Susceptibility of Mammary Tissues of Different Strains of Mice to Tumor Development

Summary

Mammary glands from mice of strains C3H, C3Hf, C57BL, GR, and GRz were transplanted into the mammectomized F₁ hybrids of these strains. In each hybrid one mammary gland of the highly susceptible strains C3Hf and C3H and one of the C57BL or the GR and GRz strains were compared with respect to tumor development. Both reciprocal hybrids were used. The results with the C57BL compared with the C3Hf were clear-cut: The mammary gland of the C57BL strain was more resistant to tumor development under identical conditions than the mammary gland of the C3Hf mouse. This was true in the presence and absence of the mammary tumor agent. The action of genetic factors determining the susceptibility to tumor development in the mammary gland is in the gland itself; no action of genetic factors through a general systemic mechanism could be demonstrated. Evaluation of the susceptibility of the GR and GRz strains as compared with that of the C3Hf and C3H was complicated by the presence and possible interplay between the two viruses in these two strains. Probably there is not much difference in the susceptibility of the mammary glands to tumor development in the C3H and C3Hf on the one hand and the GR and GRz strains on the other.