Fractographic Studies of Plastic-embedded Cells by Scanning Electron Microscopy

Three-dimensional views of cell structures at high magnifications made possible by the scanning electron microscope (SEM) are becoming increasingly useful to biologists. Methods that have proved useful for stabilizing biological soft tissue for observation in the SEM include the critical point method (1, 2), freeze drying, freeze fracturing followed by freeze drying (4, 9, 10), observation of specimens frozen and fractured in the SEM specimen stage (7), and applied glycerol substitutions (8). Viewing animal cells embedded and fractured in plastic is a convenient alternative for studying both extracellular and intracellular structures. The method permits a direct comparison of structures seen by the SEM with structures viewed by transmission electron microscopy in ultrathin sections cut from the same embedment in the same block.