Electron microscopic evidence for mural cell recruitment after PlGF treatment. (A-B,D) Transmission electron microscopic images of vessels newly formed upon PlGF gene transfer. (A-B) Microvessels are surrounded by 2 layers of (endothelial and pericyte) basal laminae (arrowheads). (B) Capillaries are in intimate contact with the astrocytes (As); arrow points to tight junction between 2 endothelial cells. (C) SMA-positive vessels (arrow) after hPlGF gene transfer, for quantification. (D) Quantification of SMA-positive vessel density from immunostainings. *P < .05; **P < .01; and ***P < .001 when compared with HSA control; error bars show SD. (E) Arterioles are ensheathed in a single layer of VSMC. EC, endothelial cell; Ne, neuron; Pe, pericyte; RBC, red blood cell; VSMC, vascular smooth muscle cell. Scale bars: A-B,E, 1 μm; C, 200 μm.