[Maturation of mammalian bone minerals. A new method for determining bone metabolism]

The present report begins by comparing data on bone mineralization communicated in the literature to date with the authors' own previously published concept of the "three-phase model". The age-dependent accumulation of minerals in the femurs of Wistar rats was also chemically-analytically investigated. The results suggest that the mineral first formed is octacalcium phosphate. It is followed by sodium- and magnesium-containing phases. Maturation of octacalcium phosphate only occurs after this; it is converted into a highly carbon-deficient hydroxyapatite. During this conversion the molar Ca/P ratio rises from 1.33 to 2. However, the final value of 2 is not fully attained: this is attributable to the "turnover" activity of bone-metabolic processes. The paper concludes with a discussion of how the newly developed chemical method of determining bone turnover can be used to determine its vitality.