BDNF expressed ectodermal animal cap grafts stimulate mandibular trigeminal axon arborisation. (A) Diagram of the in vivo cement gland substitution assay. (B) Successfully grafted embryos were identified by GFP expression. (C) Neither GFP+ nor (D) NT3+ grafts stimulated trigeminal axon arborisation or growth onto the grafts. (E) BDNF+ graft stimulated axon terminal arborisation onto the graft. AC = animal cap, CG = cement gland, Asterisk = graft.