In this movie light-sheet microscopy has been used to visualize muscle fibers and alpha motor neurons in muscle and Eva Hedlund, professor in Neurobiology at the Karolinska Institute, explains how these muscles function and how they are affected by the neurodegenerative disease amyotrophic lateral sclerosis (ALS).

The skeletal muscle is one of our largest organs and its contraction make us able to move our body. Myocytes are the major cell type in the muscle and depending on what type of the protein myosin they contain they will form slow fibers needed to keep our posture when we stand still or fast fibers needed to run.

The contractions of muscle fibers are controlled by a network of alpha motor neurons and in ALS these begin to degenerate, which leads to weakness and paralysis. 3D visualization of the interaction between alpha motor neurons and the muscle fibers in health and disease progress may help in understanding how to prevent the breakdown of muscle fiber in ALS.

Link to movie

Link to short version movie