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A New Method for Fibroblast‐less Primary Skeletal Muscle Cell Culture by the Use of Hydroxyurea

A method was developed to suppress growth of fibroblasts in chicken and mouse primary skeletal muscle cell cultures. Addition of hydroxyurea to the culture medium at appropriate time and concentrations suppressed the proliferation of fibroblasts whereas leaving myotubes grow and differentiate. The most favorable time for the addition was soon after myotube formation. The optimal concentrations for our purpose ranged from 0.5 to 1.0 mM. In the presence of hydroxyurea at these concentrations, myotubes grew larger and well differentiated, whereas fibroblasts remained in the suppressed state. In chicken myotubes cultured with hydroxyurea, cross‐striations, spontaneous twitching and myosin heavy chain appeared as in myotubes without hydroxyurea. In mouse myotubes cultured with hydroxyurea, myosin heavy chain and dystrophin appeared, as in control myotubes.