[Studies on the topographic architecture of the annulus fibrosus in developmental and degenerative processes in the lumbar intervertebral disc in man].

Architecture of the annulus fibrosus of the lumbar intervertebral disc in 49 human cadavers (30 fetuses and 19 adults) was observed topographically by polarized light microscopy to investigate the developmental process and the degenerative changes. At the 6th month of fetal life, the anterior annulus fibrosus presented a regular lamellar structure, while the posterior annulus fibrosus presented an irregular reticular structure. Difference of the interstriation angles of collagen fibers in the lamellae between the anterior and posterior annulus fibrosus was identified, and rather smaller angles were found in the anterior than in the posterior. At the 40's years of life collagen fibers in the lamellae showed loosening, separation and a cyst-like cavity, which finally developed into an annular tear. These degenerative changes observed predominantly in the posterior annulus fibrosus suggest that the posterior annulus fibrosus has structural and developmental instability against mechanical stress.