Fig. 6. Effect of inhibition of periderm cell migration on cell death and fusion. After periderm cell labeling (green), palate shelves were put in contact and cultured in the presence or absence of 6 µM cytochalasin D for 10 hours. (A) When cytochalasin D was included in the medium, palate morphology showed the lack of epithelial triangles (et) and weak shelf adhesion. To detect cell death, palates were either stained in whole-mount with Acridine Orange (C; bright spots) or slices processed for the TUNEL technique (B; red). (B) Periderm cells of control palates died within epithelial triangles (yellow; see also Fig. 3), whereas those from cytochalasin D-treated palates did not reach the oral and nasal closures and did not die (green cells; arrowheads). (C) Specific reduction in cell death was observed in the mes of cytochalasin D-treated palates with a minimum effect in rugae (r). These experiments were repeated more than three times at least in triplicate for each condition. Scale bars: in A, 100 µm for A; in C, 500 µm for C.