Fig. 6. AN-10i myoblast differentiation is impaired in regenerating skeletal muscle. (A) Representative photomicrographs of skeletal muscle transverse sections 7 days after grafting with C2C12i and AN-10i myoblasts. ß-Galactosidase was detected with X-Gal staining and skeletal muscle fibers were detected by immunohistochemistry against -dystroglycan. ß-Galactosidase-positive nuclei can be found incorporated into myofibers (C2C12i and AN-10i, upper panels) or in mononuclear cells in the interstitial tissue (C2C12i and AN-10i, lower panels). Scale bar: 25 µm. (B-D) Quantification of the ratio of ß-galactosidase-positive cells expressing differentiation markers (embryonic myosin or -dystroglycan) among total ß-galactosidase-positive cells in transplantation experiments shows that only a minority of the grafted cells from both groups had differentiated 3 days after transplantation, and that on the fifth and seventh day fewer AN-10i myoblasts were incorporated into myofibers than wild-type C2C12i myoblasts (^*, P<0.01, unpaired Student's t-test).