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The notochord is derived from the embryonic mesoderm and consists of an inner core of vacuolated cells filled with glycoproteins, covered by two helical collagen-elastin sheaths. It lies longitudinally along the rostral-caudal (head to tail) axis of the body, dorsal to the gut tube, and ventral to the dorsal nerve cord.
In this way the notochord can be characterized as a hydrostatic organ. [1] During muscle contraction, the notochord also plays an important role in withstanding shortening of the body. [10] The dorsal nerve cord is located behind the notochord. The pharynx is another structure made from cartilage for feeding, found near the throat.
The dorsal nerve cord is an anatomical feature found in chordate animals, mainly in the subphyla Vertebrata and Cephalochordata, as well as in some hemichordates.It is one of the five embryonic features unique to all chordates, the other four being a notochord, a post-anal tail, an endostyle, and pharyngeal slits.
Cells in this area, known as medial hinge point cells because of their involvement with this structure, are stabilized and connected to the notochord. They are derived from the area of the neural plate anterior to primitive knot. The notochord will begin the shape changes in MHP cells. These cells will decrease in height and become wedge-shaped.
The notochord disappears in the sclerotome (vertebral body) segments but persists in the region of the intervertebral discs as the nucleus pulposus. The nucleus pulposus and the fibers of the anulus fibrosus make up the intervertebral disc. The primary curves (thoracic and sacral curvatures) form during fetal development.
Homeobox protein notochord (NOTO) is a transcription factor [1] encoded by the gene notochord homeobox (NOTO) located on the short arm of chromosome 2 (2p13.2) in humans (Homo sapiens). [2] An ortholog of NOTO is found in the house mouse ( Mus musculus ), among other species, as the gene notochord homeobox ( Noto ) located on chromosome 6 ...
This forms the notochord, which induces the formation of the neural tube, and establishes the anterior-posterior body axis. The notochord extends beneath the neural tube from the head to the tail. The mesoderm moves to the midline until it covers the notochord. When the mesoderm cells proliferate, they form the paraxial mesoderm.
The notochord extends from the base of the head to the tail; with it extend thick bands of paraxial mesoderm. [ 3 ] As the primitive streak continues to regress, somites form from the paraxial mesoderm by "budding off" rostrally.