SUTURAL MINERALIZATION OF RAT CALVARIA CHARACTERIZED BY ATOMIC-FORCE MICROSCOPY AND TRANSMISSION ELECTRON-MICROSCOPY

The application of transmission electron microscopy (TEM) and atomic-f orce microscopy (AFM) aid the acquisition of detailed structural infor mation on the process of hard tissue formation. The sutural mineraliza tion of rat calvaria is taken as a model for a collagen-related minera lization system. After cryofixation or chemical fixation an anhydrous tissue preparation technique with no staining procedures is used. The atomic-force microscope and the transmission electron microscope are u sed for structural analysis of the mineralizing region of the sutural tissue. With the application of AFM the collagen macroperiod is shown to be well represented in the unmineralized sutural tissue. At the min eralization front the collagen fibrils are found to be thickened and t o change to a characteristic stacked platelet structure. Using TEM the macroperiod is faintly visible before mineral crystallites have forme d and is more prominent after the apatite crystallization has started in the fibrils. In this step a needle-like structure of the newly form ed apatitic crystals is visible.