成長期顎骨における実験的骨粗鬆症に関する研究 : とくに下顎頭の変化

Abstract

Male rats of Wistar strain, three weeks old, were given a calcium-deficient diet and effect of the diet on the mandibular condyle, tibia epiphysis, and tibia metaphysis at growing stage were investigated radiologically and histopathologically. The results were as follows : 1. Radiological findings 1) The mandibular condyle, three weeks after the experiment, became thinner, had uneven and irregular surfaces, and had only a small number of bone trabeculae running disorderedly. Four weeks after the experiment, the mandibular condyle showed no further change in form. However, the surfaces became more uneven and irregular. Five weeks after the experiment, osteolysis was observed on the whole. 2) The tibia epiphysis, three weeks after the experiment, became flat, had uneven and irregular surfaces, and had only a small number of bone trabeculae running disorderedly. Four weeks after the experiment, cystic defect and osteolysis were seen. Five weeks after the experiment, the tibia epiphysis deformed further, and the state of uneven and irregular surfaces and disorderly running of bone trabeculae were observed. 3) The tibia metaphysis, three weeks after the experiment, showed disorderly bone structure and was indistinct in morphology. Four weeks after the experiment, osteolysis was also seen along the line of the tibia metaphysis and the surfaces were napped. Five weeks after the experiment, the line of the tibia metaphysis was depressed toward the tibia metaphysis and showed the state of cupping. 2. Histopathologlcal findings 1) In the mandibular condyle, three weeks after the experiment, the cartilage layer thickened due to the expanded zone of hypertrophic chondrocytes. Calcified matrix surrounding hypertrophic chondrocytes and chondroclasts in the zone of erosion decreased. Four weeks after the experiment, hypertrophic chondrocytes decreased slightly. Calcified matrix, chondroclasts, and bone formation decreased further. Five weeks after the experiment, the zone of hypertrophic chodrocytes expanded and the arrangement of chondrocytes was disordered further. Hypertrophic chondrocytes deformed and bone trabeculae were thin and sparesly arranged. 2) In the tibia epiphysis, three weeks after the experiment, the zone of hypertrophic chondrocytes expanded. Calcified matrix surrounding hypertrophic chondrocytes, chondroclasts in the zone of erosion, and bone formation decreased. Four weeks after the experiment, hypertrophic chondrocytes increased further. Deformation, disorderly arrangement, and clustering of chondrocytes were observed. Five weeks after the experiment, the zone of hypertrophic chodrocytes expanded further. Bone trabeculae were small in number and thin. 3) In the tibia metaphysis, three weeks after the experiment, the zone of hypertrophic chondrocytes expanded. Calcified matrix and chondroclasts in the columnar interspaces of hypertrophic chondrocytes were few. Bone formation was scarcely seen. Four weeks after the experiment, the chondrocyte layer was decreased slightly and chondrocytes were smaller. Columnar arrangement of chondrocytes was reduced and congregated. Five weeks after the experiment, hypertrophic chondrocytes increased again and arrangement of chondrocytes was disordered further. Bone formation in cartilages was not observed at all and bone trabeculae were small in number and thin. 3. On the basis of the foregoing findings, osteporosis induced by calcium-deficient diet was the severest in changes at the tibia metaphysis. Especially, increase and decrease in chondrocytes, morphological reduction, decrease in chondroclasts in the cartilage, and disturbance in bone formation were observed. These changes were more marked than those in the mandibular condyle and tibia epiphysis. Changes in the tibia epiphysis were greater than those in the mandibular condyle.