Pathohistological study on active endolymphatic hydrops in guinea pig--with stress stimulations

Recently Meniere's disease is believed to show a pathological features of endolymphatic hydrops, but the etiology of this disease has not yet been ascertained. Many investigators tried to create animal models with endolymphatic hydrops by obliterating endolymphatic sac and duct. However, these methods have not been adequate to explain the mechanism of development of Meniere's disease, because it gives mechanical damage to destroy endolymphatic sac and duct. On the other hand, Meniere's disease is thought to develop even as a result of stress. The present paper reported the conduction of an acute experiment, creating active endolymphatic hydrops by stress load, to study the occurrence rate of endolymphatic hydrops and the pathological findings of inner ears by a light microscope. This was followed by a light and electron microscopic study on the changes in permeability of the cochlear lateral wall with horseradish peroxidase and a study of the development mechanism of endolymphatic hydrops. Results obtained were as follows: 1. Although it was impossible to cause endolymphatic hydrops with a single stimulation, four kinds of stress stimulations could cause endolymphatic hydrops with the rate of 37.8%. 2. Judging from the different pathological findings between the group with four kinds of stress stimulations and the untreated control group, vessel permeability in the stria vascularis was highly changeable, while that in the spiral ligament was not. 3. It was found out that increased permeability of the stria vascularis vessels was by increased pinocytotic vesicular transport and through tight junctions from vessel lumen to basal lamina and that it was presumably only by increased pinocytotic vesicular transport beyond basal lamina. 4. It was assumed that increased permeability of the stria vascularis vessels was one of the causes of endolymphatic hydrops which were believed to be pathological features of Meniere's disease.