ABSTRACT
In the conducting airways, the use of electron microscopy has clarified the interrelationships of secretory epithelial cells and remains the only technique that can be used to identify brush cells, for which investigators know of no unique secretory product or immunological marker. Two types of electron microscope are widely available: transmission electron microscopes (TEMs) and scanning electron microscopes (SEMs). The basic procedures for TEM include fixation, dehydration, embedding, sectioning, and staining. Dehydration is an obligatory step before infiltration with any of the commonly used embedding materials. The first application of SEM to lung was to study particle deposition. SEM has proven to be a sensitive way to detect focal abnormalities, selective for one part of the acinus. Three steps are involved in preparing tissue for SEM: fixation, dehydration, and coating. Fixation must be done by a method that expands the lung to open the airspaces and expose the surfaces.
