The notochord disappears in birds, but in mammals it is retained in the intervertebral cartilage in the form of a jelly-like inner substance. The Later Development of the Notochord in Mammals. The notochord is found ventral to the neural tube.

The fate of the notochord in mammals has received, in recent years, very scant attention. A notochord is the defining characteristic of members of the phylum Chordata, a large and diverse biological group that includes all animals with spines, or backbones, along with more primitive chordates.The structure has very large cells that are densely arranged within a protective sheath. The notochord ends up as the spinal column (or rather, the area occupied by the notochord is invaded by sclerotome which forms the spinal column).

Between the vertebrae, the notochord does not express type X collagen and is not replaced by bone, but becomes the centre of the intervertebral disc – the nucleus pulposis (Aszodi et al., 1998; Smits and Lefebvre, 2003). The adjacent neural tube becomes the medulla spinalis.

Vestiges of the notochord remain between the vertebrae in fishes and within the vertebrae in amphibians.

Proper knowledge of the development of the human notochord, therefore, is important to understand the pathogenesis of these birth defects. Embryos of modern vertebrates form transient notochord structures during gastrulation. It serves as a source of midline signals that pattern surrounding tissues and as a major skeletal element of the developing embryo. The notochord plays a key role in signaling and coordinating development. Thus, notochord can become ossified in a fashion similar to cartilage. From the Laboratory of Comparative Anatomy, Harvard Medical School.

Wiki User April 27, 2013 6:07AM.

Notogenesis is the development of the notochord … By Leonard W. Williams. The notochord is the defining structure of the chordates, and has essential roles in vertebrate development. it becomes the nucleus pulposus (the jelly like matter) in between the intervertebral discs. What does the notochord become in adult humans? The notochord is a major regulator of embryonic patterning in vertebrates and abnormal notochordal development is associated with a variety of birth defects in man. Notochord definition, a rodlike cord of cells that forms the chief axial supporting structure of the body of the lower chordates, as amphioxus and the cyclostomes, and …

Before all this, the notochord serves serves as some kind of …