Carcinogenic Effect of Egg Yolk in Mice of the C57 Bl Strain. ∗

Summary

Mice of the C57 Bl strain maintained on a diet supplemented with raw egg yolk, like those of the T.M. strain, developed a high incidence of neoplasms. The most frequent neoplasms were lung tumors and lymphosarcomas. Liver hepatoma, which occurred rarely in mice of the T.M. strain, was found in 6.5% of the experimental C57 Bl strain mice. The incidence of mammary cancer in these mice was only 9.6%, as compared with the 33% found among the breeding females of the T.M. mice on the diet supplemented with yolk; a difference which may probably be due to a difference in genetic constitution of these two strains of mice. Finally, many of the mice of the C57 Bl. strain on the diet supplemented with egg yolk developed pituitary tumors, the majority of which appeared to originate from the intermediate lobe.