Fig. 4. Neural fold apposition in Xdd1 expressing embryos. See also Movies 1-4 at http://dev.biologists.org/supplemental/ (A) Control embryo at stage 16. (B) Xdd1-injected closed-NT embryo at stage 16. (C,D) Xdd1-injected open-NT embryos at stage 16. (a'-d'). Same embryos as in A-D shown at stage 23. (E) Plot of average distance between neural folds for control and Xdd1 closed-NT embryos. (F) Plot of average distance between neural folds for control and Xdd1 open-NT embryos. (G) Plot of rate of neural fold apposition (change in average distance between neural folds/time) for control, closed-NT, and open-NT embryos at mid- and late-neural stages. Data shown in E-G are mean±s.d. from six different movies on different days (control n=9; open-NT n=15; closed NT n=9). (H) Plot of LWR of the AP axis of each embryo in A-D; there is a strong correlation between axis elongation and success of NT closure.