Pax7 Is Required for the Myogenic Specification of CD45⁺:Sca1⁺ Cells

<div><p>(A) Flow cytometric analysis of cell suspensions derived from uninjured and regenerating wild-type and <i>Pax7</i><b>^−/−</b> muscle (4 d after ctx injection) showed an increased proportion of CD45⁺ cells in <i>Pax7</i><b>^−/−</b> samples.</p> <p>(B and C) Pax7 protein was expressed in approximately 6%–10% of CD45⁺:Sca1⁺ cells purified from regenerating <i>Pax7^+/−</i> muscle.</p> <p>(D–K) MyoD (D and E) and Desmin (F and G) were induced in CD45⁺:Sca1⁺ cells from regenerating <i>Pax7^+/−</i> but were not expressed in CD45⁺:Sca1⁺ cells from regenerating <i>Pax7</i><b>^−/−</b> muscle (H–K).</p>