| |
Fig. 2. RFP-labeled NC contributes to the aortic sac and arch arteries and is dispensable for outflow tract septation. (A-D) Cells derived from a stage 17 RFP-labeled NC graft populate the wall of the aortic arch arteries at stage 45 and never populate the outflow tract (OFT). B-D are a higher magnification of the boxed area in A. Ventral views, anterior to top. (E-H) Four views of the same Xenopus embryo showing that the RFP-positive cells form a very sharp boundary (arrowheads) and do not overlap with the myocardium muscle cells, as labeled with MF20 antibody. (I-L) At stage 48, RFP-labeled NC-derived cells are confined to the large arteries (LCC, left carotid canal; LPC, left pulmocutaneous canal; RCC, right carotid canal; RPC, right pulmocutaneous canal) as seen in the whole embryo (J) and in sections (K,L). (M-X) Transverse sections of stage 41 embryos showing Nkx2.5 and Sox8 expression in control and manipulated embryos. (M-N) In control embryos, Nkx2.5 is expressed throughout the myocardium [outflow tract and ventricle (V)], whereas Sox8 is confined to the spiral septum (arrows). Sox8 is also detected in the NC-derived head mesenchyme (asterisks). (O-P) NC ablation does not prevent outflow tract septation as revealed by Sox8 expression (arrows). These embryos lack the aortic sac, resulting in a dorsal expansion of Nkx2.5. (Q-T) The RFP-labeled NC-derived cells are detected in the aortic sac and arch arteries (arrowheads) but not in the spiral septum of the outflow tract (arrows). U-X are higher magnification views of Q-T. Scale bars: 100 μm. |
