SPHERULITIC BRUSHITE STONES IN THE DENTAL-PULP OF A COW

Pulp stones of human teeth usually contain biological apatite. In the dental pulp of a cow, aged 12 years, we observed spherulitic pulp ston es, up to similar to 200 mu m in diameter, consisting of radially arra nged crystals with several kinds of light microscopy and scanning elec tron microscopy including the secondary electron and the backscattered electron signals. The crystals extending fan-like towards the periphe ry showed a rectangular shape, and they had subunits of elongated crys tallites and fine slits of NaOCl-dissolved substances, probably includ ing organic matter and amorphous mineral. By using energy-dispersive X -ray microanalysis, large amounts of Ca and P, and trace elements of N a, Mg, Cl, and Fe were detected from the stones. The calcium phosphate crystals were identified as biolgical brushite by shape, Ca/P molar r atio, and electron diffraction pattern. Core regions of the stones con taining granular structures, probably erythrocytes, were always presen t in blood vessels, and rectangular crystals frequently penetrated the vessel walls. Under the decalcified sections, the nidi were completel y or incompletely dissolved, but the peripheries showed a radial arran gement of erythrocytes. Thus, the nidi may be thrombus or necrotic blo od cells including erythrocytes. Such calcospherulites in the dental p ulp of a cow were similar to the spherulitic pulp stones in human deci duous teeth reported previously, however, their nidi were present in d ifferent regions.