Karyotypes of vasoformative sarcomas arising from BALB/3T3 cells attached to polycarbonate plates.

Four vasoformative sarcoma in vivo tumor lines arising from the s.c. implantation of 3 X 10(4) BALB/3T3 cells attached to a 1- X 5- X 10-mm polycarbonate platelet were shown to be quite similar in chromosome constitution to the parental 3T3 line. All tumors contained the same marker chromosomes that were present in the parent BALB/3T3 cells. The findings conclusively showed that the tumors had derived from BALB/3T3 cells and not from host cells or from the in vivo fusion of the inoculated 3T3 cells with host cells. Each tumor line had a unique karyotype that was markedly more homogeneous than that of the parental BALB/3T3 cells, strongly suggesting that each tumor represented a separate clone. An M1 marker chromosome was consistently present in each of the four tumor lines but was present in only about 50% of the parent BALB/3T3 cells; it therefore appeared to be a distinct and stable feature of the tumors.