Human MM cells grow in fetal human bone implants within SCID-hu mice. SCID-hu mice were treated with irradiation (400 cGy), injected directly into the marrow cavity of the left fetal human bone implant with 5 × 10⁴ ARH-77 MM cells or with PBS, and killed 12 weeks later. H&E-stained tissue sections of the left human fetal bone marrow implant from SCID-hu mice injected with ARH-77 MM cells (original magnification × 100 [A]) or PBS (original magnification × 40 [B]) are shown.

Immunoperoxidase staining of the same human fetal bone marrow implant from SCID-hu mice injected with ARH-77 MM cells was also performed using antihuman κ (original magnification × 100 [C]) and antihuman λ (original magnification × 100 [D]) Ig light chain Abs.