Visualization of desmosomes in the electron microscope.

Desmosomes are intercellular junctions found in epithelia and some other tissues. Their primary function is strong cell-cell adhesion. They also link the intermediate filament (IF) cytoskeletons between cells and have roles in cell signaling, tissue morphogenesis, and wound repair. Because of their size (0.2-0.5 microm), details of their ultrastructure can only be resolved at the electron microscope (EM) level. Desmosomes have been visualized using a variety of ultrastructural techniques including lanthanum infiltration, freeze-fracture, electron tomography, cryo-electron microscopy and immunogold labeling. This chapter describes protocols for conventional transmission electron microscopy and for immunogold labeling of ultrathin cryosections. We also discuss the statistical analysis of immunogold particle distribution for low resolution molecular mapping.