Crystallinity of human pineal calcospherulites

Crystallinity of mineral in human pineal calcospherulites was determined by electron spin resonance spectrometry after irradiation of the samples with gamma rays in a 60Co-source. The radiation-induced stable paramagnetic centers in the crystalline lattice of hydroxyapatite crystals were used as a marker of the crystalline fraction and related to the total mineral content. The crystallinity of pineal sand is higher than that of compact bone. The numerical value of the crystallinity coefficient depends on both the average crystal size of hydroxyapatite and the percentage of the crystalline fraction in the total amount of mineral. Literature data show that the average size of hydroxyapatite crystals in pineal sand are smaller than in bone tissue. It is, therefore, concluded that the higher crystallinity of pineal acervuli is due to the lower percentage of the submicrocrystalline fraction in their mineral.