Myoblast

A myoblast is a type of stem cell that exists in muscles. Skeletal muscle cells are called muscle fibers and are made when myoblasts fuse together; muscle fibers therefore have multiple nuclei.

Myoblasts that do not form muscle fibers differentiate into satellite cells. These satellite cells remain adjacent to a muscle fiber, separated only by its cell membrane and by the endomysium (the connective tissue investment that divides the muscle fascicles into individual fibers).