When turtle retinae were incubated with the fluorescent dye, lucifer yellow, in the absence of Ca2+, the dye was selectively accumulated by cell bodies located in the inner nuclear layer (INL). The morphological features of the labeled cells suggested that they were bipolar cells. Other fluorescent dyes, Procion yellow and Primulin, were also taken up by somata in the INL, in the absence of external Ca2+, although the identity of the labeled cells was uncertain. As with turtle retina, lucifer yellow was accumulated predominantly by cell bodies in the INL of goldfish, frog, and rat retinae. Lucifer yellow uptake appeared to be independent of synaptic activity since dark‐adaptation or aspartate treatment of retinae did not alter the dye uptake. Further, retinae from dystrophic (RCS) rats showed uptake similar to that seen in normal rat retinae. After uptake, most of the dye was found intracellularly as patches or vacuoles in the somata of the labeled cells. Dye uptake was not inhibited by removal of Na+ from the incubation medium. Further, prior treatment with metabolic inhibitors, cyanide and iodoacetate, or cytochalasin B, did not block the dye uptake.
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