Fig. 6.

Extravasation of ICG into the interstitial space surrounding tumour vasculature. a Immunofluorescence staining (original magnification, 40×) of LLC tumour sections demonstrating ICG accumulation at different doses (1, 2.5 and 5 mg/ml; pseudo-red colour) surrounding CD31⁺ tumour capillaries (green, white arrowheads) of LLC tumours 30 s after intravenous administration. Nuclei were counterstained with 4′,6-diamidino-2-phenylindole (blue). Scale bar: 20 μm. b Confocal fluorescence imaging of LLC tumour sections (original magnification, 60×). Note that ICG (5 mg/ml) was distributed extensively in the tumour cells, but not in CD31⁺ tumour capillaries (yellow arrowheads)