RT Journal Article SR Electronic T1 MyelTracer: A Semi-Automated Software for Myelin g-Ratio Quantification JF eneuro JO eNeuro FD Society for Neuroscience SP ENEURO.0558-20.2021 DO 10.1523/ENEURO.0558-20.2021 VO 8 IS 4 A1 Tobias Kaiser A1 Harrison Mitchell Allen A1 Ohyoon Kwon A1 Boaz Barak A1 Jing Wang A1 Zhigang He A1 Minqing Jiang A1 Guoping Feng YR 2021 UL http://www.eneuro.org/content/8/4/ENEURO.0558-20.2021.abstract AB In the central and peripheral nervous systems, the myelin sheath promotes neuronal signal transduction. The thickness of the myelin sheath changes during development and in disease conditions like multiple sclerosis. Such changes are routinely detected using electron microscopy through g-ratio quantification. While g-ratio is one of the most critical measurements in myelin studies, a major drawback is that g-ratio quantification is extremely laborious and time-consuming. Here, we report the development and validation of MyelTracer, an installable, stand-alone software for semi-automated g-ratio quantification based on the Open Computer Vision Library (OpenCV). Compared with manual g-ratio quantification, using MyelTracer produces consistent results across multiple tissues and animal ages, as well as in remyelination after optic nerve crush, and reduces total quantification time by 40–60%. With g-ratio measurements via MyelTracer, a known hypomyelination phenotype can be detected in a Williams syndrome mouse model. MyelTracer is easy to use and freely available for Windows and Mac OS X (https://github.com/HarrisonAllen/MyelTracer).