ELECTRON MICROSCOPY: NERVOUS: NERVE: Peripheral nerve. (EM-labeled); RCH/AMC1657, Myelinated and unmyelinated axons, endoneurium, one example of an axon in early stage of myelination, mouse tissue. 1-myelinated axons, 2-unmyelinated axons, 3-axon in early stage of myelination, 4-collagen of endoneurium, 5-S