Fig. 2.

Vascular defects in Fz2^−/−;Fz7^−/− embryos. (A-D) Fz2^−/−;Fz7^−/− mouse embryos are still alive at E10.5 as judged by the presence of a heartbeat, but the yolk sac shows extensive pooling of blood. Unstained specimens are shown. (E-H) Fz2^−/−;Fz7^−/− yolk sac vasculature fails to differentiate into well-organized larger and smaller vessels (compare E and F; Pecam 1 immunostaining). Pooling of red blood cells in the dense capillary network is seen in transverse section (compare G and H; Toluidine Blue staining). (I,J) The Fz2^−/−;Fz7^−/− embryo vasculature remains rudimentary at E9.5. Scale bars: 1 mm in A-D; 500 μm in E,F,I,J; 100 μm in G,H.