Research Article
Biological Niches within Human Calcified Aortic Valves: Towards Understanding of the Pathological Biomineralization Process
Figure 7
Transmission electron microscopy (TEM) analyses of needle/rod-like pathological crystals. (a, b) Bright field (BF, see Figure 6 for explanation) images and nano-beam electron diffraction (NBD) patterns (in the insets) collected from a calcified bicuspid aortic valve. NBD is a technique that allows determining strain in crystalline materials with a high spatial resolution. A parallel beam with small diameter (~5 nm) is formed in the TEM and scanned across the sample, and diffraction patterns (at a zone axis) are recorded and analyzed for each location. The indices of the diffraction spots indicated in NBD patterns in panels (a) and (b) correspond to interplanar spacings of hydroxylapatite with hexagonal structure (P63/m). The interplanar spacings 002 and 004 are parallel to the elongated form, indicating that nanocrystals elongate parallel to their c-axis.
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