Tissue calcification of the cardiovascular system

The cardinal problem of biomineralogy, and namely of medical mineralogy, is the detection of processes and regularities of mineralization in the human organism. Calcium phosphate is the principal inorganic phase in the pathogenic calcification of the collagenic and muscular tissues of the cardiovascular system (CVS), as well as of the physiogenic bone and dental tissues. Calcium phosphate is assigned to carboniferous hydroxylapatite with a certain degree of approximation and idealization. The biogenic apatite is closely connected genetically and spatially with the body tissues. In the course of research, it is very important to retain the tissue-mineral contact zone at the most. So, ignition of calcine tissues and mechanical separation of biominerals from the organic matrix applied by numerous investigators interferes with studying the minerogenesis in the organism. Highly efficient, precise physical-chemical techniques are regularly applied to studying the human biominerals, but such mineralogical methods as mineragraphy and immersion have never been used. The light polarization microscopy, roentgenostructural and microprobe analyses have been applied to study over 500 samples of the calcined cardiovascular tissue (CVT). The sequence of the pathogenic bioapatite crystallization has originally been established in the CVS. The CVT ectopic mineralization is initiated by matrix vesicles (MV), that is, membrane-enclosed vesicle-like particles. The crystallization process in MV includes three stages. At the first stage, the MV are isotropic in the crossed nicols because an incipient crystal is linearly too small for the light microscopy. The second stage is characterized by the flattening of the oval-elongated MV attaining the non-uniform double refraction within the vesicle exterior transparent part. The turbid substance therewith is formed and concentrated in the centre of MV. At the third stage, the growing apatite crystals penetrate the MV membranes, and the ellipsoidal vesicles combine into parallel lamellar layers. The turbid cores are transformed into the discontinuous linear inclusions within the ectopic apatite, which are absolutely opaque with well-defined boundaries. There are no similar inclusions within the physiogenic apatite. The results of the light polarization microscopy, roentgenostructural and microprobe analyses enable the conclusion to be made that ectopic bioapatite is characterized by regular changeability of its linear, crystallographic, optical, micro- and macrochemical properties. The research of the pathogenic bioapatite should be carried out with regard to its changeability at the micro- and nanolevels. The study of the pathogenic bioapatite and processes involved in its origination and interaction with adjacent tissues would be impossible without considering constant regular changes in its structure, composition, dimensions and crystallographic characteristics

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