alphavbeta3 integrin-dependent endothelial cell dynamics in vivo.

A major challenge confronting developmental cell biologists is to understand how individual cell behaviors lead to global tissue organization. Taking advantage of an endothelial cell-specific marker and scanning time-lapse microscopy, we have examined the formation of the primary vascular pattern during avian vasculogenesis. Five types of distinguishable endothelial cell motion are observed during formation of a vascular plexus: (1) global tissue deformations that passively convect endothelial cells; (2) vascular drift, a sheet-like medial translocation of the entire vascular plexus; (3) structural rearrangements, such as vascular fusion; (4) individual cell migration along existing endothelial structures; and (5) cell process extension into avascular areas, resulting in new links within the plexus. The last four types of motion are quantified and found to be reduced in the presence of an alphavbeta3 integrin inhibitor. These dynamic cell motility data result in new hypotheses regarding primordial endothelial cell behavior during embryonic vasculogenesis.