The Transplantability and Growth of Urethan-induced Pulmonary Adenomas of the Mouse^*

Pulmonary adenomas induced with urethan in strain CAF₁ hybrid mice were excised after 1 year and sorted into four groups according to tumor diameter as follows: 0.5–1 mm., 1–2 mm., 2–3 mm. and >3 mm. Grafts approximately 1 mm. in size prepared from these tumors were transplanted subcutaneously into estrogen-treated and untreated mice and the animals sacrificed 4 months thereafter.

It was observed that hormonal treatment had no influence on incidence of takes, latent period, or subsequent growth of grafts regardless of the size of the primary tumor from which each graft was prepared. On the average, grafts from the larger primary tumors yielded a higher incidence of takes, required less time to become established, and grew to a larger size than did grafts derived from the smaller primary tumors. The possible limitations of technic and the relationship of these results to the development of primary lung tumors in situ have been discussed.

Tumor growth among the transplants appeared to have increased over that anticipated for the primary tumors in situ. Sarcomatous areas were observed among some of the grafts that grew to a relatively large size, but not among the primary tumors.