[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.