Fig. 1. Components of the Shh signalling pathway are differentially expressed in I-RGCs and C-RGCs. (A,B,F-K) In situ hybridisation analysis of coronal sections from E14.5 mouse embryos as indicated. (C-E) Similar sections from Shh::GFPCre/+ E14.5 embryos double labelled for GFP (green) and Zic2 (red); overlay in yellow. Shh mRNA localises to most of the RGC layer but is absent from the ventrotemporal crescent (VTC), where only rare Zic2/GFP⁺ cells are observed (arrows in A,C-E). Ptc2 (F,H) and Boc (G,I) are expressed in the VTC (thick dotted line) but not in C-RGCs (thin dashed line). Ptc1 (B) and Hip1 (J) are distributed throughout the neuroepithelium and Gli2 (K) localises to the RGC layer. cRGC, contralateral projecting RGCs. Scale bar: 200 µm in A,B,F,G,J,K; 30 µm in C-E; 35 µm in H,I.