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Excerpt
I read with interest the article by Gruber et al (Analysis of aging and degeneration of the human intervertebral disc: Comparison of surgical specimens with normal controls. Spine;1998;23:751-7).
This is an excellent article that provides additional insight on the degeneration and death of the disc cells. Just recently, we published a similar article1 based on observations taken from a comparative histologic study on blood supply between herniated lumbar vertebrae and intact postmortem spines. Because we believe that the role of disc vascularity is of major importance for death and apoptosis (the word "apoptosis" is Greek and is not written correctly; it should be replaced by the word "ptosis," which means fall, death in English) of the disc cells, we wish to make some important comments to supplement those by Gruber et al. It is recognized that the adult intervertebral disc is avascular by young adulthood, and, after this time, nutrients are presumed to reach disc cells mainly by diffusion. In our study, we found blood vessels invading the disc in the 45% of the surgical specimens and in 75% of the intact disc specimens obtained at autopsy, whereas previous authors1,2 found blood vessels to invade 30-47% of disc specimens. Thus, we concluded that the blood vessels are a concrete sign of degeneration and that ptosis of intervertebral disc cells occurs after the age of 40 years, several years before radiologic signs of degeneration are evident, and that it seems to be linked with some neovascularity within the disc. However, further research on the disc vascularity process on the intracellular level is necessary.
