Zinc mapping in bone tissues by histochemistry and synchrotron radiation-induced X-ray emission: Correlation with the distribution of alkaline phosphatase

Zinc distribution in osteons was mapped by synchrotron radiation-induced X- ray emission analysis in both human and porcine adult bone, as well as in p orcine bone by histochemistry using Timm's method, Both procedures showed t hat zinc is not uniformly distributed, being in its highest concentration o n haversian bone surfaces. When Timm's method was applied in conjunction wi th a procedure leading to partial zinc extraction, three zinc pools were sp ecifically detected: a loose one, found in the mineralizable osteoid; a min eral one, bound to the bone mineral; and a tenacious one, firmly bound to a n organic component located in the osteoid and mineralizing organic matrix. The alkaline phosphatase distribution was also mapped in porcine adult bon e by histochemistry and immunohistochemistry and it was found codistributed with tenacious zinc mainly at the calcification front, The data suggest th at alkaline phosphatase is buried as a bone matrix protein during initial m ineralization, (C) 1999 by Elsevier Science Inc. All rights reserved.