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 (pale brown) and inner nucleolus (dark brown). 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.