Figure 2.

In vitro angiogenesis assay of vascular and avascular chondrosarcoma tumor nodules. Vascular tumor nodules (TN), implanted in collagen gels throughout which capillary EC were dispersed, induced the concentration and alignment of capillary EC around the nodule (A) by day 3 in culture, in contrast to the lack of angiogenic response to avascular tumor nodules (B). When capillary EC as in A are labeled with fluoresceinated low density lipoprotein, the corona of EC around the vascular nodules is highlighted (C). To show the position of the vascular tumor nodule that is not fluorescent, the nodule in C is shown as a superimposed image taken with bright-field illumination. (Scale bar: A–C, 150 μm.)