Preparation of cells from suspensions for correlative scanning electron and interference microscopy

Neutrophils from bovine milk and blood platelets from dog plasma were washed in PBS, fixed in GA, dehydrated, suspended in a drop on a formvar-coated slide and immediately critical-point-dried in CO2. After coating with Pt-Pd the specimens were examined in an SEM. The same cells were then examined by interferometry (Int) in a light microscope, and the dry mass was determined. It is shown that this preparation method for both types of microscopes (SEM and Int) appears to give adequate results as far as fine surface structure (SEM-appearance) and dry mass determinations (Int) are concerned. The method has the advantage of a more precise characterization of individual particles, than would have been possible, if both methods of microscopy (SEM and Int) had been employed on the same sample, but on different specimens.