Effect of urea on endolymphatic hydrops in guinea pigs.

The morphological changes of the inner ear were observed after intravenous administration of 2 g/kg of urea to the guinea pigs with endolymphatic hydrops which had previously been produced by injecting 10% silver nitrate solution into the endolymphatic sac. They showed membranous collapse extensively in the saccule, moderately in the lower turns of the cochlea and less in the upper turns and the utricle. Because of these changes, it is reasonable to assume that urea is causing the endolymph to be reabsorbed in the endolymphatic duct. Furthermore, the effect of urea seemed to depend on the pathological condition of the duct which sometimes showed a varying degree of atrophied change after silver nitrate injection.