Liver macrophage cells. Coloured scanning electron micrograph (SEM) of liver macrophages, also known as Kupffer cells. Macrophages are a type of large white blood cell that recognise foreign particles and old blood cells and phagocytose (engulf and digest) them. The cytoplasmic extensions are used for locomotion within the tissues. Magnification: x3000 when printed at 10 centimetres wide.