Microradiographs were prepared of carefully washed 200 μm ground sections of human mandibular cortical bone: these sections were then extracted with hot 1,2 ethane diamine in a soxhlet apparatus, washed with alcohol, dried, given a conducting coating of carbon and gold and photographed in a Cambridge Scientific Instruments Stereoscan MKI scanning electron microscope operated at 10 kV. A good correlation was found between the interpretation of the microradiographic image given by Jowseyet al. (1965), and our previous interpretation of the scanning electron microscopic image of bone surfaces (Boyde and Hobdell, 1969). A new type of forming surface has been encountered in scanning electron micrographs of the depths of previous resorption lacunae in which new bone formation has just commenced. The mineral presents as microcalcospheritic nodules - the collagen fibre bundles cannot be recognised. Poorly mineralized osteones appear brighter in the scanning electron microscope image of the surface of 1,2 ethane-diamine extracted sections: the same regions also show a pattern of broad, low, flat ridges, corresponding to the dimensions of the lamellae proper, and narrow grooves which would be attributed to the interlamellar planes. It is probable that these two effects are interrelated and that interruption in the continuity of the conducting coating at cracks located at the interlamellar planes causes the isolation and insulation of islands" which charge up under the electron beam. © 1969 Springer-Verlag."
