AN IMMUNOCYTOCHEMICAL MARKER FOR HAMSTER RETINAL GANGLION-CELLS

We examined the specificity and developmental time course of the label ling of retinal ganglion cells in Syrian hamsters by a monoclonal anti body AB5. In adult hamsters, AB5 selectively labelled somata in the ga nglion cell layer, dendrites in the inner plexiform layer and axons in the nerve fibre layer. When retinal ganglion cells were retrogradely labelled with DiI prior to AB5 immunocytochemistry, all of the retrogr adely labelled retinal ganglion cells in the ganglion cell layer were AB5 immunoreactive, indicating that AB5 labels all classes of ganglion cell in that layer. In retinae depleted of retinal ganglion cells by neonatal optic nerve transections, AB5 did not label any somata or pro cesses, indicating that AB5 specifically labels retinal ganglion cells . During development, AB5 labelling first appeared as a weak staining of cell bodies in the ganglion cell layer on postnatal day 12 (P12; PO = first 24 h following birth) and acquired the staining pattern seen in the adult by postnatal day 14. From the onset of AB5 immunoreactivi ty, ABS-labelled somata of varying sizes were present across the entir e retinal surface. Although AB5 labelled retinal ganglion cell axons i n the nerve fibre layer of the retina it did not label the optic nerve or retinal ganglion cell axons in the brain at any age examined. AB5 labelling was also found to be compatible with bromodeoxyuridine immun ocytochemistry and, therefore, useful for determining the time of gene ration of hamster retinal ganglion cells.