Participation of osteoblast in the osteoclastic resorption of bone in vivo

• Published in: Japanese Journal of Oral Biology Vol. 28; no. 5; pp. 519 - 532
• Main Author: Yamana, Hiromi
• Format: Journal Article
• Language: English
• Published: Japanese Association for Oral Biology 1986
• Subjects: bone resorption; in vivo; Osteoblast; osteoclast; vitamin D3
• ISSN: 0385-0137
• DOI: 10.2330/joralbiosci1965.28.519

Using resorbing calvaria caused by the administration of vitamin D3 to rachitic rats which had been fed a diet low in calcium and deficient in vitamin D3, the morphological changes of osteoblasts in association with the osteoclastic bone resorption were studied in vivo by means of morphometricalas well as biochemical techniques. Within 24 hours after the administration of vitamin D3 to the rachitic rats, the first morphological changes of the bone cells in the calvaria did not occur in osteoclasts but in osteoblasts. Spindle shaped osteoblasts which covered the endosteal surface of the rachitic bone became cuboidal 6 hours after administration of vitamin D3. In the morphometrical study, therefore, active formation surface ratio of the bone increased significantly. At the same time, biochemical la, 25 (OH) 2 vitamin D3 level in the serum increased but neither the mean osteoclasts number nor the serum calcium level was raised at all. The mean osteoclast numbers and the serum calcium level began to rise 12 hours after the administration of vitamin D3 and after 24 hours the mean osteoclast number and the fractional resorption surface ratio increased significantly together with an elevating serum calcium level. After 7 days, with a daily administration of vitamin D3 the osteoclastic bone resorption increased and the endosteal osteoid matrices markedly decreased. These results suggest that the osteoblasts which show early morphological changes might play some important role in association with the osteoclastic bone resorption following the administration of vitamin D3 to rachitic rats.