The present study explores biological mechanisms for electric call us formation in terms of immunohistochemical assessment for glycosaminoglycans (chondroitin 4 sulfate, chondroitin 6 sulfate, dermatan sulfate, and keratan sulfate), and S-100 protein α and β during the process of electric callus formation.
On day one after electrical stimulation, the periosteum became considerably thickened and showed two layers. On day two, a sall amount of osteoid tissue was yielded between the electrically stimulated periosteum and the cortex. On day three, the newly formed osteoid tissue progressed to a considerable thickness.
On day five, the osteoid tissue continued to mature. On day seven, the osteid tissue began to calcify and finally formed bone tissue. During this stage, condroidal tissue appeared between the newly formed bone tissue and periosteum. On day nine, calcification of both osteoid and condroidal tissue progressed.
On days 11, 14, and21, this formed bone tissue showed considerable growth as a matured type, and changed to bone trabeculae. Both osteoblasts and osteoclasts existed around the bone tr abeculae.
In the initial stage, periosteum showed moderate staining for glycosaminoglycans, while osteoid tissue showed a strong one. In the stage of matrix calcification, periosteum was stained weakly for proteoglycans, and calcified osteoid tissue showed slight or negative staining for proteoglycans. Cartilage matrix was positive for proteoglycans. The condrochte was strongly stained for keratan sulfate, derumatan sulfate, and condroitin sulfate, and the nucleus was positive for S-100 protein and S-100α.
It is suggested that proliferated mesenchymal cells synthesized proteoglycans that were accum ulated in precalcified osteoid tissue as matrix components. When calcified, the matrix reduced staining intensity for proteoglycans. S-100 protein expression in chondroid tissue suggested that the protein was related to mechanisms of calcium signaling in mineralizing tissue and to calcium regulation for ossification.
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