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Inhibition of Wnt signaling rescues Left-LHb neuronal identities in the lateral habenulae of SB-505124-treated catshark embryos. a–n Transverse sections of catshark stage 31 habenulae from SB-505124- (a–g) and SB-505124- + IWR-1-treated (h–n) embryos, after IHC with an antibody directed against β-catenin (β-catenin in red, DAPI-stained nuclei in blue) (a,h), HCR-FISH with territories of ScSox1 (b,i) and ScProx1 (c,j) in respectively yellow and cyan, ISH with probes for ScSox1 (d,k), ScProx1 (e,l), ScNtng2 (f,m) and ScKiss1 (g,n). Sections are shown at anterior (d,e,k,l) or medial (a–c,f–j,m,n) organ levels, dorsal to the top. (a) and (b,c) show sections of the same embryo, same for (d) and (e), (f) and (g), (h) and (i–j), (k) and (l), (m) and (n). (a1,a2) and (h1,h2) show magnifications of the territories boxed in (a) and (h), with β-catenin signals in red and DAPI signals in blue. A right isomerism is observed following SB-505124 treatment (a–g). Arrowheads in (h–n) point to bilateral LHb sub-territories showing a Left-LHb identity in embryos co-treated with SB-505124 and IWR-1. “n = “ in (a–n) refers to the number of embryos exhibiting the same phenotype as shown in the figure, over the total number of embryos analyzed, using the same detection method. o Schemes showing the experimental procedure used for pharmacological treatments and the resulting habenular phenotypes, with territories of nuclear β-catenin accumulation in red, territories of Left- and Right-LHb identity in yellow and blue respectively. Arrowheads point to bilateral LHb sub-territories in embryos co-treated with SB-505124 and IWR-1. Abbreviations: hc, habenular commissure; L, left; R, right; st., stage. Scale bar = 100 µm.
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