Ultrastructure of nitrosoheptamethyleneimine-induced lung tumors in European hamsters.

The ultrastructure of lung tumors induced in European hamsters through chronic subcutaneous treatment with nitrosoheptamethyleneimine (NHMI) is described. The neoplasms demonstrated either adenomatous (adenomas and adenocarcinomas) or mixed (tumors with areas of adenoid and squamous differentiation) pattern. Adenomatous areas consisted of Clara cells and of cells with lamellated inclusion bodies in their cytoplasm. Cells in areas with squamous differentiation contained cytoplasmic filaments and filament bundles as well as dense-cored granules.