Aging and degeneration in the lumbar intervertebral disc.

1. The maintenance of the nucleus pulposus matrix in the adult human disc is dependent on the functional integrity of the cartilage end plate cells. 2. Cartilage end plate senescence is followed by compensatory cartilaginous metaplasia of annulus fibrosus cells. 3. It is proposed that disc narrowing and collapse are related to metabolic failure of matrix production by end plate and annulus fibrosus cells. 4. Calcium pyrophosphate dihydrate crystal deposits, a visible manifestation of a metabolic abnormality, are found frequently in the annulus fibrosus and cartilage end plates of elderly patients with degenerative disc disease.