The Infantile nucleus pulposus is occupied by tissue derived from the notochord. The nucleus pulposus of this type is replaced by a different type of nucleus pulposus, composed of fibrocartllage and dense fibrous tissue at the first half of the second decade. In the adult, the nucleus pulposus shows morphologically high cell activities near the cartilaginous end-plate, including a process suggestive of regeneration. The surface layer of the cartilaginous end-plate and adjacent layer of the nucleus pulposus seems to play an Important role in the maintenance of the nucleus pulposus. Both the calcification within the cartilaginous end-plate, accompanied by bone formation, and Its superficial detachment, seems to destroy this layer and lead up to the obliteration of the disc.
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