Inhibition of COX-1 does not cause defect in somite formation or VEGF production. Vinculin staining, marker for intersomitic boundary, reveals normal somite formation in the trunk both in control group (A) and treated group (B). In the tail region, vinculin staining is overlayed on DIC image of the same area. It also reveals that somite formation of the tail is unchanged in control group (C) vs. treated group (D). Somites in the treated embryos produce normal amounts of VEGF (F), compared to the untreated group (E).