CHANGES IN THE SYNOVIAL TISSUES OF THE KNEES OF RABBITS FOLLOWING INTRA- ARTICULAR INJECTION OF THORIUM (THOROTRAST)
Pathologic reactions in the tissues of knees of rabbits following intra- articular introduction of colloidal ThO/sub 2/ (Thorotrast) were studied. Two ml of Thorotrast were injected into each of the right knees of adult male rabbits; in some the right femoral articular cartilages were irritated 24 hr earlier by inserting a needle into the articular cavity and scrntching the anterior surface of the articular cartilage. The animals were killed at intervals of 12, 200, 250, and 270 days following injection of ThO/sub 2/. Macroscopic examination showed collections of the foreign material in the thickened, hypertrophied synovial lining of the injected knees. Lymph glands situated on the lumbar portion of the vertebral column were enlarged and contained ThO/sub 2/ particles. Microscopic examination of tissues removed l2 days after injection revealed ThO/ sub 2/ particles engulfed to the greatest extent by the outer layer of cells of the synovium and by the cells lining the intra-articular tendons. All of the right knee specimens removed after a 200-day interval showed hyperplasia of synovial membrane, with formation of villi. The ThO/sub 2/ particles were situated in clumps, usually engulfed by giant cells, deep in the subsynovial stratum. The outer or surface cells lining of the synovium contained only sparse amounts of foreign material. Collections of ThO/sub 2/ were seen also in subsynovial tissues in the fibers of intra-articular tendons and interstitial loose connective tissue of contiguous muscle fibers. Focal necrosis, calcification, and foreign-body giant cells were encountered in the capsular tissues and in the intraarticular tendon fibers. When articular cartilage was traumatized prior to the injection, ThO/sub 2/ was found in the young reparative connective tissue lining the fibrocartilaginous tissue in the surgically produced defects. Normally, cells in the articular cartilage do not act as macrophages; however, some cells in the contiguous synovial lining did take up some of the foreign substance. The results show that ThO/sub 2/ was rapidly taken up by the outer layer of synovial cells and transported to the subsynovial layer. A hyperplastic and hypertrophic villous type of synovitis was produced, which simulated to some degree the histologic architecture found in nonspecific villous synovitis in man. The newly formed lining cells covering the fibrocartilaginous connective tissue, which appeared in the defects of the femoral articular cartilage, were able to retain the radioopaque and radioactive foreign material, but the original articular cartilage cells did not retain the foreign particles. (BBB)
- Research Organization:
- Hospital for Joint Diseases, New York
- NSA Number:
- NSA-18-017430
- OSTI ID:
- 4060134
- Journal Information:
- Bull. Hosp. Joint Diseases, Vol. Vol: 22; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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