Chemical and physicochemical studies on the mineral deposits of the human atherosclerotic aorta.

The mineral deposits of the human atherosclerotic aorta were prepared by a new method characterized by the use of mild conditions. Both large and small mineral deposits were isolated from the atherosclerotic plaque and were shown to possess essentially the same chemical composition. The deposits consisted mainly of calcium apatite (71%), carbonate (9%) and contained a relatively high percentage of protein (15%). X-ray diffraction pattern analysis revealed the presence of microcrystals with an average size of approximately 0.1 micron. Electron probe analysis showed that the surface and interior of the mineral deposit had the same chemical composition. However, scanning electron microscopy revealed that the deposits were heterogeneous and consisted of five different structures: (1) individual and conglomerates of smooth-surfaced apheres consisting of spherical layers; (2) spheres consisting of spindle-like, radially arranged particles; (3) fibres forming networks and bundles which sometimes included spherical particles; (4) irregularly shaped particles with fuzzy surfaces and (5) flat plates with smooth surfaces.