[Anisotropic crystallization of biominerals].

Bone tissue exhibits an oriented microstructure comprising apatite crystals and collagen fibers. The mechanical, biological and chemical properties of bone tissue represent the highly anisotropic feature depending on the degree of anisotropy in crystallographic structure of apatite. Preferred orientation of apatite crystals is one of the promising parameters which determine bone quality, because the bone mechanical function is dominated by the degree of apatite crystallographic orientation rather than bone mineral density. The anisotropic microstructure of bone tissue is regulated by the mutual activities of bone cells in response to the various kinds of environmental factors. In this report, we introduce the evaluation of bone quality based on the analysis of preferential orientation of apatite c-axis by using micro-beam XRD method and our recent research about cellular regulation of bone tissue anisotropy, especially focusing on the morphological changes of bone cells regulated by the microenvironment surrounding the cells.