A dorsomedial portion will develop into the myotome . The myotome will form the skeletal muscles. Finally the most dorsolateral portion is called the dermatome . The dermatome will give rise to the dermis of the skin and the subcutaneous tissue. The differentiation of the myotome includes a stage where the cells are loosely arranged into what is called the mesenchyme .
Mesenchymal cells are stellate cells that are embedded in a semifluid intercellular substance.
Mesenchymal cells develop into both muscle cells and connective tissue cells, and therefore are also found within the sclerotome. Those mesenchymal cells that will develop into muscle elongate and become spindle shaped, multinucleated cells that contain peripherally located myofibrils. These cells are called myoblasts . As development continues the nuclei of these cells migrate peripherally and most of the central cytoplasm becomes filled with myofibrils. Muscle development is largely controlled by the connective tissue that surrounds these cells.