A Wet Chemical Method for Rendering Scanning Electron Microscopy Samples Conductive and Observations on the Surface Morphology of Human Erythrocytes and Ehrlich Ascites Cells

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Abstract
An alternate method to the common technique of evaporating a metallic coating on cells to render them conductive for scanning electron microscopy is described. This wet chemical technique is less expensive and easier to use, but is not as widely applicable as the evaporative technique. It should prove invaluable in the identification of artifacts by comparison of micrographs of material prepared in both manners. The first step in our application of this wet chemical method is to use the Centrifugal Cytology bucket to deposit the cells onto conductive polyethylene. After centrifugation and fixation with 4% glutaraldehyde, the sample is placed in a 50% glutaraldehyde solution. After a rinse in distilled water it is treated with ammoniacal silver nitrate. The reduced silver renders the sample conductive and, thus, for erythrocytes, eliminates artifacts due to charging and reduces these artifacts to virtually acceptable levels for larger cells. The surfaces of erythrocytes appear smooth with this technique while those coated by conventional vapor deposition of Au-Pd alloys often appear slightly wrinkled. Ehrlich ascites cells apparently can be divided into two classes by surface morphology. The surface structure of Ehrlich ascites cells rendered conductive by the wet method appears to be finer than conventionally prepared ones.