Scientists have produced the first high-resolution 3D image of the sarcomere, the basic contractile unit of skeletal and heart muscle cells, by using electron cryo-tomography (cryo-ET). The international team, led by Stefan Raunser, Director at the Max Planck Institute of Molecular Physiology in Dortmund, in collaboration with Mathias Gautel at the King’s College in London, describes the findings this week in the online version of the journal Cell. Cryo-ET capability of imaging structures directly in frozen muscle cells could translate into future medical treatments for muscle diseases and a better understanding of the aging process.