differential induction of squamous cell carcinomas , adenomas , and adenocarcinomas was observed in the lungs of male c57bl/6 and c3h/he mice after repeated intratracheal instillation of benzo ( a ) pyrene ( bp ) and charcoal powder suspended in 0.9 % nacl solution . when a high dose of bp ( 1.0 mg bp and 0.5 mg charcoal powder ) was instilled intratracheally once a week for 8 weeks or when a low dose of bp ( 0.5 mg bp and 0.5 mg charcoal powder ) was instilled once a week for 16 weeks , squamous cell carcinomas were induced in high incidence ( 77 to 87 % ) in the early period of observation , whereas pulmonary adenomas and adenocarcinomas were induced in low incidence ( 0. to 48 % ) in the late period of observation in both strains of mice .
C0024109
lungs
C0345964
pulmonary adenomas