Molecular characterization of postembryonic neurogenesis in the CMZ of the zebrafish retina. A) and B) Larval zebrafish (4 dpf). A) Mitotic retinal progenitor cells in the CMZ (arrow) immunoreactive for PCNA (green). B) rx1 (magenta) in the CMZ (arrow) and in differentiated cones in the outer nuclear layer (ONL). L, lens; GCL, ganglion cell layer, INL, inner nuclear layer. Scale bar = 50 μm. C) – J) Two-month-old juvenile zebrafish retinas. C) Cells in peripheral CMZ are double-labeled (white arrow) with rx1 (magenta) and PCNA (green). D) Cells in peripheral CMZ are double-labeled (white arrow) with vsx2 (magenta) and PCNA (green). E) Amacrine cells in the INL and ganglion cells in the GCL express pax6a, and many PCNA+ cells in the CMZ are double-labeled with pax6a (white arrow). F) Cells in the peripheral CMZ co-express rx1 (magenta) and pax6a (green). Scale bar = 50 μm. G) Cells in the CMZ (arrow) express notch1a (magenta). H) PCNA+ cells (green) in the CMZ, nonpigmented cells in the adjacent ciliary margin and Müller glia (arrows) in the differentiated retina adjacent to the CMZ are BLBP+. BLBP-immunoreactivity gradually disappears from Müller glia more centrally. I) Immunoreactivity for SSEA-1/LeX (green) around the circumferential blood vessel (BV) and in a narrow band of the inner plexiform layer, IPL. J) Immunoreactivity for N-cadherin protein (Cdh, magenta) completely surrounds the cell bodies of PNCA+ (green) mitotic cells in the CMZ and cells in the adjacent non-pigmented ciliary epithelium. In the laminated retina, N-cadherin is localized to the zonula adherens junctions of the outer limiting membrane (arrowhead) and synaptic layers. An isolated PCNA+ cell in the inner nuclear layer (arrow) is an INL progenitor in the rod lineage. Nuclei are counterstained with DAPI (blue).
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