On the Genetic Character of Neoplastic Cells as Determined in Transplantation Experiments

There are several studies concerned with the elucidation of the genetics of transplantability of neoplasms in mice (12, 33). The results have varied with the inbred stocks used, but one fundamental question is raised by all: Is the transplantation pattern of neoplastic cells different from that of normal cells ? The earliest investigations on transplantation of neoplastic and normal tissues were made with genetically heterogeneous animals and did not permit a clear-cut answer to this question. Strong (52) and Little and Strong were the first to study the fate of grafted tumors in closely inbred lines of mice that were genetically homogeneous. They found two adenocarcinomas of the mammary gland originating in their dBr stock, which could be transplanted within the line of origin and to first generation hybrids but failed to grow in another stock (Bagg albino). Bittner (4) found two tumors originating in F1 hybrids derived from Little's dBr stock and Bagg albino. These were transmissible to almost all F1 animals, but failed to grow in the parental stocks. In postulating a genetic basis for these findings, Bittner assumed that the simultaneous presence of 7 or 8 genes was required for transmission of tumors originating in the F1 hybrids. Similar observations were made by MacDowell and Richter with leukemias arising in their inbred stock C58. Kirschbaum and Strong (27) have confirmed the transplantation pattern found by Bittner with leukemias arising in hybrids of their inbred stocks F and CBA. They point out that their results are consistent with those found for transplantation of normal spleen by Bittner (6). Thus, Strong