Variation in cell surface morphology of two 90Sr-induced osteosarcomas serially transplanted in CBA mice.

The induction of skeletal tumours, which can be classified as osteosarcomas of many different types, is considered to be the primary carcinogenic effect of radiostrontium. In the present report the cell surface morphology in vivo of 90Sr-induced osteosarcoma cells was investigated, since a variety of tumour cells--and especially those investigated in vitro--have been shown to possess morphologic changes compared with their normal counterparts. Using scanning electron microscopy, variations in cell surface morphology were observed in 2 tumour series, which were serially transplanted in mice for 45 and 60 transfer generations, respectively. The slow-growing osteosarcoma cells of the early transfer generations, of osteoblastic as well as fibroblastic type, seemed to have more cytopodia than the fast-growing osteosarcoma cells from later generations. This may be due to the fact that slowly growing cell populations have a large proportion of cells in G1, in which stage there is a higher frequency of cellular cytopodia.