[Morphological changes of the intervertebral disks of the spine caudal portion in rats after permanent and temporary asymmetric compression-distension].

In the experiment on 44 rats, histological peculiarities of tissue injury and repair were studied in the segments of caudal spine after long-term permanent and temporary (with the subsequent tale relaxation) asymmetric compression-distension (ASCD). Permanent ASCD of the tail was found to result in a complex of structural changes that were rather stable and did not disappear completely after ASCD discontinuation and a long-term relaxation. These changes included necrosis of the annulus fibrosus (AF) cells, tension of AF lamellae and their separation from epiphyses on the distension side, crushing and splitting of AF collagen lamellae on the side of compression and chondrocyte proliferation around necrotic foci, increase of necrotic notochordal cells number in nucleus pulposus (NP). Relaxation after temporary ASCD resulted in the reduction but not total disappearance of the signs of injury. Changes were noted in AF thickness, occurrence of chondrocyte necroses and the sites of collagen lamellae separation, as well as in NP displacement to distension side.