(A) Brain and lung samples collected from animals perfused with 20 µm fluorescent beads through the carotid artery. Beads were detected in all brain samples, but only Alk1-floxed mice injected with Ad-Cre and AAV-VEGF had a significant amount of beads in the lung. A few beads were detected in the lungs of control mice injected with AAV-VEGF.
(B) Latex-perfused brain. Latex (blue) presented only in cerebral arteries of Alk12f/2f/ROSA26(+/creER) mice treated with tamoxifen that had Alk1 gene deleted globally (left). Alk1-floxed mice that received intracerebral injection of Ad-Cre and AAV-VEGF had an increase of vascular density at the injection site (arrow, middle image). At higher magnification (right), vessels are enlarged and tortuous with a fistula between arteries and veins. Scale Bar = 100 µm.
(C) Two color latex perfusion shows direct connections of cerebral arteries (blue) and veins (green) (arrows). Scale Bar = 100 µm.