Scanning-electron microscopy studies of 'ground substance' in the cement lines, resting lines, hypercalcified rings and reversal lines of human cortical bone.

Adult human cortical bone was decalcified and stained with Harris's hematoxylin, which has a strong affinity for cement lines, resting lines, hypercalcified rings and reversal lines. Small pieces of bone tissue containing these morphological entities were then dissected and manipulated mechanically so as to disrupt them partially. Scanning electron microscopy of these regions of interest revealed the presence of relatively large concentrations of amorphous 'ground substance' which was morphologically distinguishable from the fibrous collagen fiber bundles located in the adjoining collagen-rich lamellae. The methodology used in this study confirms the existence of the above-mentioned regions as true morphological entities and also makes possible enzymatic studies designed to identify the major biochemical components constituting the observed 'ground substance'.