Detection of myosin heavy chain mRNA during myogenesis in tissue culture by in vitro and in situ hybridization.

A cDNA copy of purified chick embryonic skeletal myosin heavy chain mRNA (MHC mRNA) distinguished between myogenic and nonmyogenic cells compared by in vitro and in situ hybridization. The majority of cells in replicating mononucleate myogenic cell cultures contained no detectable MHC mRNA. Among the earliest cells to contain MHC mRNA were cells engaged in mitosis. A relatively large amount of MHC mRNA was found in postmitotic monucleate cells and myotubes, and we observed nucleolar localization of MHC mRNA in these cells.