Ultrastructure Damage To Inner Ear And Protection Of Steroid On Corti's Organ During Acute Experimental Otitis Media In Guinea Pigs

1.Ultrastructure of middle and inner ear in experimentally induced otitis media in guinea pigsThere are four kinds of cells in normal middle ear mucous, namely the ciliated cells, nongranular noncitiated cells, granular nonciliated cells and platycytes, and the distribution of the cells varied at different loci of the epithelium. The ciliates array to Eustachian tube. In the inflamed mucosa, the epithelium is thicker than the normal mucosa, and the epithelial cells are detached, mucus is produced by mucosa .Cells are disordered and look as if they going to be exfoliated, ciliated cells do not stand upright, cilia are disarrayed and splayed. The experimental animals are divided into two groups,the right middle ears are inoculated with Staphylococcus aureus and Pseudomonas aeruginosa respectively, with the left ears serving as controls. In inflammation,there may have effect on the inner ear,and the alterations of ultrastructure in the group of Pseudomonas aeruginosa are more apparent than the group of Staphylococcus aureus-infected.There are abundant of inflammatory cells observed in cochlea, and loss of outer hair cell cilia in the third row are observed. Oedema, vacuolation of mitochondrion, dilatation of endoplasmic reticulum,deposition of calcium salts and infiltration of inflammatory cells can be seen in the outer and inner hair cells. In stria vascularis,vacuolation of columnar epithelium,abolition of microvillus,vacuolation of mitochondrion, dilatation of endoplasmic reticulum ,gain of tight junctions and degeneration of endothelial cell vessels can be observed.Utricle and saccul hair cells degenerated, vacuolation of mitochondrion ,isolation of myelin sheath layers,axonal lesion and formation of corpuscular lamellose (Paccini's corpuscles) can be seen in vestibule hair cell and nerves. These morphology changes suggests in early acute otitis media middle ear mucosa and cochlear function might be disturbed. Damage to the organ of Corti after bacterial invasion of the inner ear may be one of the mechanism by which bacterial otitis media can cause hearing loss. Some gram-negative organisms which produce endotoxin may have more serious effect than gram-positive organisms on ultrastructure of middle and inner ear in experimentally induced otitis media in guinea pigs.It is very important to understand bacteriology of AOM and drug sensitivity of isolated bacteria for better early diagnosis and treatment of AOM .It helps to decrease taking place sensorineural hearing loss. 2.AIterations of middle ear mucosa nerve of the guinea pig with acute suppurative otitis mediaImmunohistochemical ABC method is undertaken to explore the changes in the neural distribution of the middle ear mucosa in experimental acute suppurative otitis media of guinea pigs. In the normal middle ear mucosa, the PGP9.5 positive fibers distributed as a net web and go along the longitude of the vessels. The presence of inflammation in middle ear induced congestion, oedema, haemorrhage, and the positive fibers of PGP9.5 decreased. It may be induced by degeneration of nerve fibers and increased release of nerve-tagged protein. The result indicates that the change of peptide possibly plays an important role in the mechanisms of otitis media and there may be some relations between the system nerve and immunity. 3.The effect of inflammation on inner ear microvessals permeabitity and itsrelationship with hearving threshld.Average ABR threshold is 10.000±4.472dB in normal guinea pig. Third days after infected i, the control ear average ABR thresholod is 10.833±3. 764, the infected ear average ABR threshold is 30.833±10. 206 dB .There are increased electric density of lanthanum ion which is found with linear distribution. In the surface of cochlea Corti's organ and vascular stia endotheliocyte of normal guinea pig under electron microscopic observation, no lanthanum ion seeps in intercellular space. Third days after infection, the tight junctions between micro-vessel endotheliocytes in basic membrane and vacular stria are distroyed and...