Along with the floor plate, its structure is mediated by the sonic hedgehog gene. Comprised of a group of large cells within a firm connective tissue 
Along with the floor plate, its structure is mediated by the sonic hedgehog gene. Comprised of a group of large cells within a firm connective tissue sheath, the length of its presence can vary in some organisms. Embryonically, it forms during gastrulation between the hypoblast and the epiblast from mesodermal cells, and it is later incorporated as the centers of the nuclei pulposi, or the intervertebral discs. Incompressible and crucial to nervous system development, for 10 points, name this longitudinal rod-like structural element present in all members of the phylum Chordata.
Along with the floor plate, its structure is mediated by the sonic hedgehog gene.
{notochord}