He or she prepares the tissue and then uses special techniques to examine it under a microscope. They look at the various components of the tissue and describe both normal and abnormal findings. They also grade or stage the tissue. This gives an idea of how far along the tissue was in the degenerative process.
Disc material can be graded using a scale called the Thompson grading system. Based on the amount of degeneration, the disc can receive a grade from I (mild changes) to IV (severe changes). A grade II suggests mild fibrous tissue has infiltrated the center of the disc. The outer covering also shows a mucous-like substance between the cells.
Studies show that crystal deposits also form in the discs. They appear to be age-related, meaning they form more often as we get older. These crystals disrupt the normal cell functions and flow of fluid within the disc. It's likely that they also cause the degenerative process to go faster.