Fig. 3. Expression of gfra1a, gfra2 and phox2b message in the enteric nervous system. Lateral views of the trunk of 48 hpf embryos, somites 1-11, with the yolk removed (A,B), and the trunk of 96 hpf embryos from somites 10-14 (C,D) that have been hybridized with riboprobes for gfra1a (A,C), phox2b (B) and gfra2 (D). (E) Transverse section taken through a 96 hpf embryo at the level of somite 14 that has been hybridized with probe for gfra1a. Arrows in A,B indicate gene expression in the gut tube. Arrows in E indicate enteric neurons expressing gfra1a message around the circumference of the gut tube. The broken white line in E indicates the border of the mucosa while the broken green line indicates the gut wall. (A-D) Anterior is towards the left.