ABSTRACT
Classical histology of the nervous system has used either cationic dyes or silver stains. Cationic dyes such as cresyl violet or toluidine blue bind to the negatively charged phosphate groups of nucleic acids in nucleus, nucleolus and Nissl bodies and so show cell bodies. The dye diffuses through much of the neurites so the morphology of the cell can subsequently be revealed by fluorescence microscopy of brain slices. The fluorescence dyes can be visualized directly by fluorescence microscopy, and radiolabeled compounds revealed by autoradiography. Retrograde horseradish peroxidase (HRP) is used to identify the location of cell bodies associated with identified terminals, but HRP only reveals the morphology of a neuron fully when used in the anterograde direction. The location of particular proteins such as enzymes or receptors can be determined using either polyclonal or monoclonal IgG antibodies. Antibodies can also be produced against small molecules, such as neurotransmitters, by first conjugating them to a protein.
