BB creatine kinase and myogenic differentiation. Immunocytochemical identification of a distinct precursor compartment in the chicken skeletal myogenic lineage.

Antisera specific for the B monomer of creatine kinase (B-CK), the M monomer of creatine kinase (M-CK), and muscle-specific myosin heavy chain (MHC) were used to investigate the biochemical characteristics of individual cells in primary myogenic cultures. Through the use of immunocytochemical techniques, in conjunction with 3H-thymidine autoradiography, it was determined that (1) all of the terminally differentiated myoblasts contained B-CK in addition to M-CK and MHC, (2) none of the cycling cells contained M-CK or MHC, (3) a fraction (7.5%) of the cycling cells contained B-CK, and (4) the cycling, B-CK positive cells divided once, and only once, and produced two terminally differentiated myoblasts. These results indicate that myogenic precursors in vitro are a phenotypically heterogeneous cell population and that the appearance of B-CK in cycling myogenic cells is a biochemical manifestation of a distinct precursor compartment in the chicken skeletal myogenic lineage.