LOCALIZATION OF NITRIC-OXIDE SYNTHASE IN THE GOLDFISH RETINA

The localization of nitric oxide synthase and NADPH-diaphorase was stu died in the goldfish retina by means of immunohistochemistry or tetraz olium salt technique. Nitric oxide synthase was found in some small ne urons of the inner nuclear layer and in large neurons of the ganglion cell layer. The reaction product was localized in the outer plexiform layer and a diffuse labeling was also observed in the inner plexiform layer. In addition to the outer segments of photoreceptors, NADPH-diap horase labeled several neurons of the inner nuclear layer and some neu rons scattered in the ganglion cell layer. Both outer and inner plexif orm layers were labeled. Ultrastructural observations showed that the reaction product was found to be bound to the endoplasmic membranes of positive neurons. In the outer plexiform layer the formazan precipita te labeled prevailingly the presynaptic terminals of rods and cones, i n the inner plexiform layer both pre- and postsynaptic profiles showed the reaction product.