ABSTRACT
Collagen is the major constituent of the organic matrix of bone and is present in other calcifying tissues. Consequently, although calcification can occur in noncollagenous matrices, as for instance enamel matrix, the role of collagen fibrils in inducing and regulating the calcification process is considered of primary importance. The intimate relationship which links collagen fibrils and inorganic crystallites in bone was shown by the early electron microscope investigation of Robinson and Watson, who, developing previous studies, described crystallites aligned along the collagen fibrils and often in line with their periodic banding. Knowledge of structure, composition, and molecular arrangement of collagen fibrils is essential to understand their role in calcification. However, complete study of the molecular array in collagen fibrils of bone and other calcified tissues is to some extent prevented by the necessity that bone matrix is decalcified to unmask the collagen fibrils.
