Chromosomal analysis of primary and metastatic Rous sarcomas in the rat

The chromosomes of 13 primary and 4 secondary Rous sarcomas (RSV–SR) in the rat have been studied in fixations directly from the tumour. The general character of the chromosomal spectrum in the primary sarcomas was similar to that of the Rous sarcomas in the mouse and the Chinese hamster. However, normal diploid stemlines were considerably more frequent in the rat sarcomas; among the heteroploid stemlines it was noticeable that polyploids were absent and that pseudodiploidy seemed to be a more important evolutionary pathway than in the mouse and the Chinese hamster. Trends towards a non-random chromosomal engagement were noticed, both in the primary sarcomas and in the metastases derived from them.