Immunofluorescence with mouse anti-alpha-tubulin was employed to visualize details of the microtubule network in the log phase monolayer culture of gerbil lung cells presented above. The secondary antibody (goat anti-mouse IgG) was conjugated to Alexa Fluor 555 (pseudocolored green). Nuclei were counterstained with TO-PRO-3, a carbocyanine monomer with long-wavelength red fluorescence. Images were recorded with a 60x oil immersion objective using a zoom factor of 3.0 and sequential scanning with 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.