The round window membrane serves as the only soft tissue barrier separating the middle and inner ear. Its participation in the phase differential permitting the labyrinthine fluids to move under the influence of the stapes is better understoodi-P than its permeability characteristics in allowing certain chemical constituents to reach the inner ear fluids. 3 ,14 ,16 The purpose of this study is to report a description of submicroscopic morphologic details in animals (monkeys and guinea pigs). It is hoped that such information will be relevant to a better understanding of the physiologic and clinical implications of round window function. METHOD AND MATERIALThe temporal bones of adult male squirrel monkeys and guinea pigs were employed in these experiments. After the middle ear cavity was perfused with chilled 4% paraformaldehyde buffered with phosphate (pH 7.4) containing 1% sucrose, by means of injection through the tympanic membrane, the animals were decapitated and the temporal bones were opened. With the aid of an operating microscope, a small dental burr was used to make a hole between the round and oval windows. A second hole was made in the stapedial footplate. Through these holes the fixative was injected into the inner ear at low pressure. The temporal bones were then immersed in fresh fixative for two hours at 4 0 C, after which they were washed in cold phosphate buffered (pH 7.2) with added 1% sucrose. In the washing solution, the round window membrane was dissected free from the surrounding bone under the operating microscope. The specimens were postfixed in 1% osmium tetroxide buffered with phosphate (pH 7.4) for one hour at 4 0 C. They were then dehydrated with an ascending series of ethyl alcohol and embedded in Epon 812.Ultrathin sections were obtained with an LKB ultratome and Porter Blum microtome. The sections were double stained with uranyl acetate and lead acetate. Some sections were stained in 1% aqueous phosphotungstic acid for demonstration of elastic fibers. Micrographs were obtained using an RCA-EMU-3G electron microscope.OBSERVATIONS

No abstract

No abstract

No abstract