Auditory canal structures in rats as altered by aging and by the administration of tris(p-aminophenyl)carbonium pamoate.

This study was concerned with changes in the auditory canal and its associated structures in rats as affected by aging and by oral administration of tià ̄s(p-aminophenyl)carbonium pamoate (TACP). Multiple sections of tissue blocks from the auditory canal area were reviewed in control and treated animals of both sexes, and of varying ages up to 18 months. Tumors were found in the auditory canal gland of both treated and control animals, but with greater incidence and shorter latent period in the treated animals. The incidence of tumor formation was higher in female than in male rats. Further, tumors were found in the sebaceous glands of the ear canal, but in the treated animals only. Cystic glandular changes related to aging appeared to contribute to tumor formation and development.