GENETICS OF NEOPLASIA 



259 



Fig. 37. Outline of experiment localizing the action of genes controlling 



OCCURRENCE OF PULMONARY TUMORS IN THE END ORGAN. 



STRAIN L 

 (Resistant) 



A 



I 



LAF, 



STRAIN A 

 (Susceptible) 



L LUNG 

 TRANSPLANT 



A LUNG 

 TRANSPLANT 



INJECTED 1:2:5 = 6 -DIBENZANTHRACENE I. V. 



(Reprinted by permission from the Journal of the National Cancer Institute.) 567 



subcutaneously into one axilla of (A x C57L)F 1 hybrids and portions of lung from 

 C57L mice were transplanted into the other axilla. To shorten the experiment, the F 1 

 hosts were injected intravenously with dibenz[a, A] anthracene after the transplants had 

 been given two weeks to establish circulation. It could be expected that, if the action 

 of the genes were limited to the lung, many tumors would arise in the A transplants 

 and few in the G57L transplants, whereas if the action were manifest through some 

 other systemic mechanism the transplants would lose their susceptibility and resistance 

 identity, and both would develop tumors comparable with the lung of the F x host. 

 When the transplants were removed and sectioned four months after the hosts were 

 injected with the carcinogen, many tumors were found in the A transplants and very 

 few in the C57L transplants. Thus, the actions of the genes controlling occurrence of 

 pulmonary tumors by which these strains differed were being manifest in the end organ. 

 Shapiro and Kirschbaum 1193 used a variation of this technique in placing the 

 transplants of pulmonary tissue in the ear of the host where they could be observed 

 more directly. We 569 have used transplants of fetal lung to ascertain that the genetic 



