Chromosome Investigations of the Usubuchi Sarcoma

I. Studies in seven transfers from the 1812th to 1895th generations

Abstract

Chromosomes of the Usubuchi sarcoma cells are investigated in some detail, use being made of banding techniques, in seven samples from the 1812th to 1895th transfer generations. The sarcoma is regarded as a hypertriploid tumor in the generations examined, with a modal number of 65. This hypertriploid tumor scarcely comprizes in its chromosome complement disomic or trisomic homologues, as well as the normal rat chromosomes. The karyotypic constitution of the US cells is quite different numerically and morphologically from that of the normal rat karyotype. Seven chromosomes with unusual morphology are remarkable in occurrence as markers. In three of them (M5, M6 and M7), their possible derivation is traced on the basis of their characteristic banding patterns. The combination of the markers widely varies from cell to cell even in the sample from the same transfer generation. Their combination pattern seems to be irrelevant to either the number of chromosomes or the transfer generation.