Fig. 3

Imaging sequences and schematics showing the basic spatial wave types. The color scales indicate luminescent flux in [(photons per pixel per sec) x 10^-2]. (Bar = 200 μm.) The red asterisks and PM in the schematics indicates the dorsal midline pacemaker or wave initiating site. (A) Sequence of 30-sec data integrations showing a bidirectional propagating calcium wave occurring at about 90% epiboly (Fig. 2A, asterisk). Data from this wave are plotted in matching time intervals in Fig. 2D. The end of the interwave interval is shown in the first frame, the prewave pulse is in the second frame, and the dorsal pacemaker pulse and propagating wave are in the next four frames. The schematic shows a generalized bidirectional wave oriented as in the imaging frames. Blue dashed arrows indicate epibolic movements. (B) A unidirectional wave that required about 5 min to circumnavigate the blastoderm margin is shown in sequential 60-sec integrations starting with the pacemaker pulse. (C) During somitogenesis, periodic radial calcium wave fronts spread from the tail bud region. The images in C represent a 120-sec integration window moving along the data stream in 20-sec steps at the 10-somite stage. Time-lapse movies of these imaging sequences are shown in the supplemental material on the PNAS web site.