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.
The notochord is oriented head to tail and is found between the digestive tube and the nerve cord. Since it is composed of stiffer tissue, it allows for skeletal support of the organism. In certain chordates, like the lamprey and the sturgeon, the notochord remains there for life.