Occurrence of C-type apoptotic cells before and during the midline fusion. Time-lapse video of apoptosis before and during the midline fusion in MHNP closure, as shown in Fig. 3 E. Boundary cells underwent C-type apoptosis (judged by immediate cell fragmentation after caspase activation) before and during sealing of the midline. Some of the cells undergoing C-type apoptosis in the midline were marked first by yellow arrowheads and after caspase activation by cyan in the ECFP image (bottom). Caspase activation is indicated by the V/C (1.0–0.5) using pseudocolor (top). Live imaging was performed on an inverted confocal microscope (TCS SP5). Frames were taken at intervals of 4 min for 12 h.
