<Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> In anatomy, the notochord is a flexible rod made out of a material similar to cartilage . If a species has a notochord at any stage during its life cycle, it is, by definition, a chordate . The notochord lies along the anteroposterior ("head to tail") axis, is usually closer to the dorsal than the ventral surface of the animal, and is composed of cells derived from the mesoderm . The notochord has been observed to have many functions including developmental functions . The most commonly cited functions are as a site of muscle attachment, vertebral precursor, and as a midline tissue that provides signals to the surrounding tissue during development . </P> <P> Notochords are thought to be advantageous (both in an evolutionary and developmental context) because they provide (d) rigid structure for muscle attachment, but were still flexible . In some chordates, it persists throughout life as the main structural support of the body, while in most vertebrates it becomes the nucleus pulposus of the intervertebral disc . The notochord plays a key role in signaling and coordinating development . Embryos of vertebrates still form transient notochord structures today during the gastrulation phase of development . The notochord is found ventral to the neural tube . </P> <P> Notogenesis is the development of the notochord by the epiblasts that make up the floor of the amnion cavity . The progenitor notochord is derived from cells migrating from the primitive node and pit. The notochord forms during gastrulation and soon after induces the formation of the neural plate (neurulation), synchronizing the development of the neural tube . On the ventral aspect of the neural groove an axial thickening of the endoderm takes place . (In bipedal chordates, e.g. humans, this surface is properly referred to as the anterior surface). This thickening appears as a furrow (the chordal furrow) the margins of which anastomose (come into contact), and so convert it into a solid rod of polygonal - shaped cells (the notochord) which is then separated from the endoderm . </P>

What is the fate of notochord in vertebrates