Previous Nature 195, 911THE mechanism of calcification has been considerably clarified recently1. Collagen fibrils were shown to possess in vitro the property of nucleating hydroxyapatite precipitation and of triggering mineralization1 But why does only part of the collagen present in the organism calcify ? Recently love bracelet replica, we suggested that the activating sites of collagen and crystal growth could be blocked in the organism by a plasma inhibitor4. Indeed we showed plasma to contain one or several substances highly inhibitory to apatite precipitation pink gold cartier love bracelet. The technique used was to determine in vitro cartier love bracelet 17, at physiological conditions, the minimum ion product (Ca) (P) necessary for hydroxyapatite precipitation. After addition of plasma, the rise of this minimum product revealed the presence of inhibitors. As the inhibitor was shown to be destroyed by alkaline phosphatase, and the polyphosphates to have a strong inhibitory activity at concentrations as low as 10 M, we suggested this inhibitor to be a polyphosphate. However, to our knowledge, no such compound has so far been demonstrated in plasma or in urine.