Silver methenamine staining for scanning electron microscopy of bone sections containing biomaterials

Sections of tissue containing orthopedic materials are currently used to st udy the compatibility of those materials and to perform electron probe micr oanalysis at the material-tissue interface. Identification of the cells in contact with the material by Scanning electron microscopy (SEM) is of inter est. We have developed a method for staining cells and tissue structures em bedded in polymethyl methacrylate with silver methenamine once the sections have been obtained. Sections were prepared by grinding, and the silver met henamine was applied after oxidation with periodic acid. The procedure was carried out in a microwave oven. Backscatter SEM showed staining of the cel l nucleus membrane, chromatin, the nuclear organizers, and the chromosomes of dividing cells, The cytoplasm and the cytoplasmic membrane were also sta ined. Collagen fibers of the extracellular matrix and the mineralized matri x of bone were labeled. Material particles in the macrophages were easily r ecognizable and Energy-Dispersive Spectrometer were not impaired by the pre sence of silver in the preparation.