Fig. 8. Neural crest formation can be experimentally uncoupled from neural plate patterning. (A-D) Injected embryos were analyzed around stage 18 and stained for Slug expression. (A) Control embryo. (B) XFD injections result in gastrulation defects and loss of most Slug staining. (C) NFz8 injections most often produce an abnormally shaped neural plate, gastrulation defects and reduced Slug expression. (D) dnFGFR4a-injected embryos show severe gastrulation defects but still present a strong Slug staining (the right hand embryo is shown in side view). (E,F) Similar injections were analyzed at stage 11.5-12 for Otx2 expression. Otx2 labels the area anterior to the neural crest-forming regions. It is found further from the blastopore as development proceeds (blue bars measure the distance between the posterior part of the Otx2 domain and the blastopore; anterior is indicated by the red star). (E) Stage 11.5 (left) and stage 12 (right) control embryos. (F) NFz8-injected embryos show a strongly reduced posterior neural crest-forming domain. (G) dnFGFR4a injections result either in normal sized posterior domain (left) or strongly reduced ones (right). Both types of embryos will show a strong Slug expression at stage 18 (D). Red stars indicate anterior.