Induction of Squamous Cell Carcinoma in the Respiratory Tract of Mice 1,2

SUMMARY-Squamous cell carcinomas of the respiratory tract were induced in (C57BL X C3H)F1 (BC3Fl) and DBA/2 mice by repeated intra-tracheal injections of 3-methylcholanthrene (MCA). The tumors showed frank invasion and metastasis and were readily transplantable to isogenic recipients. In BC3F1 mice given 6 weekly injections of 0.5 mg MCA, a tumor incidence of 86 % with an induction time of 10-28 weeks was observed. Only 3 of 50 DBA/2 mice have developed squamous cell carcinomas at 7 months, after 4 weekly injections of 0.5 mg MCA. The exact origin of the observed respiratory tract carcinomas still needs to be determined.-J Nat Cancer Institute 47: 697-701,1971. IN respiratory carcinogenesis studies, rats and hamsters have largely replaced mice as experi-mental animals, because previously the so-called pulmonary adenoma was the only tumor readily inducible in the mouse respiratory tract (1, 2). Thi