Cadherins/genetics; Cardiovascular System/embryology; Gene Expression Regulation, Developmental; Amino Acid Sequence; Animals; Antigens, CD; Biomarkers; Brain/blood supply; Brain/embryology; Cadherins/biosynthesis; Calcium/metabolism; Cell Adhesion; Cell Aggregation; Cell Movement; Cells, Cultured; Cloning, Molecular; DNA, Complementary/genetics; Endothelium, Vascular/embryology; Endothelium, Vascular/metabolism; Fetal Heart/metabolism; Hematopoietic System/embryology; Hematopoietic System/metabolism; Humans; Intercellular Junctions/metabolism; L Cells; Mice; Molecular Sequence Data; Neovascularization, Physiologic/physiology; Organ Specificity; Recombinant Proteins/metabolism; Sequence Alignment; Sequence Homology, Amino Acid; Species Specificity; Transfection