A method for rapid scoring of respiratory tumors in hamsters

The larynx, trachea, and lung of Syrian golden hamsters treated with diethylnitrosamine were stained with modified Wright's stain and rendered semitransparent by a clearing technique. Areas of dense cell aggregation (tumors) were readily observable under a dissecting microscope. Tumor scoring at this subgross level correlated with subsequent microscopic evaluation, except that several tumors were found on the subgross level which would not have been observed during routine histologic procedures. The clearing method was used successfully to discern differences in tumor incidence in a dose-response study with diethylnitrosamine.