Embryos from a strain expressing an alpha-tubulin::GFP fusion protein (gift of K. Oegema) were visualized by spinning-disk confocal microscopy. This allowed the visualization of 0.7 µm-thick optical sections and yielded well-resolved, individual microtubules. In this movie, both mid-plane imaging (left panel) and CIMS (right panel) are shown in the same embryo. The movie starts before pronuclear envelope breakdown and ends with cytokinetic furrow ingression. Anterior is at the bottom and posterior is at the top. Frames were captured every 5 sec and are played back at 12 frames/sec.

The residence time of microtubules at the cortex can be determined by imaging microtubules in a cortical plane. In such movies, individual microtubules can be seen as individual dots or short line segments of fluorescence, and their stability at the cortex can be quantified by measuring the time during which a single microtubule is present in the plane of focus. This movie starts at pronuclear envelope breakdown and ends with cytokinetic furrow ingression. Anterior is to the left and posterior is to the right. Frames were captured every 2 sec and are played back at 12 frames/sec.

Filled arrowheads point to various individual microtubules that enter and leave the plane of focus in these time-lapse images; empty arrowheads indicate the position of these microtubules just before and after they appear in the cortex.  Residence time at the cortex can be obtained by determining the time (bottom right, in sec) during which a given microtubule is visible at the cortex. Frames were captured every 2 sec and are played back at 6 frames/sec.