[Light and electron microscopic observation of zinc distribution in the carp retina]

Localization of zinc in the carp retina in both light and dark adaptation was investigated using neo-Timm sulfate silver method. The results showed that in light adaptation, zinc was preponderantly present in the outer plexiform layer (OPL). Both terminals of zinc containing photoreceptors and dendrites of bipolar cells usually extend into zinc staining areas in OPL. In dark adaptation, zinc staining in retina is blanched or only appeared in cytoplasmic bodies of few cones. There is no significant difference between dark and light adaptation in the zinc distribution in bipolar, amacrine and ganglion cells. The fact that zinc is perched in the carp retina between photoreceptors and second-order neurons of the visual pathways in OPL in light adaptation and significantly released in dark adaptation suggests that zinc might play some modulatory roles in the visual signal transduction.