Peripheral nerve. Light micrograph of a peripheral nerve and its myelinated axons (nerve fibres). This is an intact nerve (not sectioned), stained with dyes. The nerve fibres stain black-brown, with connective tissues staining green. Myelin sheaths are the black margins along the central axons. The regular sites of narrowing of the myelin sheath are the nodes of Ranvier. The region between nodes where the nerve fibre are sheathed in myelin produced by individual Schwann cells. Nerve impulses travel very fast along myelinated nerves by jumping from one myelin sheath to the next. Magnification: x147 when printed at 10 centimetres across.