The participation of individual VEGFR2+ endothelial cells to the initial formation of tumor vascular network.

<p>Individual VEGFR2+ endothelial cells located at the center of B16 xenograft (indicated by arrow, A). The region in white dotted box was magnified in B. With the tumor growth (C), individual endothelial cells (arrows) increased its length and fused with angiogenic sprouts (arrowheads). (D) Histogram represents (n = 12, p<0.05) the percentage of endothelial columns that originated from the individual ECs or the angiogenic sprouts. Scale bar, 100 µm (A, C) or 50 µm (B).