sDll4 induces vessel response but lacks perfusion in murine Matrigel assay. (A) Matrigel was injected subcutaneously into Balb/C nu/nu mice. After 6 days, plugs were removed and processed in paraffin. Individual sections were stained with H&E, and representative photographs at × 20 magnification from triplicate plugs in 2 independent experiments are shown. (B) Matrigel plugs were stained for PECAM. Photomicrographs were taken with an Olympus BX51 microscope with an Olympus UPlan FL ∞, 0.17 20×/0.5 NA dry objective mounted with a Retiga 2000R camera (QImaging, Burnaby, BC, Canada) and processed with Image-Pro Plus 6.0. Quantitation of vascularized area averaged (± SEM) from all plugs (Scion Image software; Scion, Frederick, MD) in bar graph. *P < .05 compared to no growth factor.