ULTRASTRUCTURE AND X-RAY MICROANALYTICAL STUDY OF HUMAN PINEAL CONCRETIONS

We examined human pineal concretions and found them to exhibit a multi -layered concentric structure consisting of irregularly spaced dense a nd sparse zones containing fine crystals. The hydroxyapatite crystalli tes were shown to be irregularly outlined plate forms (measuring 11 si milar to 70 nm in their longest dimension and 2 similar to 10 nm in th ickness). At the center of each crystallite a central dark line was ob served by means of high resolution electron microscopy. The structure and size of the crystals were similar to those of dentin and bone. The ground surface of the concretions was observed metallurgically by mea ns of an electron probe microanalyzer (EPMA). The surface zones of the concretions contained a higher concentration of zinc, which seems to play an important role during the mineralization process, whereas calc ium and phosphorus exhibited higher concentrations at the center.