Auditory epithelial migration: I. Macroscopic evidence of migration and pathways in rat.

Auditory epithelial migration (AEM) was studied in the rat for up to 42 days following the application of dye on the tympanic membrane (TM) and external auditory canal (EAC). Migratory pathways were similar to those in the human. In the pars tensa (PT), pathways were radially and centrifugally oriented from the handle of the malleus (HM) toward the annulus. However, the pathway along the HM from the umbo to the pars flaccida (PF), as reported in the human, was not observed in the rat; instead, a shallow downward pathway along the HM. In the PF, the radial spread of dye-markings from the proximal part of the HM to the upper wall of the EAC, as found in the human, was also observed in the rat. We conclude that the TM and EAC of the rat constitute an appropriate experimental model with which to study the human type of AEM.