Fig. 3

 GFP expression in the CNS of Tg(gfap:GFP) embryos with comparisons to glial and neuronal markers in cryosections. (A) In the retina at 96 hpf, GFP expression (green) is exclusively in Müller glia. Their cell bodies are located in the inner nuclear layer (inl) and radial processes extend from the inner limiting membrane, the boundary of the ganglion cell layer (gcl), to the outer limiting membrane, the boundary of the outer nuclear layer (arrowhead). Fine lateral processes of the Müller cells fill the inner plexiform layer (ipl). (A′) Anti-GFAP (magenta) labels intermediate filaments that are predominately located in the inner radial processes and endfeet of the Müller glia at the inner limiting membrane. (A″) All Müller processes labeled with anti-GFAP also show GFP expression. (B) In a transverse section through the hindbrain of a 96 hpf embryo. GFP-positive radial glia cell bodies (arrow) are near the ventricular surface and radial processes extend outwards to the pial surface (arrowheads). (B′, B″) The GFP-positive glial processes are also labeled by anti-GFAP. (C) A transverse section through the spinal cord of a 72 hpf zebrafish. GFP-positive cells surround the central canal and some have processes extending to the pial surface. (C′) Anti-calretinin (magenta) labels spinal neurons lateral to the central canal, but does not label any GFP-positive cells (C″). (D) Transverse section through the midbrain of a 72 hpf zebrafish reveals GFP-positive cell bodies adjacent to the ventricle (arrow) and less intensely labeled cells further from the ventricle (arrowheads). (D′) Overlay of HuC/D (magenta) and DAPI (blue) images reveals that the majority of cells are HuC/D-positive with the exception of cells adjacent to the ventricle (arrow). (D″) Overlay of the GFP and HuC/D images shows many of the HuC/D positive cells near the ventricle are also GFP-positive. (E) Transverse section through the midbrain of a 1-month-old zebrafish. GFP-positive cells are located along the ventricle (arrow) and extend processes toward the pial surface. (E′) Overlay of HuC/D and DAPI images. (E″). HuC/D-positive neurons are no longer GFP-positive, except for an occasional cell close to the ventricle (arrowhead). Scale bar: 40 μm (A, D, and E); 30 μm (B); or 15 μm (C).