Fig. 7. BMP signaling is required locally in endoderm for epibranchial neurogenesis. Lateral views, anterior to the left. In situ hybridization for phox2b mRNA labels epibranchials at 48 hpf in all panels, whereas biotinylated-dextran injected into the donor labels transplanted cells (brown). (A) Wild-type pattern of phox2b expression in a control embryo that received a large graft of cas-injected endodermal cells. Similar results were obtained with tar*. (B-F) Wild-type hosts that received transplants of donor cells co-injected with tar*/dextran and either nog mRNA (B-D) or bmp2b and bmp5 MOs (E,F), which disrupt epibranchial formation (arrows). (G) phox2b expression in a cas mutant showing lack of epibranchials at 48 hpf. (H-L) Transplantation of tar*/nog (H,I) tar*/bmp5MO (J), cas/bmp2b/5MO-injected (K) or tar*/bmp2b/5MO-injected (L) endodermal pouches (arrows) fails to rescue epibranchials in cas mutants. Scale bar: 50 µm.