Histological view of tibia of untreated and anti-α4 Ab-treated 5TGM1/luc-bearing mice. Note that the bone marrow cavity is occupied by 5TGM1/luc myeloma cells, and no trabecular bones are seen in the untreated group (A, C). On the other hand, normal marrow elements and trabecular bones are still observed in the anti-α4 Ab-treated group (B, D). Slides were examined using an Olympus BX-40F4 microscope equipped with a film camera (Olympus, Melville, NY). Panels A and B: lower magnification (H-E, × 40); panels C and D: higher magnification (H-E, × 200). Histomorphometric analysis of remaining trabecular bone/total area (E) and osteoclast number at the interface between myeloma and bone (F). Data are mean ± SEM (n = 5). ^*Significantly different from non-tumor-bearing (NTB) mice. ^**Significantly different from untreated 5TGM1/luc-bearing mice.