All moral rights asserted. Recolouring or alteration of the image is prohibited without permission. Coloured scanning electron micrograph (SEM) of a trigeminal ganglion neuron (nerve cell) grown in 12-hour primary culture conditions. The trigeminal nerve, or fifth cranial nerve supplies the face. At upper left is a Schwann cell, which secretes myelin, a fatty substance that insulates nerve fibres. Magnification: x500 when printed at 15 centimetres wide.