitive axis of the body and serving as the center of development of the axial skeleton; it is the common factor of all chordates. notochord (nÅâ²tÉ-kÃ´rdâ²)