Fig. 3. A wave of shh-GFP expression spreads through the GCL and INL independently of ath5 activity. All images are confocal sections of the retina, with anterior to the top. (A) Wild-type embryo double labeled for Zn5 protein (red) and shh-GFP expression (green) at 32 hpf. The expression of both markers has been initiated in the ventronasal sector. Note that some of the shh-GFP-expressing cells do not co-express Zn5, and are therefore amacrine cells (inset, arrowhead). (B) Wild-type embryo double labeled for Zn5 and shh-GFP at 57 hpf. Expression of both markers has spread through the retina. (C) ath5 mutant embryo double labeled for Zn5 (red) and shh-GFP expression (green) at 32 hpf. Note the absence of Zn5-expressing cells, while a small number of shh-GFP-expressing cells are already present (arrowheads). (D) ath5 mutant embryo double labeled for Zn5 and shh-GFP expression at 57 hpf. Note that shh-GFP expression has spread through both the GCL and the INL.