Localization of specific lesions in dimethylbenz(a)anthracene-preexposed tracheal explants

An experimental model is described for separating out and identifying, by a nondestructive method, lesions induced in rat tracheal implants exposed to 200 micrograms dimethylbenz(a)anthracene (DMBA)-beeswax pellets. The approach was to cut exposed and nonexposed tracheas into 2 x 3-mm explants and place them in organ culture for 24 hours. The medium was collected, and the exfoliated cells in the medium were stained by the Papanicolaou method for cytologic diagnosis. The exfoliated cells were graded according to the degree of atypia by conventional cytologic criteria. To validate the cytologic diagnoses, 60 organ cultures were fixed, sectioned, and stained; and the histopathologic diagnoses were compared. In most cases, the cytologic findings were predictive of the histopathologic results. To test for alterations in growth characteristics of cell populations derived from specific lesions, epithelial cell cultures were established from 35 organ cultures. All primary cultures from explants showing moderate or more severe atypia, and 40% from those showing regular metaplasia or mildly atypical lesions, survived and grew in culture. Cultures from unexposed tracheas did not survive.