Macrophage white blood cell. Coloured transmission electron micrograph (TEM) of a section through a macrophage in skin tissue, showing the nucleus (brown, round) and numerous lysosomes (dark purple). Lysosomes contain enzymes for digesting foreign particles. Macrophages are a type of large white blood cell that recognise foreign particles and phagocytose (engulf and digest) them. Magnification: x6000 when printed 10 centimetres wide.