TRITIATED-THYMIDINE AS A BROAD-SPECTRUM INITIATOR IN TRANSPLACENTAL 2-STAGE CARCINOGENESIS, WITH PHORBOL AS PROMOTER

A single subcutaneous injection of 200 μCi [3H] thymidine into pregnant BALB/c mice, followed by intraperitoneal injections of phorbol, twice weekly for 25 weeks, in the offspring, resulted in higher tumour development in the lungs and livers of male and, to a lesser extent, of female offspring, than in their untreated littermates. The difference in over‐all tumour incidence was statistically significant, but the increases of the individual tumour types were only of borderline significance. Slight carcinogenic activity of [3H]thymidine alone was observed in the mothers, and in the offspring, without phorbol treatment. The results suggest the possibility of using [3H]thymidine as a broad spectrum initiator for transplacental two‐stage carcinogenicity studies to determine the organ specificity of different promoting agents. Copyright © 1979 Wiley‐Liss, Inc., A Wiley Company