In neuroscience, the axolemma (from Greek lemma 'membrane, envelope', and 'axo-' from axon[1]) is the cell membrane of an axon,[1] the branch of a neuron through which signals (action potentials) are transmitted. The axolemma is a three-layered, bilipid membrane. Under standard electron microscope preparations, the structure is approximately 8 nanometers thick.[2]