SELECTIVE ACCUMULATION OF DIAMIDINO YELLOW AND CHROMOMYCIN-A3 BY RETINAL GLIAL-CELLS

We applied the fluorescent DNA stains diamidino yellow (DY) and chromo mycin A3 to rat and rabbit retinas in vivo and in vitro. They accumula ted in the nuclei of a subpopulation of cells of the inner nuclear lay er. The number and distribution of the fluorochrome-accumulating cells were similar to those of the Muller glia, and double-labeling experim ents showed that the cells accumulating DY or chromomycin A3 contained oriented filaments of vimentin. The fluorochromes also accumulated in the sparse astrocytes and oligodendrocytes located among the myelinat ed fibers of the rabbit central retina. Specific accumulation in retin al glia occurred only when the fluorochromes were applied to living re tinas. If the plasma membranes were disrupted by fixation or exposure to detergent, most retinal cells were stained. This indicates that the locus of specificity is the entry of the molecules into the cells. Wh en applied to living retinas, other DNA stains selectively accumulate in subclasses of retinal neurons. Why DNA-binding molecules should sel ectively cross the membranes of either retinal neurons or retinal glia remains an unsolved problem.