Cell Labeling and FIB–SEM Imaging

Volume electron microscopy is a powerful method for the study of brain connectivity at the ultrastructural level. Synapses and their parent axons and dendrites can be traced within the three-dimensional tissue sample, so their numbers and distribution can be quantified in different brain regions and in different conditions of health or disease. Cell labeling methods allow us to identify the nature and origin of nerve fibers. Here we briefly review several labeling methods that have been combined with Focused Ion Beam–Scanning Electron Microscopy (FIB–SEM). We describe the different methods used and the technical difficulties that they pose.