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The preparation of a biological sample using a microtome cryostat was attempted. The biological specimen was previously frozen with a freezing compound and an optimum section thickness was cut for PIXE analysis. First, bovine liver powder which was made into a paste with indium solution as an internal standard was prepared using the sectioning method. The concentrations of trace elements including volatile elements in the sample were determined and agreed with the certified values. Next, a mouse liver was prepared using the sectioning method. A polyphenylene sulfide (PPS) film containing a constant areal density of sulfur was used as a backing material for quantitative analysis. The concentrations of trace elements in a mouse liver prepared using the sectioning method were compared with those using the ordinary nitric acid method. The concentrations of some volatile elements were determined only in the sample obtained using the sectioning method. The preparation method using a microtome cryostat can be used to prepare a biological sample for PIXE analysis.

For the analysis of calcified tissues, nondestructive bioimaging techniques such as X-ray, peripheral quantitative computed tomography (pQCT), and micro-CT are becoming popular to measure their structural architecture and degree of mineralization. However, these techniques do not provide details on the biological changes of tissues. Thus, histology is still an important technique to demonstrate the interaction of mineralized tissue with other soft tissues. A special histological technique known as undecalcified histology or hard tissue histology is used to preserve the calcification information of tissues. Moreover, calcium phosphate-based ceramics has recently been applied in orthopedic research and clinics. Undecalcified histology involving bioceramics is described and discussed, using an experimental rabbit spinal model as an example, to illustrate how to attain good histology.