ULTRASTRUCTURAL INVESTIGATION OF LUMBAR INTERVERTEBRAL DISC / 解剖学报

ABSTRACT

The normal lumbar intervertebral discs of rat, rabbit and human (fetal and adult) were studied under transmission electron microscope. In all the specimens the following findings could be observed. The annulus fibrosus was composed of fibrocartilage. However, the cells in the lacunae of the fibrocartilage might show changes in form with the location of the lacunae. The cells in those lacunae on the periphery of the annulus became elongated and lost their scalloped cytoplasmic membrane, thus resembled fibroblasts. On the contrary, the cells in those lacunae in the central portion of the annulus revealed characteristics of the notochordal cells, with pyknosis of nucleus and aggregation of glycogen and fat droplets in the cytoplasm. Consequently the annulus fibrosus exhibited a transition of their cellular components. Elastic fibers could be found in the annulus. Nucleus pulposus contained notochordal cells in a loose matrix. The notochordal cells might exist singly or in clusters and in their cytoplasm there were many vacuoles and aggregates of glycogen and microfilaments.