Effect of crystal growth on the comparative fixation of Sr89 and Ca45 by calcified tissues.

In a previous paper (1) it was shown that discrimination against strontium as compared to calcium, in the formation of synthetic hydroxyapatite, Calo(POJ)6(OH)2, was greater in large, more slowly grown crystals than in small, more rapidly precipitated crystals. The exclusion of strontium as compared to calcium in the hydroxyapatite crystals increases as the preparation conditions approach equilibrium. Since the mineral portions of some calcified tissues differ in crystal size (2, 3), an experiment was designed to test whether crystal size and strain as relatrd to rate of crystal growth affects the relative incorporation of Wg and Ca45 in vivo.