The Deifinition and Origin of a Notochord

A notochord is often described as a primitive backbone. The word notochord comes from the Greek words notos (back) and chorde (cord). It is a rigid, cartilaginous rod that is present at some stage of development in all chordates. Some organisms, like African lungfish, tadpoles, and sturgeon, retain a post-embryonic notochord. The notochord is formed during gastrulation (an early phase in the development of most animals) and lies along the axis from the head to the tail. Notochord research has played an important role in scientists' understanding the development of animals' central nervous system. 

Notochord Structure

Notochords provide a rigid, yet flexible structure that enables muscle attachment, which is believed to be advantageous both for individual development and evolution. It is made from a material that is similar to cartilage, the tissue you find at the tip of your nose and a shark's cartilaginous skeleton.

Notochord Development

The development of the notochord is known as notogenesis. In some chordates, the notochord is present as a rod of cells that lies beneath and parallel the nerve cord, giving it support. Some animals, like tunicates or sea squirts, have a notochord during their larval stage. In vertebrates, the notochord is typically present only in the embryo stage.