Malignant Clara cell line derived from ethylnitrosourea-induced murine lung adenomas

Lung adenoma induced in Swiss-Webster mice by transplacental exposure to ethylnitrosourea were minced, cultured and carried as cell lines for up to 2 years. The evolution of cell lines was followed every 3 months by ability to grow in nude mice and by morphological and ultrastructural examination of the tumors. Four cell lines, each originating from a single cell inoculum, were cloned. One of these produced mainly papillary tumors in nude mice and ultrastructurally had the morphology of Clara cells.