One to one correlation of histological and histochemical light microscopy with scanning electron microscopy

Several histological stains were applied to specimens after scanning electron microscopic (SEM) processing. Histochemical stains were applied before SEM fixation. After staining, the specimens were processed and dried by SEM techniques. The specimens were taped to a microslide, specimen side up, scribed and covered with immersion oil. After light micrography (LM), the oil was removed and the specimens mounted and gold coated. The same cells were then relocated and photographed by SEM. Periodic acid Schiff was not usable as a specific tissue aldehyde stain, but did prove to be a useful counterstain for dehydrogenase stained specimens. Colloidal iron, as seen by SEM, resulted in a non-specific granular deposit over the specimen and the substrate. All the other histological stains examined--alcian blue, Grams, Feulgen and toluidine blue--were specific and did not change the specimen ultrastructure. The histochemical stains--acid and alkaline phosphatase and three dehydrogenases--were also specific. There were some minor ultrastructural changes with the AcPase and AlPase stains. However, the tissue surface was not significantly distorted. These and other techniques should prove to be a useful adjunct to SEM studies.