Evaluating the rat inner ear. A technique using scanning electron microscopy.

The laboratory rat is the most commonly used species in safety evaluation of pharmaceutical compounds. However, surface preparations of the organ of Corti (OC) are difficult to perform in this species largely due to problems in removing the thick, bony otic capsule. A modified technique was developed using rapid decalcification to solve this problem. In addition, scanning electron microscopy was used to quantitate hair cell damage and/or loss after exposure of the OC by microdissection. It was found that hair cell loss and amage could be easily detected and quantified in rats given gentamicin sulfate.