Abstract
The frequency of polyploid tumor cells invading the lung of mice bearing Ehrlich hyperdiploid tumor (ELD) was reinvestigated by the organ graft technique. Pieces of lung tissue from mice bearing ascites tumors (containing 13 percent polyploid cells) were injected into the peritoneal cavities. The ascites tumors thus developed had 73.4 percent polyploid cells, while the control ascites tumors had only 11 percent. The experiment was repeated with another Ehlich tumor strain contatning only 2 percent polyploid cells. Ascites tumors, developing in two mice after lung tissue transplants, contained 26.7 and 28.1 percent, respectively, though control ascites tumors had 2.5 percent. To explain this phenomenon, two experiments were carried out: 1) ELD tumors containing only 0.2 percent polyploid cells were inoculated into the tail veins. Three metastatic tumors thus developed had 61.9, 40.4 and 17.9 percent polyploid cells, respectively, while the control animals had only 0.4 percent. 2) About 100 ELD tumor cells were injected directly into the brain, liver and under the skin to ascertain the difference, if any, in the occurrence of polyploid cells. No increase of such cells was observed in tumors developing after direct inoculation. From these experiments, cause of the increase of frequency of polyploid cells in metastatic tumors was discussed.
