Abstract
Myelin provides physical, neurotrophic, and metabolic support for axonal integrity. The thickness of CNS (central nervous system) myelin sheath is usually < one micrometer, which is under or near the detection threshold of the conventional light microscopy. Here, we present a high-resolution transmission electron microscopy-based protocol to assess myelination at the ultrastructural level. We describe sample preparation from mouse tissue, followed by electron microscopic imaging and CNS myelination analysis. This protocol is also useful for analyzing murine PNS myelination. For complete details on the use and execution of this protocol, please refer to Wang et al. (2021).