There is evidence for two basic and distinct mechanisms of early blood vessel formation: vasculogenesis forms endothelial cords and tubes in place by the cohesion of angioblasts and angiogenesis forms new vessels by the migration of sprouts off of preexisting vessels. A major unsettled issue in how both of these mechanisms establish embryonic vascular pattern is the extent and guidance of the directed migration of angioblasts. Dr. Poole's hypothesis is that glycoproteins of the extracellular matrix, not diffusible angiogenic factors, guide the migrations of angioblasts which are important in establishing the initial vascular pattern. He proposes to use blockages and transplantations to determine regions of angioblast migration and the timing of these migrations. He will transplant fragments of quail mesoderm into chick embryos to examine angioblast migratory capacity in both normally vascular and avascular zones. He will use specific antibodies to map the distributions of fibronectin, laminin and tenascin during early vascular development. He will use peptides and antibodies to perturb the adhesion of angioblasts to extracellular matrix. %%% Vascular development is a crucial early event in the development of the embryo. Clarifying the roles of cell migration and cell- substrate adhesion in vascular development provides information of significance both to basic developmental biology and the study of abnormal vessel growth and proliferation.
