Guiding principles of specimen preservation for confocal fluorescence microscopy

Traditionally, biologists have been confined to transmission electron microscopy (TEM) and light microscopy (LM) in order to correlate biochemical and molecular data with morphology. Electron microscopy (EM) provides fine ultrastructural detail but is limited to the study of cellular structures that react with electron dense stains deposited in fixed specimens. Immunogold labeling permits the study of non-electron-dense material, but EM sections must still be very thin to avoid problems with the penetration of the labeled antibodies and to reduce scattering of the electron beam.