Fig. 1.

Fz2^−/−;Fz7^−/− embryos exhibit a severe defect in convergent extension and die at ~E10.5. (A-D) Fz2^+/+;Fz7^−/− mouse embryos are indistinguishable from wild type at all stages. Fz2^−/−;Fz7^−/− embryos arrest growth at ~E8.5; at E9.5 they fail to turn but are still alive as judged by the presence of a heartbeat. Unstained specimens are shown. (E) Quantification of convergent extension, as determined by the embryo length:width ratio, among Fz2^−/−;Fz7^−/− and littermate control (Fz2^+/− ;Fz7^−/− or Fz2^+/+;Fz7^−/−) embryos at ~E8.5. Error bars indicate s.e.m. (F-M) H&E-stained transverse sections (as indicated in M) of the thorax from control Fz2^+/+;Fz7^−/− embryos at E8.5 and E9.5 and Fz2^−/−;Fz7^−/− embryos at E8.5. At E8.5, the Fz2^−/−;Fz7^−/− embryo has an open neural tube and a symmetric heart, whereas the control has a closed neural tube and exhibits left-right heart asymmetry. Scale bars: 1 mm in A-D; 200 μm in F-L.