FIG. 1.

Clusters of human spectrin-positive myofibers are detected in mice injected with human cells. (A–I) Recipient NOD/Rag1^nullmdx5^cv muscles 45 days after injection of 1×10⁵ MCAM⁺ human fetal cells. (A–C) Coexpression of human spectrin and dystrophin (antibody recognizes both mouse and human proteins) documents human cell engraftment in myofibers. (D–F) Human spectrin-positive myofibers contain nuclei expressing human-specific lamin A/C. (G–I) Clusters of small myofibers reactive to human spectrin but negative for dystrophin expression. H-spectrin, human spectrin; h-lamin A/C, human lamin A/C. Scale bar: 50 μm