Classification of nAChRβ2-immunoreactive retinal ganglion cells and their tectal projections in chicks

The relationship between the type of retinal ganglion cell (RGC) and the retinoreceptive layer of the tectum is investigated by the immunostaining of RGCs with nicotinic acetylcholine receptorβ2 (nAChRβ2) antibody and intracellular staining by DiI and also by anterograde degeneration and biotinylated dextran amine labeling of retinotectal fibers in chicks. The results strongly suggest that many of the RGCs that express immunoreactivity to nAChRβ2 send axons to tectal layer 7 and are mainly classified into the simple-type of Groups II and III, which contain the cells providing middle-sized to large dendritic fields with simple dendritic arborization. These nAChRβ2-immunoreactive RGCs receive visual information via the multiple sublayers of the inner plexiform layer.