MINERALIZATION OF COLLAGEN MAY OCCUR ON FIBRIL SURFACES - EVIDENCE FROM CONVENTIONAL AND HIGH-VOLTAGE ELECTRON-MICROSCOPY AND 3-DIMENSIONALIMAGING

The interaction between collagen and mineral crystals in the normally calcifying leg tendons from the domestic turkey, Meleagris gallopavo h as been investigated at an ultrastructural level with conventional and high-voltage electron microscopy, computed tomography, and three-dime nsional image reconstruction methods. Specimens treated by either aque ous or anhydrous techniques and resin-embedded were appropriately sect ioned and regions of early tendon mineralization were photographed. On the basis of individual photomicrographs, stereoscopic pairs of image s, and tomographic three-dimensional image reconstructions, platelet-s haped crystals may be demonstrated for the first time in association w ith the surface of collagen fibrils. Mineral is also observed in close ly parallel arrays within collagen hole and overlap zones. The mineral deposition at these spatially distinct locations in the tendon provid es insight into possible means by which calcification is mediated by c ollagen as a fundamental event in skeletal and dental formation among vertebrates. (C) 1996 Academic Press, Inc.