Figure 3

Luciferase signal colocalizes to CD68+ and CD11b + immune cells in Cox2 ^FLuc/+ DMD ^−/− muscle cross sections. Cross sections of Cox2 ^FLuc/+DMD^−/− mouse quadriceps, fluorescently labeled with antibodies to luciferase ((A) and (D), in green), CD68 (red) (B), developmental myosin heavy chain (dMHC) (red) (C), and CD11b (red) (D). (A), (B), and (C) are serial sections in which asterisks indicate the same fibers in each of the three sections. The yellow arrowheads in A and C show a regenerating fiber that is dMHC positive but luciferase negative. Similarly, the white arrow points to a patch of regenerating fibers that are luciferase negative. The area outlined by the dotted lines in panels (A) and (C) shows a cluster of late regenerating fibers that are both dMHC negative and luciferase negative. The micrograph in (D) shows a muscle lesion double-labeled with luciferase (green) and CD11b (red, a marker for immune cells). Double stained areas of panel (D) appear as yellow. All cross sections were counterstained with DAPI (blue) and were photographed at 20× magnification.