Blood vessel in cancerous tissue. Coloured scanning electron micrograph (SEM) of a freeze-fractured tissue sample from an adenocarcinoma, a type of cancer. At lower centre is a blood vessel, with blood cells visible in the lumen. These include a lymphocyte (yellow), some platelets (grey) and erythrocytes (red blood cells). The cells of the wall of the blood vessel, the endothelium, are also visible, with the cell nucleus (dark red) visible in three of these cells. In the surrounding cancer cells, the nuclei are shown in red. Connective tissue fibres (grey) are seen between the cells. Magnification: x2700 when printed at 10 centimetres across.