Merging of Muscle Cells

What am I looking at?

This video shows cultured mouse skeletal muscle cells undergoing fusion. The nuclei are labeled in green, and the cell bodies are labeled in red. You can see fusion of hundreds of myoblasts to form multinucleated myofibers.

Biology in the Background

Muscles are formed by the merging of many small myoblasts into larger myofibers. This fusion of mononucleated myoblasts with a single nucleus into multinucleated myofibers with multiple nuclei is an essential step to build skeletal muscle during muscle development and to repair skeletal muscle after injury. In humans, a single myofiber can be created from hundreds or even thousands of muscle cells resulting in a single mature cell with the corresponding number of nuclei.

Videos like this one can provide insight into how muscles develop and repair themselves. This information could be the foundation for future research on muscular disease, healing, and even fitness.  

The mouse myoblasts can grow up to 30 micrometers across, or roughly 2.5 times smaller than the width of a human hair. Mature myofibers can be 100 micrometers across (slightly larger than the width of a human hair) and can grow up to 3 centimeters in length (about 1.5 times larger than the width of your thumbnail). In humans these myofibers can reach up to 42 centimeters, traveling almost the entire length of the thigh muscle.

Technique

This video was created using confocal microscopy.