Fig. 6. Rescue of spicule formation by expression of VEGF mRNA in sea urchin embryos injected with Mo-VEGF. (A) Co-injection of Mo-VEGF and VEGF mRNA into unfertilized eggs. (B-D) Phenotypes of 72-hour-old embryos treated as in A. (E) Localized ectopic expression of VEGF obtained by microinjection of Mo-VEGF into the egg, and VEGF mRNA together with a fluorescent lineage marker into one blastomere at the 8-cell stage. (F-K) 72-hour-old embryos treated as in E were split into two batches for (F-H) DIC and fluorescence microscopy, with the DIC/fluorescence signal superimposed to show spicule formation, or (I-K) immunolocalization of lineage marker (light red) and WMISH with a SM30 probe (brown); dispersed spherical red `dots' are microinjection artifacts.