1. In rabbit knees the effects of daily injections of saline, Varidase, blood, blood and Varidase simultaneously, and blood alternating with Varidase every third day have been compared. 2. Saline alone produces changes in joint cartilage comparable with a slight damage to the gel structure of the intercellular matrix. 3. The other four experiments resulted in changes in the articular cartilage comparable with the effects of a partial chemical degradation of the polysaccharide of the intercellular matrix. 4. Blood also induced hypertrophy of the synovial tissues. After the end of the injections healing of the cartilage was slower than with saline or with Varidase. 5. When blood and Varidase were given together the immediate effects were additive, but there was a considerable delay in healing.
1. The appearance of decalcified bone matrix in the electron microscope is described. 2. In the matrix two types of collagen fibril have been distinguished. Differences observed are in solubility, x-ray diffraction pattern and appearance. In infant bone the form which appears as fine fibrils predominates. In adult bone the form which appears as tubular fibrils of larger diameter predominates. 3. In bones from elderly subjects the chemical reaction employed to convert collagen into eucollagen sometimes hydrolyses fatty acid esters, and lines due to the free fatty acid are found on the x-ray diffraction patterns of the insoluble residue after citrate extraction. 4. In ancient bones and fossils the stable tubular form of collagen survives, but not the fine fibrils. 5. When decalcified, the matrix in osteoporotic bones loses its architecture and fibrillar form. Under conditions in which only a small fraction is dissolved from normal bone most of the collagen in osteoporotic bone disperses in citric acid. The insoluble residue then gives a modified x-ray diffraction pattern. 6. Evidence has been produced to suggest that the immediate cause of many forms of osteoporosis is some local factor affecting the osteocytes, rather than a general chemical effect.
Throughout this work data have been gathered favouring the concept that the metaphysial vascular arrangement is primarily related to the process of enchondral ossification, and has very limited, if any, responsibility for the nourishment of the growth cartilage. The present evidence favours the suggestion that when the chondrocytes of the column have become too far separated from their source of nourishment (the epiphysial vessels) they and their surrounding matrix suffer changes which prepare them for the process of calcification. At least calcium and phosphate ions will be required for this to take place. The proximity of the vessel and also the fact that it is not isolated by a membrane at its very end suggests a profuse interchange of fluids with the surrounding area.
1. A study of normal and osteoarthritic hyaline cartilage has been made with the electron microscope and x-ray diffraction. 2. Normal cartilage consists of a three-dimensional network of collagen fibrils with no preferred orientation, surrounded by a matrix containing polysaccharide. 3. In the osteoarthritic joint the collagen fibrils show definite orientation and a decreased proportion of ground substance. X-ray diffraction confirms this and shows the orientation to be at right angles to the surface of the femoral head. 4. Tensional forces across the joint may explain why osteoarthritic changes first appear in the non-weight-bearing area of the joint.
