File:Embryogenesis-of-the-First-Circulating-Endothelial-Cells-pone.0060841.s003.ogv

English: A wide-field recording of a Tie1-H2B-YFP embryo from HH7 to HH14. The fluorescence signal shows numerous examples of endothelial cells moving in an abrupt saltatory fashion compared to the majority of ‘non-motile’ cells situated in vascular tubes. An observer perceives the motion as a Tie1-YFP cell (nucleus) ‘jumping’ to a new location within one time-lapse frame. Such motion requires a displacement speed that is far greater than cell autonomous (‘self-propelled’) locomotion. The saltatory behavior is best visualized by advancing the recording frame-by-frame using the QuickTime™ software controls. Perhaps more importantly, there are numerous examples where a Tie1-YFP cell is present in one frame and is lost from view during the next recording cycle, this event is operationally defined here as “rapid displacement behavior”. Numerous examples are visible in the ROI denoted by the white box. We interpret these empirical data as evidence that a given cell-of-interest entered circulation and was swept away by fluid flow. Tie1-YFP cellular aggregates also display rapid displacement behavior (white box). In a variation of rapid displacement behavior cell clusters are observed shedding from the luminal face of large vessels such as aortic vessels (circles 12.37 h–24.21 h). Furthermore, throughout the later time points there are scores of Tie1-YFP clusters circulating freely through the great vessels (22–29 h recording interval). The DIC and fluorescence Movie S2 frames are montages of eight XY image fields. The recording rate is approximately 7.5 frames per hour (fph) or 8 min between frames. The compression algorithms used in creating this movie result in a loss of resolution compared to the native image files (see Methods). Mag bar = 100 µm.