Muscling In

Cut through a bungee cord and you’ll see many elastic strands bundled together, flexing to give strength to the overall rope. Muscle is often described in a similar way – a bundle of parallel tube-like myofibrils stretching independently but at the same time, to contract or relax the muscle. Yet these simulations tell a slightly different story, based on scans of mouse muscles with an advanced scanning electron microscope. Instead of being entirely separate, stretchy regions called sarcomeres (measured between the vertical black bands) often form branches between neighbouring myofibrils – connected regions are highlighted in different colours. While this occurs to different degrees in cardiac muscle (top) compared to skeletal muscle (bottom), it suggests that mice muscles, and ours, may behave more like muscular meshes than bungee cords, raising new questions for how these structures are affected by age and disease.

Written by John Ankers

John Ankers

Writer

A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Image adapted from work by T. Bradley Willingham and colleagues
• National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
• Image originally published under a Creative Commons Licence (BY 4.0)
• Published in Nature Communications, July 2020