The onset of sox4b expression is delayed in ascl1b morphants and is restricted to neurod1 expressing cells. Ventral views with the anterior part to the left of double fluorescent WISH showing expression of sox4b and neurod1 at 12 hpf (A-F), 13 hpf (G-L) and 17 hpf (M-R) in control and ascl1b morphants. The domain occupied by sox4b+ and neurod1+ cells was reduced respectively 3.3- and 2.6-fold in the Mo-ascl1b at 17 hpf. The arrows point to a cell expressing sox4b and neurod1 while the arrowheads points to a cell expressing only sox4b. Z-plane confocal images. Scale bars : 50 µm hpf, hours post fertilization; WISH, whole-mount in situ hybridization.