Positive controls showing expression in known antigen-positive cells in the nervous system of zebrafish (A,B). (A) In a transverse section through the spinal cord, GFAP-positive radial glia processes (arrowheads) extend from the periependymal zone to the meningeal surface. They are thicker in the dorsal and ventral horns. (B) Transverse sectioned spinal cord showing vimentin immunopositive radial glia processes (arrowheads). Immunopositivity is also found in the projecting roots of a spinal nerve. Curved arrows point out chromatophores in the dorso-lateral meningeal layer. D, dorsal horn; DR, dorsal root; M, meningeal surface; P, periependymal zone; V, ventral horn; VR, ventral root. Scale bars: 100 μm.