成長期ラットの bone cells における運動負荷の影響 : 電子顕微鏡学的検索

抄録

Endochondral ossification in tibial metaphysis was investigated with electronic microscopy using male Wistar rats of four weeks of age, subjected to three kinds of physical exercise, for cellular level study of their effect on longitudinal growth of growing long bones. 1. SEM findings In control group, it is distinctable among the chondral layers such as growing layer, rest layer, hypertrophic layer, erosive layer, and subchondral bone formative layer ; bone formation was mixed with resorption within the trabeculae. Calcified vesicles within the chondral lacunae increased in ascending order of control group, 10 m/min group, 30 m/min group, 40 m/min group ; with vesicles undistinctable. Bone matrix formation was promoted, in trabeculae continuing with subchondral bone formative layer, in ascending order of control group, 30 m/min, 40 m/min group ; the trabeculae were shown thickly and regularly distributed. 2. TEM findings In control group, active osteoblast distributed in single layer or mosaic pattern. The ratio of nucleus and plasma increased, while the organelle decreased in rest osteoblast. A little amount of osteoid was shown between the osteoblast and bone matrix. The young osteocyte in the vicinity of osteoblasts, abundant in organelle, resembling the shape of osteocytes, were shown to be embeded in the organic matrix that was secreted by themselves. The mature osteocytes deep in location, becoming small and lacking in organelle, were surrounded by the lamina limitans with the ratio of nucleus and plasm increased. Cellular network was built up by intercellular connection with plasm processes. Osteoclasts were revealed to absorb bone matrix with ruffled border. The active osteoblasts, osteoblastoid cells and undifferentiated cells and osteocytes in forming stage were shown increased in ascending order of control group, 10 m/min group, 30 m/min group and 40 m/min group. The organellae were shown developed, and mature osteocytes increased in deep location in 40 m/min group. Osteolclasts were shown to get activated in ascending order of control group, 10 m/min group, 30 m/min group, and 40 m/min group. On the basis of the findings mentioned above, the physical exercise facilitated in bone formation of endochandral ossification in metaphysis of tibia.