Physiological Change in the Endolymphatic Space During the Development of Endolymphatic Hydrops

The purpose of this experiment was to clarify the pattern of physiological change in the inner ear during the development of endolymphatic hydrops. Endolymphatic hydrops was experimentally induced in 67 guinea pigs by the introduction of silver nitrate into the endolymphatic sacs. The animals were sacrificed 1 day to 6 weeks later, and HE stained serial sections were made of their temporal bones. The endolymphatic spaces were examined under a light microscope and measured by computer to determine the pattern of size changes. The results were as follows :1) The saccule displayed the greatest degree of hydrops, with the saccules of the treated guinea pigs dilating to 7 times the size of the saccules in the control group.2) Cochlear hydrops developed principally in the upper turns during the first 3 weeks, and in the lower turns during the second 3 weeks. The final result was an even degree of dilation throughout the cochlea to a size 2.5 times normal.3) The utricle, which had been thought to display minimal dilatation, showed nearly the same degree of bulging as the cochlea : 2.5 times normal at 6 weeks.