http://en.wikipedia.org/wiki/Notochord
Postembryonic vestige of the notochord is found in the nucleus pulposus of the intervertebral discs. Isolated notochordal remnants may escape their lineage-specific destination in the nucleus pulposus and instead attach to the outer surfaces of the vertebral bodies, from which notochordal cells largely regress.In humans, by the age of 4, all notochord residue is replaced by a population of chondrocyte-like cells of unclear origin.Persistence of notochordal cells within the vertebra may cause a pathologic condition- persistent notochordal canal.They are also found to persist in the nasopharyngeal space and, in such an unusual instance, may give rise to Tornwaldt's cyst.
Postembryonic vestige of the notochord is found in the nucleus pulposus of the intervertebral discs. Isolated notochordal remnants may escape their lineage-specific destination in the nucleus pulposus and instead attach to the outer surfaces of the vertebral bodies, from which notochordal cells largely regress.In humans, by the age of 4, all notochord residue is replaced by a population of chondrocyte-like cells of unclear origin.Persistence of notochordal cells within the vertebra may cause a pathologic condition- persistent notochordal canal.They are also found to persist in the nasopharyngeal space and, in such an unusual instance, may give rise to Tornwaldt's cyst.
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