13] Electron microscopical methods in adhesion

Abstract

Publisher Summary This chapter focuses on electron microscopical methods used in adhesion. Electron microscopy, mainly of negatively stained preparations, have been used to identify and characterize the proteinaceous flamentous bacterial surface structures, termed as “fimbriae’ or “pili,” which functions as adhesins. Electron microscopical studies of bacteria-cell interactions have mainly employ scanning electron microscopy (SEM) and transmission electron microscopy (TEM) of thin sections, together with associated immunological applications of other methods. An objective of all microscopy is to attain good contrast and resolution of a specimen. In negative staining, this is achieved by surrounding/embedding the specimen in a thin film of heavy metal stain such that unstained structures show up against the heavy metal stain in negative contrast. Immunocytochemical techniques are powerful tools for the localization of specific antigens. The development of colloidal gold probes revolutionized the electron microscopical application of such techniques. Bacterial adhesion is a cell surface interaction that makes it ideal for examination by SEM. SEM is mainly used to examine mucosal surfaces from both natural and experimental infections of animals and humans and to examine tissue and tissue culture cells experimentally infected in vitro .