Preparation of experimental animal tissue for SEM

Methods for preparing experimental animal tissues for the scanning electron microscope (SEM) have evolved from so many sources, with such lack of standardization that interpretation of the results is difficult, and inter-investigation comparisons usually impossible. To distinguish the surface changes inherent in any protocol for the preparation of bulk tissue blocks from those produced by experimentation or disease, the preparative procedures must become standardized at least to the extent that preparation for light microscopy (LM) and transmission electron microscopy (TEM) is standardized. Rationales for the selection of a particular preparative procedure which will result in minimal alteration from the living tissue are discussed. The methods for handling the specimen, stabilization, dehydration and drying, rendering the surface conductive, and exposing the surface of interest are described for a wide variety of experimental animals. The use of SEM to yield maximum morphological information in the secondary electron mode is also described, as are the methods used for evaluating the results in terms of minimal distortion due to preparative procedures.