Auditory epithelial migration. IV. Light- and scanning electron-microscopic studies of the tympanic membrane and external auditory canal in the mouse.

The fine structures of the tympanic membrane and external auditory canal (EAC) were observed in the mouse under both the light microscope and scanning electron microscope. According to the differences in morphological features of the epidermis and epidermal cells, they were grossly classified into 8 types of region: (1) the region of the handle of the malleus, (2) the intermediate region of the pars tensa (PT), (3) the annular region of the PT, (4) the region of the pars flaccida, (5) the annular region of the anterior, inferior and posterior walls of the EAC, (6) the osseous region of the anterior, inferior and posterior walls of the EAC, (7) the region of the upper wall of the EAC and (8) the cartilaginous region of the anterior, inferior and posterior walls of the EAC. The specific structure "finger-like projections' was visualized throughout in the annular region of the EAC. The morphology of the region of the upper wall of the EAC was almost identical with that of the cartilaginous region of the anterior, inferior and posterior walls of the EAC.