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.
Making the world better, one answer at a time. 1) The notochord is the defining structure of the phylum Chordata, which includes all vertebrates. In its mature state, the notochord is a rod of large cells constrained by a thick extracellular sheath and positioned between the developing spinal cord and gut.o, the notochord and the nerve cord arise from different germ layers. The notochord is replaced by an ossified backbone, though there are still remnants between the vertebrae â¦ . The nerve cord, however, is protected by the ossified vertebral column.