Development of Dunn osteosarcoma inoculated into subcutaneous air pouch in mice

Dunn osteosarcoma cell growth was observed in C3H/Hej mouse subcutaneous air pouch. Inoculation with Dunn osteosarcoma cell suspension was performed by injection into air pouches of 70 mice on Day 7 after the initial injection of air. The developmental pattern of the tumor cell colonies was classified histologically into five stages. In Stage 0 (stage of no tumor cells), there were no tumor cells. In Stage 1 (focal stage), the colonies were limited to the lining-cell layers. In Stage 2, (segmental stage) the colonies protruded into the cavity of the pouch. In Stage 3 (annular stage), the total surface of the inner wall of the pouch was occupied by tumor cells. In Stage 4 (occlusive stage), the cavity of the pouch was fully occupied by tumor cells. The tumor was observed to develop to stage 1 in all mice 7 days after inoculation. The colonies were all found to be settled initially in the deeper layer of lining cells. Thus, the mouse air-pouch model is useful for direct observation of osteosarcoma cell growth.