Question #20
The nucleus pulposus is a remnant of which embryological structure?
The notochord is a signalling centre. It forms in the second week of embryogenesis following gastrulation. It subsequently releases sonic hedgehog which acts on the above ectoderm to induce neural tissue and the formation of the neural tube.
Once the neural tube is formed the notochord has a secondary role setting up dorsal-ventral patterning across the neural tube - again through the actions of sonic hedgehog.
The neural plate is the region of ectoderm above the notochord which is induced to form the neural tube.
The neural tube is the primitive spinal cord.
Neural crest cells are specialised cells that break off from the edges of the neural plate as the neural tube form. They migrate around the body to form a range of different cell types.
Henson's node, also known as the primitive node, is the point where gastrulation begins.