In investigating pathological changes that occur during development of fibrosis in lungs exposed to silica, we found a significant increase in apoptotic cells in rats exposed to silica by inhalation for 80 days. Since silica is not definitively detected at the light level, we sought to use SEM backscatter imaging to correlate the presence of silica with apoptosis identified by fluorescent assays. To accomplish this, paraffin sections of lungs from rats that had been exposed to silica were placed on carbon planchets. Serial sections were placed on glass slides, immediately before and after the section on the planchet. Using a fluorescein apoptosis detection system (Promega G3250), a TdT-mediated dUTP nick-end labeling (TUNEL) assay was performed on both planchets and slides. The planchets and slides were cover slipped with gel/mount (Biomedia) and viewed in an Olympus AZ70 fluorescent photomicroscope with a wide band blue filter cube. Apoptotic nuclei could be seen in similar regions in both the slide and the planchet preparations.