Biological Niches within Human Calcified Aortic Valves: Towards Understanding of the Pathological Biomineralization Process

Figure 2

Scanning electron microscopy (SEM) micrographs of niches within human heart valve tissue. (a) Starting from a micrometer scale, within the niches we observed bioapatite deposits in different crystallization shapes. Calcifications appear as lamellar crystals covering the pocket walls. (b) Semispherical deposits containing Ca and P (see EDS spectrum in Figure 6(b)) localized on the walls of the micro-cavity (niches) observed within the organic matrix where Ca and P are below detection limit. Images at higher magnification showed that spherical and semispherical deposits together with lamellar crystals were in turn formed by submicrometer globular structures. (c) Local pocket filled by spherical particles variable in size. Therefore, different crystal shapes observed within the niches appear to be due to different spatial arrangement of submicrometer particles. Scale bars are placed in different ways in the pictures because images were obtained by two different scanning electron microscopes: Figures (a) and (b) are from Hitachi S4000 and (c) is from Zeiss DSM 940.

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