A coronal section of rat brain cerebral cortex (shown above) was immunofluorescently labeled for heavy chain neurofilament subunits with chicken anti-NF-H antibodies followed by goat anti-chicken secondary antibodies conjugated to Alexa Fluor 568 (red fluorescence). Neurofilaments, which are found primarily in the axons of neurons, are composed of light (NF-L) and medium (NF-M) chain subunits in addition to NF-H. Glial fibrillary acidic protein was also targeted in the tissue section by treating the specimen with rabbit anti-GFAP antibodies visualized with goat anti-rabbit secondary antibodies conjugated to Alexa Fluor 488 (green fluorescence). Nuclear DNA was counterstained with DRAQ5 (pseudocolored cyan). Images were recorded with a 20x objective using a zoom factor of 1.5 and sequential scanning with the 488-nanometer spectral line of an argon-ion laser, the 543-nanometer line from a green helium-neon laser, and the 633-nanometer line of a red helium-neon laser. During the processing stage, individual image channels were pseudocolored with RGB values corresponding to each of the fluorophore emission spectral profiles unless otherwise noted above.