What is the definition or description of: nucleus pulposus?

The center part of a: Disc. There is an outer fibrous part known as the annulus fibrosis that is very tough and made of multiple layers containing a more elastic central core known as the nucleus pulposus which is mostly water when young and gets less elastic with age as it loses water content.

Part of a disc: The intervertbral disc hasteo parts the annulus outside tough ring and the nucleus pulposus the central gelatinous portion the part that squirts past the retaining ring to push on nerveshnp herniated nucleus pulposus disc herniation.