Fig. 4. Modulation of RGC-derived Shh signalling causes transcriptional-dependent changes in growth cone morphology. (A,B) Axons and growth cones from DN (A) and VT (B) explants immunostained with antibodies against Shh (green) and counterstained with phalloidin (red). Individual channels in A',A'',B',B'' with overlays in A''',B'''. (C) Confocal images of VT (I-RGC) and DN (C-RGC) growth cones exposed for 30 minutes to PBS (control), Shh, SAG, cyclopamine or anti-Shh antibody. (D,E) Percentage of collapsed growth cones in DN and VT explants after activation or inhibition of Shh signalling in the presence or absence of actinomycin D (ActD) or cycloheximide (CHX). The number of growth cones analysed is indicated above each bar. ActD and CHX prevent the decrease in growth cone collapse induced by Shh or SAG. ^*P<0.05 (contingency table with Fisher's exact test). Scale bar: 25 µm in A,B; 20 µm in C.