Local cortical relaxation is observed after removal of myosin II from the cortex. (A and B) Myosin II-tagRFP-T (magenta) and PH-GFP (green) were simultaneously imaged every 0.77 s with a dual camera spinning disk confocal microscope. (A) The invagination of the plasma membrane marked with arrows was led by an internalizing myosin II particle. On the other hand, no myosin particle was found at the tip of another invagination (marked by arrowheads). See Video 5 for the temporal dynamics. (B) Some cytoplasmic particles (white arrowhead) showed the signals of both myosin II and the PH domain, while others showed exclusive accumulation of the myosin II (magenta arrowheads) or the PH domain (green arrowheads) signals. See Video 6 for the temporal dynamics. (C and E) Embryos expressing myosin II-tagRFP-T (magenta) and tubulin-YFP (green) were imaged by spinning disk confocal microscopy (every 1.7 and 1.8 s in C and E, respectively), and time series of the posterior (C) and the anterior (E) side of two representative embryos are presented. Red arrows indicate the myosin II particles that were detached from the cortex and traveled along a microtubule fiber toward the centrosome. (D and F) Line profiles of myosin II on the regions of the cell cortex indicated in C and E, respectively, are presented as kymographs. The particles marked with a red arrowhead were removed from the cortex. Following this, the flanking myosin peaks (blue arrows) were gradually separated from each other, indicating the local relaxation of the cortical actomyosin network.