Nerve fibres. Light micrograph of a section through a bundle of myelinated axons. Axons are nerve cell processes that transmit nerve impulses away from the cell body. They eventually terminate in a synapse with another nerve cell or with an effector organ, for example a muscle cell where the impulse causes a response. Myelinated axons have a myelin sheath (dark blue) that is produced by associated Schwann cells. The myelin sheath causes impulses to be transmitted faster than in unmyelinated axons. Magnification: x430 when printed 10cm wide.