H & E stained sections of lumbar vertebrae from control and 5TGM1 myeloma-bearing mice treated with PBS or ibandronate (4 μg per mouse per day for 28 days). (A) Non–tumor-bearing control treated with PBS, (B) non–tumor-bearing control treated with ibandronate, (C) 5TGM1 myeloma-bearing mouse treated with PBS, (D) 5TGM1 myeloma-bearing mouse treated with ibandronate. The spinal cord (SP) is indicated in each figure. Note that in the non–tumor-bearing animals, (A) and (B), the marrow cavity is filled with normal marrow (BM). In contrast in myeloma-bearing animals (C) and (D), the normal bone marrow has been replaced by myeloma cells (MY), which have also invaded the surrounding tissues. In the myeloma-bearing animal treated with PBS (C), there is a clear loss of trabecular bone and also some loss of cortical bone. This bone loss is prevented by ibandronate treatment (D). Bar = 200 μm.