All moral rights asserted. Recolouring or alteration of the image is prohibited without permission. Differential interference contrast light micrograph of trigeminal ganglion neurons (dark) grown in 12 hours primary culture conditions. The trigeminal nerve, or fifth cranial nerve supplies the face. Also seen are Schwann cells (bright), which secrete myelin, a fatty substance that insulates nerve fibres. Magnification: x400 when printed at 15 centimetres wide.