Development of Tumor in Transplanted Lungs of Newborn and Adult Mice 1

Abstract

Discussion and Summary

After terminating the present series of experiments, we found in the literature that Heston had employed the analogous methodological approach in order to confirm the difference in degree of genetic susceptibility to tumor formation in susceptible strain A and resistant strain C57L lung and had shown that the genetic factor of the susceptibility to the development of pulmonary tumor in mice resides in the lung per se (5).

In order to explain the reason of higher susceptibility in the newborn animals to chemical carcinogenesis, Toth itemized the following alternatives: (1) detoxification and metabolism rates of carcinogenic chemicals are different in newborn and adult animals; (2) the rate of development and size of organs in newborn is greater than in adult animals; (3) involvement of a viral factor; (4) the effect of hormonal status modulated by the age of the animals; and (5) the possible interference of immunological processes (6).

In the present study an attempt was made to clarify the difference in susceptibility to tumor formation between lung transplants of newborn and adult mice. The fact that the lung transplant from the newborns possesses higher susceptibility to the tumorigenic action of methylcholanthrene than those from the adults leads to the conclusion that the age factor which influences the tumorigenic responses in lung to the administration of methylcholanthrene is located in the lung of the mouse itself.