Morphological Aspects and Functions of Endolymphatic Sac in the Guinea Pig

In 1965, Kimura and Schuknecht showed that blockade of endolymphatic sac and duct in the guinea pig produces on endolymphatic hydrops. Since this time, underabsorption of endolymph by the endolymphatic sac has been implicated as a cause of Meniere's disease.But analysis of inner ear fluids taken from experimental hydrops or Meniere's patients show no significant changes in ion activities or protein contents.From this results, it seemes to be necessary to research the functions of endolymphatic sac still more.In this paper, biochemical and physiological research were made about the fluids of the endolymphatic sac.K+ activity of endolymphatic sac fluid was 9 times lower than in the cochlear part of endolymph.After injection of Thorotrast in the endolymphatic sac, this particle could be found in the cochlear endolymph 2 days later. Ethacrynic acid injected into the peritoneal space (60mg/kg) shows a decrease of K+ activity in the cochlear endolymph but an increase in the endolymphatic sac. This effect was controlled by light and electron microscopic pictures.Pratein content in the endolymphatic sac was about 14 times higher than in the cochlear endolymph.But this differences of protein contents between endolymphatic sac and cochlear endolymph seemes to be difficult to induce the endolymphatic hydrops from the point of view of osmotic pressure.