Abstract
Newborn C57BL mice were injected subcutaneously with a single dose of 100 μg of 7,12-dimethylbenz[a]anthracene. A high neonatal mortality occurred, reducing to 23 percent the number of animals surviving at weaning time. Tumors were observed in 60.5 percent of the surviving 38 animals: 4 malignant lymphomas, 6 subcutaneous tumors at the site of injection, 5 skin tumors, 7 liver hemangiomas, 2 myocardial hemangiomas, 1 liver hemangiosarcoma, 3 multiple lung adenomas, 1 cholangioma. Among 102 untreated controls, there were 4 malignant lymphomas, 1 multiple lung adenoma, and 1 hepatoma. The average latent period, calculated at time of death, was of 30 weeks for the 4 lymphomas of the DMBA-treated group, and of 93 weeks for the 4 lymphomas occurring in the control group. These results indicate that DMBA given at birth, has a lower carcinogenic activity in C57BL mice than in other strains.
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