Growth and cytogenetic characteristics of nickel sulphide-induced rhabdomyosarcomas in rats.

Rhabdomyosarcomas induced by single intramuscular injections of nickel sulphide (Ni3S2) in Fischer and Hooded rats were cultured in vivo and in vitro to study their growth characteristics and chromosomal constitution. The tumor cell suspensions cultured in vitro exhibited more myogenic differentiation on the coverslips than those cells grown in vivo in diffusion chambers. A characteristic feature of in vivo cultures was the appearance of microclusters which resembled the primary tumors. Chromosome analyses of primary tumors revealed that a majority of these had a modal number in the diploid or near diploid range. Fischer rat primary tumor cells exhibited abnormal configurations including rings, dicentrics and triradials. A comparison of the chromosome make-up of the primary tumors and their metastases was performed on four sets of tumors. Three out of four metastases examined showed the diploid chromosome make-up characteristic of the primary tumors suggesting that the tumors with the diploid or near diploid chromosome constitution are more likely to produce metastases.