Insufficient movement of the dorsal ridge of the neural plates by inhibition of apoptosis ex utero. Comparison of closure I between control (apaf-1^+/−) and apoptosis-deficient (apaf-1^−/−) embryos by live-imaging analysis. Caspase activation is indicated by the V/C (1.0–0.5). (A) Flipping of dorsal ridges (arrows in apaf-1^+/−) was severely reduced in apaf-1^−/− embryos. Few apoptotic cells (blue cells in apaf-1^+/−) were seen in the apaf-1^−/− embryos. t represents the imaging duration (minutes). (B) Bending of the neural plate was severely reduced in apaf-1^−/− embryos in prospective midbrain regions. Surface ectoderm is colored yellow in ECFP images in ii (magnified images of the boxed areas on the left). Neither bending nor apoptosis occurred (i and ii). (iii) Reconstituted transverse (XZ) sections from 4D datasets at r2, shown by yellow lines in i. Bars: (A and B [i, and iii]) 100 µm; (B, ii) 50 µm.