Simultaneous Study of Both the Surface and Interior Structure of Biological Specimens in a Scanning Electron Microscope
In contrast to optical and transmission electron microscopes, which probe the interior, the scanning electron microscope usually only reveals the exterior structure of the specimen to the biologist. This is due both to the collection of secondary electrons as signal and to the practice of coating the specimen with various heavy, noble metals.Taking advantage of their penetrating power, one can use backscattered electrons to study the interior structure of the biological specimen in a scanning electron microscope. Here a block of specimen is first stained by means similar to those practiced in transmission electron microscopy. Then a coating of carbon is applied to supress the undesirable specimen charge-up. Although the resolution in this mode will be degraded by electron-atom scattering events, this approach promises to yield more histochemical information than studying merely the topography of the specimen.