Multicellular Ca2+ transients at the tissue level. An embryo expressing R-GECO1.0 was imaged during neural tube closure. Images show a dorsal view of the presumptive anterior spinal cord region; anterior is to the top. Elapsed time (seconds) is shown at the top left. Frames were captured every 20 seconds using spinning-disk confocal microscopy. Movie frame rate: 8 frames/sec.