Chromosome counts of 90Sr-induced osteosarcomas in mice. II. Variation of the chromosome counts of slow and fast growing tumours in hyper- and nonhyperimmunized hosts

Chromosome counts of 90Sr-induced osteosarcomas in mice. III. Variation of the chromosome counts of in vivo transplanted tumours, in vitro cultures and retransplanted cultured cells

This investigation started from serially in vivo transplanted tumours. The chromosome patterns of in vitro cultures and of parallelly and serially transplanted tumours were examined. Cultured cells were also used for retransplantation to mice. When comparing the chromosome counts of the cultured cells and the in vivo transplanted tumours, significant differences were revealed. When retransplanting cultured cells, it was also noticed that a similar chromosome distribution appeared, as previously found in 90Sr-induced transplanted series.

Chromosome counts of 90Sr-induced osteosarcomas in mice. IV. Variation of chromosome counts when using tumours of predetermined age for transplantation

Transplanted tumours from a 90Sr-induced primary tumour were used as an experimental model to eliminate any connection between the chromosome distribution and outgrowth period of radiation-induced transplanted tumours. For this reason repeated transplantations were performed from different tumours of predetermined age from a transfer generation, to receive separate but parallel transfer generations. From each one of these generations a tumour of the same age as used to establish a particular generation was used for continued transplantation. It was then observed that the percentage of 40-chromosome cells in general decreased with the age of the tumour used for transplantation. Furthermore, early established transfer generations were often characterized by more slow growing tumours. However, it should be realized that even if a true relationship between chromosome pattern and outgrowth period cannot be eliminated, the differences found may be due to accidental variations.