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.
What Does Chordata Mean. Chordata have a notochord, a stiff connective tissue rod that runs along the body length, at some point during their development. The notochord is distinct from the vertebral column (backbone) that defines vertebrates. The vertebral bodies form around the notochord, and replace the notochord.