Hippocampus neuron. Coloured transmission electron micrograph (TEM) of a section through a neuron from the hippocampus, a structure in the brain responsible for long-term memory. Neurons are responsible for passing information around the central nervous system (CNS) and from the CNS to the rest of the body. The neuron consists of a cell body with a large nucleus (brown) and inner nucleolus (white). The single nerve fibre (axon, right) transmits nerve impulses away from the cell body. The surrounding material is the brain's grey matter. Magnification: x1800 when printed at 10 centimetres wide.