Images of retina from ZDR (A) and Tg( gfap :GFP) (B, C, D) zebrafish showing localization of anti-GFAP, anti-cytokeratin, and GFP. (A, B, C, 20× water immersion, NA 0.95; D 60× oil immersion, NA 1.4). 2A. An image of retina from a ZDR fish immunostained with anti-GFAP (red) and DAPI (blue). Strong labeling in the foot processes (fp) of Müller glia extending between the RGC nuclei (rgcn) into the inner plexiform layer is apparent. In addition, the Müller glial elements of the outer plexiform layer (opl) are brightly decorated, with fainter labeling extending to the outer limiting membrane. The scale bar represents 55 μm. 2B. Bright GFP fluorescence can be observed in Müller glia extending from the foot processes (fp) at the inner limiting membrane, through the outer plexiform layer (opl), to the outer limiting membrane (olm). The Müller soma (mgs) are visible among the nuclei of the amacrine cells. Note the distribution of GFAP as indicated by anti-GFAP (Figure 2A) is limited to certain regions of the Müller cells and differs from distribution of GFP expressed under a transgene promoter; GFP appears to illuminate all parts of the cell. The scale bar represents 85 μm. 2C. An image of retina from Tg(gfap:GFP) fish has been immunostained for anti-cytokeratin (magenta). As in Figure 2B, GFP fluorescence delineates Müller glia cells from the outer limiting membrane (olm) to the inner limiting membrane (ilm). Bright anti-cytokeratin labeling can be seen on the inner limiting membrane and in the cytoplasm of cells among the bundled fiber layer (bfl). Less intense cytokeratin labeling is apparent in the inner plexiform layer (ipl). The scale bar represents 70 μm. 2D. Similar to Figure 2C, at higher magnification showing details of the inner segments of the Müller glial cells and anti-cytokeratin labeling of the inner limiting membrane (ilm). Oblong nuclei characteristic of oligodendrocytes can be seen in the nerve fiber layer. The arrow at lower right indicates a blood vessel. The scale bar represents 50 μm.