Figure 7.

Figure 7. Wnt signaling is required for the regionalization of SDECs.

(A) FISH for meox1 (red) and antibody staining for a destabilized Wnt/TCF reporter line (green) show co-expression of GFP and meox1 within the somite. (B) Inhibition of Wnt signaling using the chemical inhibitor IWP2 from 2 ss to 15 ss results in decreased expression of axin2 and meox1 with a concomitant increase of the expression of etv2 by qRT-PCR. We observed a reduction in meox1 expression, although not statistically significant. All genes analyzed between Wnt inhibitor and control embryos, except meox1, showed a statistically significant difference (p<0.001, unpaired, two-tailed Student’s t-test; n=3.) (C–D’) Cross section of Tg(etv2.1:EGFP)^zf372 embryos treated with IWP2 from 2 ss to15 ss. wnt inhibition results in ectopic formation of Etv2:GFP⁺ cells within the somite (arrowheads). (C’,D’) enlargement of somite compartment (dashed lines). Notice LPM cells migrating under the sclerotome (arrows). (E–F’) IWP2 control and treated embryos. wnt inhibition results in decreased expression of meox1 by WISH, compared to control embryos. (E,F) Lateral view. (E’,F’) Dorsal view. s, somites; LPM, lateral plate mesoderm; SDECs, somite-derived endothelial cells.