Fig. 4. Abnormal node morphology in Sufu^-/- mouse embryos. Immunofluorescent staining with anti-acetylated tubulin antibodies was performed on wild-type (A,D) and Sufu^-/- (B,C,E,F) mouse embryos at 7.75 dpc. In wild-type embryos, the node is composed of tightly packed, monociliated cells and is roughly the shape of an isosceles triangle with the base oriented toward the posterior (yellow outlining in A). The cytoskeletons of cells surrounding the node are visible in A, which shows the normal size difference between node cells and their larger neighbors. Variable node dysmorphology (B,C) is seen in the Sufu^-/- embryos. Five out of five 7.75 dpc Sufu^-/- embryos examined displayed abnormal node architecture, ranging from mild changes in the shape of the node to irregular distribution of nodal cells. B shows an ovoid to diamond-shaped node in a Sufu^-/- embryo. C shows three or more separate irregular islands of nodal tissue with flattened cells, atypical for a normal node, visible between the islands. (D-F) Higher magnification views show normal monocilia in a wild-type embryo (D), and in Sufu^-/- embryos (E,F). Boxes in A-C outline the areas shown at higher magnification in D-F. All panels are oriented with anterior at the top and posterior at the bottom. Ant, anterior; Post, posterior. Scale bars: 50 µm in A-C; 10 µm in D-F.