Fig. 1

Prdm13 expression in the Xenopus retina. a Whole-mount in situ analysis of prdm13 expression during embryogenesis, shown as lateral views of the embryo heads or as transversal retinal sections at the indicated stages. At stage 42, the in situ hybridization has been performed on retinal section. The brown colour is the retinal pigment epithelium. Dotted lines delineate the ciliary marginal zone (CMZ). b Stage 28/30 sections following prdm13 in situ hybridization (red) and EdU incorporation assay (green). Below are enlargements of areas delineated with dotted lines. White arrows point to prdm13 ⁺ /Edu⁻ cells while yellow arrows point to double labelled cells. c Schematic of a CMZ in the periphery of a Xenopus tadpole retina. d Stage 42 retinal section following prdm13 in situ hybridization (dark blue) and EdU incorporation assay (green). Since EdU labels cells that are in the S-phase during the 3-h EdU pulse, not all proliferative cells are labelled, in particular the slowly cycling stem cells. Panel on the right is an enlargement of the area delineated with dotted lines. Arrows point to double labelled cells. e Prdm13 fluorescent in situ hybridization (red) on stage 41 retinal section, counterstained with Hoechst to visualize nuclei (blue). Panel on the right is an enlargement of the white square. The white and yellow arrows point to prdm13 positive cells localized in the ganglion cell layer (GCL), and the outer part of the inner nuclear layer (INL), respectively. Dotted lines delineate the three nuclear layers. f Pie chart showing the distribution of prdm13 ⁺ cells among the ganglion cell layer (GCL, 1.3 ± 0.5%), the inner part of INL (87.8 ± 1.3%) and the outer part of the INL (10.9 ± 1.3%). Data are presented as mean ± SEM, n = 20 sections. g Quantification of the percentage of prdm13 positive cells among amacrine cells (defined by their localization in the inner part of the INL). Data are presented as mean ± SEM. Number of analysed sections is indicated in the bar. NR: Neural Retina, CMZ: ciliary marginal zone; RPE: Retinal Pigmented Epithelium, GCL: Ganglion Cell Layer, INL: Inner Nuclear Layer, ONL: Outer Nuclear layer. Scale bar represents 200 μm (whole mount), 100 μm (sections)