| Research Abstract |
With the recent increase in the number of aged persons, the aging change of joint tissue has become a clinically important problem. From our studies, which have been done over several years, it is recognized that in the joint, the earliest component tissue to suffer aging is the articular cartilage, so it is especially necessary to make clear the mechanism of aging and degenerative process of this tissue. The purpose of this study is to investigate the degenerative findings of the chondrocyte and its surroundings in old aged, and osteoarthritic, and injured cartilagenous tissue respectively, using an electron microscope.
In the cytoplasm of many chondrocytes of old rats, nubecular substances of low electron density, which are considered to be degenerative substances, are observed. Their production may be connected with the rough surfaced endoplasmic reticulum. Sometimes many microtubules, which are considered to increase as one of the aging phenomena, are recognized. In the osteoarthrit
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ic cartilage, cell activity of the chondrocyte seems to go down and some degree of degeneration is found. In the cytoplasm, many and various cell-inclusions, considered to show metabolic abnormality, appear and occupy large parts of the chondrocyte. The size and number of lipid droplets increase, many intracytoplasmic fine filaments lie scattered in a bundle, and lighter stained, degenerated glycogen granules come together in large masses. It is an interesting finding that myeloid bodies with a lamellar structure are often observed and seem to be associated with the mitochondria. Osteoarthritic cartilage shows higher degeneration than aged cartilage of old rats. The problems of injury and repair on the articular cartilage is significant to understand the process of aging. The behavior of cartilage with mechanical injury, especially with partial deficit of this tissue was experimentally observed. From the obtained results, it may suggest the finding of the functional repair of hyaline cartilage by fibrous cartilage. Less
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