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This study was carried out to determine the effect of age on the intervertebral disc, using a rabbit model. Anulus fibrosus and nucleus pulposus tissue from New Zealand white rabbits aged 3 years old (old rabbits) and 6 months old (young rabbits) were used. The water content, the proteoglycan, the DNA content, and the mRNA levels of aggrecan, type I collagen, and type II collagen were all measured for each sample. Water, proteoglycan, DNA, and the mRNA levels of aggrecan and type II collagen were all greater in the nucleus pulposus of the young rabbits as compared to the old. For the anulus fibrosus, the difference between young and old is less marked with only proteoglycan and DNA being greater in the young disc as compared to the old. Clearly, according to our results, it is the nucleus pulposus that suffers the brunt of the changes with age. [ABSTRACT FROM AUTHOR]

STUDY DESIGN.: Histological observational study of patients with spinal meningioma. OBJECTIVE.: To clarify the status of tumor cell invasion into the dura mater and to provide fundamental information for appropriate management of dural attachment. SUMMARY OF BACKGROUND DATA.: Histological appearance of the dura attached to spinal meningioma has not been sufficiently evaluated. METHODS.: Dura mater resected in a Simpson Grade 1 manner from 25 consecutive patients with spinal meningiomas (World Health Organization grade 1) was histologically observed to determine the status of tumor cell invasion. As no clear borders such as a tumor capsule between tumor and dura mater were observed, histological findings of the dura mater were classified into the following 3 categories: grade 1, no dural invasion, with only inflammation of the dura; grade 2: dural invasion below the zone between the inner and outer layers; and grade 3, dural invasion into or over the zone between the inner and outer layers (full-thickness invasion). RESULTS.: In our microscopic study, 19 of the 25 cases of spinal meningioma showed evidence of dural invasion and 15 cases showed full-thickness invasion. CONCLUSION.: This histological investigation of resected dura mater attached to spinal meningioma showed a high rate of full-thickness tumor invasion into the dura mater. [ABSTRACT FROM AUTHOR]