[Ultrastructural features of hydroxyapatite crystals of thoracic vertebrae in the middle-aged and aged persons].

Bone tissue samples of thoracic vertebrae taken from 32 cadavers of males and females who had suddenly died at ages were examined ranging from 20 to 45 and from 70 to 89 years. The samples were studied by means of quantitative phase X-ray analysis which showed the mineral component of the crystalline phase to be 55.8 +/- 2.1 and 56.6 +/- 2.2 per cent in the young men and women, and that of the older-age group to be 63.9 +/- 1.9 and 66.1 +/- 2.6 per cent, respectively. The hydroxyapatite crystals had the shape of a hexagonal prism with 23.8-27.3 nm allongated along the C axis. The crystal dimensions along the a axis in the young males were 7.0 +/- 0.15 nm, that of females were 6.8 +/- 0.2 nm; in the old-age group, the dimensions were 7.7 +/- 0.2 and 7.4 +/- 0.14 nm, respectively. The volume of the crystallized particles in the young was 1387 +/- 66 nm3 and increased with age to 1748 +/- 117 nm3. The findings on the ultrastructure of the mineral component and its age-related changes may be used to study the physicochemical properties of the bone and to reveal the essence of aging of the locomotor apparatus and of the organism as a whole.