Experimental osteosarcoma in the mouse, induced by Moloney's murine sarcoma virus.

The writers report an experimental trial on the mouse, consisting in the induction of osteosarcoma by inoculation of Moloney's murine sarcoma virus (MSV-M) into the proximal metaphysis of the tibia. This experiment was conducted on 90 BALB/c female mice aged twenty-one days and of mean weight 12.8 g. One group of animals was also given immunodepressive drugs. The tumour developed in 100 per cent of cases, producing metastases in some of the animals and resulting in death in three cases. The radiographic changes were initially osteolytic followed later by new bone formation. The histological examinations confirmed that the tumour was of an osteosarcomatous nature. Cells characteristic of rhabdomyosarcoma were observed in the soft tissues surrounding the bone. The skeletal metastases had the characteristics of osteosarcoma, while those in the lymph glands and lungs had those of an undifferentiated sarcoma. The writers also took into consideration a series of previous trial performed at the Institute of Clinical Orthopaedics of the University of Milan, involving a total of 740 mice, in arriving at their final conclusion that MSV-M induces, in the mouse, an osteosarcoma similar to spontaneous osteosarcoma in man, capable of producing osteoid tissue, of giving rise to metastases, and of causing the death of the animal.