Antibodies against filamentous components in discrete cell types of the mouse retina

Three monoclonal antibodies have been raised against the ganglion cell layer of the adult mouse retina. The first antibody, R3, labeled optic axons in the inner retina, and with colchicine pretreatment somata and dendrites of large ganglion cells could be seen. A small number of other processes, including fibers projecting to the retina from elsewhere (efferent fibers), were also labeled in the inner retina. In the outer plexiform layer R3 stained the axonless class of horizontal cells. R3 recognized a 185,000- to 200,000-dalton polypeptide which is most probably the heaviest of the neurofilament subunits. Antibodies R4 and R5 labeled filamentous components mainly in glia and cells of mesenchymal origin. The antigens appeared in most but not quite all locations morphologically closely related to the intermediate filament protein vimentin. In the retina both antibodies labeled strongly the regularly spaced Müller glia. The astroglia of the optic fiber layer was stained with R5 but not R4. Although the two antigens were in general not expressed in neurons, they were both present in axonless horizontal cells in the outer plexiform layer, coexisting with neurofilaments in this neuron.