Figure 4.
GFP+ progenitors express neuronal and photoreceptor markers. a–e, Retinal cryosections from juvenile Tg(gfap:GFP)mi2001 zebrafish labeled with 7 d continuous exposure to BrdU (red). Counterstained for nuclei with DAPI (blue) and Pax6, Crx, or Rho4D2 (magenta). a, b, BrdU+, Pax6+ neural progenitors in the inner nuclear layer (inl; arrowheads) are weakly labeled with GFP (green). b, Nonproliferating (BrdU−) Müller glia are strongly labeled with GFP and weakly immunoreactive for Pax6 (arrow). c, A GFP+, BrdU+ neural progenitor in the outer nuclear layer (onl) is immunoreactive for Crx (arrowhead). d, A pair of BrdU+ nuclei (arrowhead) in which the upper cell is Crx+ and weakly GFP+, and the lower cell is Crx−, strongly GFP+, and has a polygonal-shaped nucleus characteristic of Müller glia. e, A GFP+, BrdU+ cell in the ONL is immunoreactive for rod opsin (Rho4D2; arrowhead). Scale bar: (in a) a, c, 15 μm; b, e, 10 μm; d, 12 μm.