Figure 2.

Transmission electron microphotographs of representative tumour microvessels. (a) Microvasculature from the control tumour showing intact vascular elements, i.e. endothelial cells, mural cells and basement membrane. (b) Abluminal processes emerging from a vascular endothelial growth factor (VEGF)-transfected tumour vessel (arrowheads). (c) Luminal processes originating from the inside wall of endothelial cells of a VEGF-transfected tumour vessel (arrows). (d) A characteristic microvessel observed in the VEGF-transfected tumour. Vascular endothelium was elongated with a plump nucleus, suggesting endothelial cell activation. Endothelial fenestrations (arrow) and a disruption (arrowhead) were specific to the VEGF-transfected tumours. (e) Higher magnification of the endothelial fenestrations with diaphragms (arrows). Bm, basement membrane; Ec, erythrocyte; En, endothelial cell; Mc, mural cell; Pl, platelet. Scale bars: 1 µm (a–d); 0.5 µm (e).