Immunohistochemical staining of RESDECs demonstrating endothelial cell features. (A-D) von Willebrand factor staining demonstrates positive staining only in RESDECs and HUVECs. (A) RESDECs; original magnification, × 100. (B) HUVECs; original magnification, × 40. (C) MEFs; original magnification, × 100. (D) Undifferentiated rhesus ES cells; original magnification, × 100. (E-G) Uptake of acetylated LDL demonstrates specific staining of RESDEC and HUVEC. (E) RESDECs; original magnification, × 100. (F) HUVECs; original magnification, × 40. (G) MEFs; original magnification, × 100. (H) Binding to ulex europaeus agglutinin-1 to RESDECs grown as tubes in Matrigel; original magnification, × 100.