Credit: STEVE GSCHMEISSNER / SCIENCE PHOTO LIBRARY

Caption: Macrophage engulfing a nerve cell. Transmission electron micrograph (TEM) of a section through a macrophage white blood cell (yellow) that has engulfed a nerve cell (neuron, centre, blue) damaged by multiple sclerosis (MS). Nerve damage is a typical feature of MS. Macrophages are a type of large white blood cell that recognise foreign particles and damaged cells and phagocytose (engulf and digest) them. Magnification: x6000 when printed 10 centimetres wide.