Endothelial expression of RAF1S259A causes defective arterial morphogenesis. (A) Dark field images of posterior E12.5 yolk sacs with embryo inside. Higher magnification images of the areas highlighted in the square are shown in the lower panels. Posterior vitelline arteries (a) and veins (v) are indicated with arrows. Bar represents 2 mm. (B-C) Whole mount immunofluorescent staining of E12.5 yolk sacs. Arteries are stained with the arterial marker CX40. Bars represent 100 μm (B) and 50 μm (C). (D) Quantification of posterior vitelline artery size as shown in (C). The diameter of the 2 major branches of posterior vitelline arteries in each yolk sac was quantified and averaged to represent that of 1 embryo. Mean ± SEM. n = 5 embryos. (E) Whole mount immunofluorescent staining of E14.5 skin. Bar represents 100 μm. a, artery; v, vein. (F) Whole mount immunofluorescent staining of E14.5 skin. Bar represents 100 μm. (G) Quantitative analysis of arterial branching in skin of E14.5 embryos as shown in (F). Branch points of 4 major artery trees in each dorsal skin of an embryo were counted and averaged to represent that of one artery tree. Mean ± SEM. Control, n = 14 embryos; S259A, n = 13 embryos.
