Article

Cell and Tissue Research

, Volume 245, Issue 1, pp 9-17

Phagocytosis of different matrix components by different cell types at bone-forming sites in cultured mouse calvariae

  • Tsuneo TakahashiAffiliated withDepartment of Oral Anatomy, Kanagawa Dental College
  • , Seigyo SoAffiliated withDepartment of Oral Anatomy, Kanagawa Dental College
  • , Duenjeng WangAffiliated withDepartment of Oral Anatomy, Kanagawa Dental College
  • , Kazuto TakahashiAffiliated withDepartment of Oral Anatomy, Kanagawa Dental College
  • , Noriyoshi KuriharaAffiliated withDepartment of Oral Anatomy, Josai Dental University
  • , Masayoshi KumegawaAffiliated withDepartment of Oral Anatomy, Josai Dental University

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Summary

Sites of bone formation on fragments of parietal bone of fetal-mice cultured for 10 days were examined by electron microscopy after addition of either ruthenium red or ferrocyanide to the postfixation fluid. Osteoclasts, osteoblast-like cells, and macrophages were the principal active cells at these formation sites. The mononuclear cells (osteoblast-like cells and macrophages) in the osteoid tissue showed evidence of having incorporated elements of calcified tissue. Osteoblast-like cells had phagocytized collagen fibrils and calcified bone matrix. This occurred more frequently in the calcifying area. Mononuclear macrophages showed not only phagocytosis and digestion of cellular debris and bone spicules in the osteoid, but also active incorporation of calcified bone matrix that had been detached from its surroundings by its pseudopod-like projections from long cytoplasmic processes. Collagen fibrils were seldom observed within the macrophages. These observations suggest that in our culture system osteoblast-like cells and macrophages at bone formation sites have a phagocytic role in bone remodeling.

Key words

Calvaria Macrophage Osteoblast-like cell Bone formation Osteoid Mouse