CARRAGEENINS-INDUCED OTITIS MEDIA IN ANIMAL

Otitis media was induced in guinea pigs and chinchillas by intrabullar injection of 1% carrageenins. The animals were sacrificed for histological examinations at 1 to 14 days respectively. In chinchillas tympanogram was performed by means of impedance audiometry. The gross appearance of bulla was most hyperemic, and thickened mucosa reaction were observed on the 3rd or 4th day. Effusion was also most abundant on the 3rd or 4th day, and tvmpanogram showed the lowest compliance and gradient in chinchillas. Each specimen was examined under light and electron microscopes. At 24 hours, the subepithelial layer was edematous, and epithelial cells contained electron dense granules. On the 3rd day, epithelial and subepithelial layers were most remarkably edematous, and macrophages, neutrophils and mast cells were seen in the mucosa. The macrophages contained many electron dense granules and dispersed lyso somes. Some of them were present adjacent to the capillaries, which permeability appeared to be enhanced. The mast cells granules showed less electron density and some of them fused with each other. In the 7th and 14th day specimens, the edema had disappeared and infiltrated cells were not numerous. According to the morphological findings, columnar metaplasia and goblet cells in this study were less frequent than in clinical otitis media with effusion. We suspect that the mucociliary clearance system of the Eustachian tube almost maintains it normal condition. At least carragerenins induced otitis media did not effect tubal mucociliary transport.