A cell that is commited to differentiating into a muscle cell. Embryonic myoblasts develop from the mesoderm. They undergo proliferation, migrate to their various sites, and then differentiate into the appropriate form of myocytes. Myoblasts also occur as transient populations of cells in muscles undergoing repair. [ http://www.ncbi.nlm.nih.gov/pubmed/21849021 GOC:tfm MESH:D032446 ]