Coloured scanning electron micrograph (SEM) of the internal surface of a PICC (peripherally inserted central catheter) line with red blood cells a white blood cell (purple) and a meshwork of platelets, their processes, and fibrin. A PICC line is used to give chemotherapy or other treatments such as liquid nutrition. It is a long, thin, hollow, flexible tube, threaded along a vein until the tip is in a large vein just above the heart. The inside of the line can sometimes become partly or completely blocked. Magnification: x3000 when printed at 10 cm wide.