Transverse section of the muscle of a mouse

Transverse section of the muscle of a mouse. On the left, the green staining reveals the expression of the GFP protein (Green Fluorescent Protein), under the control of the Pax3 gene, in the nucleus of a myosatellite cell. On the right, the blue staining marks all the nuclei. The red staining, on both images, marks the presence of the extracellular matrix protein, laminin, around the fibers. The capacity of skeletal muscles to undergo regeneration depends on skeletal muscle stem cells, called myosatellite cells. Upon muscle injury, myosatellite cells undergo activation, proliferate, differentiate and fuse with each other to form new fibers.