Short-term effects of iontophoresis on the structure of the guinea pig tympanic membrane

Abstract

Guinea pig tympanic membrane was anesthetized iontophoretically. The animals were sacrificed between 2 h and 4 days after the anesthesia and the tympanic membrane was studied histologically by light microscopy and transmission electron microscopy. Edema in the sub-epidermal connective tissue layer and detachment of the basement membrane from the basal cell layer were observed 2 h after iontophoresis. Eight and 12 h later, the epidermal layer between the handle of the malleus and the bony annulus peeled and retracted towards the bony annulus, leaving only hornified outer epidermis on the fibrous layer. Four days after iontophoresis, the retracted margin of the epidermal layer became greatly thickened and evidence of hyperplasia and migration was observed. This study has demonstrated that iontophoresis of the tympanic membrane produces remarkable histological changes. However, no perforation was observed.

Key Words:

• ultrastructure
• tympanic membrane