| |
Fig. 1. Position of the putative cardiac neural crest and experimental design to analyze its contribution to the cardiovascular system. (A) Diagram of a neurula stage Xenopus embryo (stage 17) viewed from the dorsal side (anterior to top), with outline of the segments of the neural crest (NC) ablated along the anteroposterior axis (1-3). (B-D) Stage 17 embryos with the region of the three ablated NC domains indicated. (E-H) In situ hybridization for the NC marker Sox10 in control and NC-ablated embryos at stage 25. (E) In control embryos, Sox10 is expressed within the four streams of the migrating cranial NC: the mandibular (a), hyoid (b), anterior branchial (c) and posterior branchial (d) NC. (F) After ablation of NC domain ‘#1’, the most anterior NC stream (a) is lost. (G) Ablation of NC domain ‘#2’ results in loss of the three most posterior NC streams, without affecting the more anterior mandibular NC stream (a). (H) After ablation of NC domain ‘#3’, all four streams of the migrating cranial NC form normally. (I-N) Position of the ablated/transplanted NC domain at stage 17 with respect to adjacent tissues. The presumptive otic placode (I-K) as revealed by Sox9 expression (arrows) is unaffected after NC ablation. The ablated NC domain spans a region extending from the first to the fourth somite (L-N) as revealed by MyoD expression (brackets). (O) Experimental design to analyze NC contribution to the cardiovascular system. Two-cell stage embryos were injected in the animal pole with mRNA encoding RFP. At stage 17, the RFP-labeled NC is transplanted onto the equivalent region of an unlabeled host embryo (NC graft). (P,Q) RFP-labeled NC graft at stage 17. (R-U) At stage 25, cells derived from the RFP-labeled NC graft are confined to the three most posterior streams of cranial NC (b, c and d), and completely overlap with Sox10 expression as seen in the whole embryo (R,T) and in sections (S,U). The line in R and T indicates the level of the sections shown in S and U, respectively. Scale bars: 100 μm. |
