BM-SP cells engraft into skeletal muscle but have limited sarcoglycan expression. Normal male quadriceps (A_C) and female Sgcd^–/– recipient quadriceps muscle sections (D_F) were stained for γ-sarcoglycan immunoreactivity (A and D, red) and then subjected to FISH with a Y chromosome_specific probe, Y-1 (B and E, green). The merged images along with DAPI staining (blue) in C and F show nuclear localization of the Y-1 signals. Arrows in D_F indicate Y-1_positive cells engrafted between myofibers. The arrowheads in D_F show a Y-1_positive nucleus inside a myofiber. Despite engraftment, sarcoglycan expression was not restored. (G) A single γ-sarcoglycan_positive cell detected in δ-sarcoglycan_null quadriceps after transplantation with BM-SP cells. (H) A serial section of the same donor-derived cell also expresses δ-sarcoglycan. (I) Immunostaining of a transplant-recipient muscle with dystrophin and concomitant FISH with the Y-1 probe to detect donor nuclei (dystrophin, red; Y-1, green; DAPI, blue). Arrowheads in I indicate 3 Y chromosome signals in the central or peripheral nucleus position. Scale bars: 50 μm.