Uptake of radioactive sulphur in the endolymphatic sac. An autoradiographic study

Autoradiographic uptake of labelled sulphur (S35) in the endolymphatic sac was analysed after performing surgical labyrinthectomy and after systemic administration of glycerol and ethacrynic acid. Accumulation of radioactive substance was observed after surgical labyrinthectomy and associated with a deposition of stainable substance in the endolymphatic sac lumen. Increased activity was noted in the epithelial layer after administration of ethacrynic acid, whereas glycerol did not increase radioactivity in the endolymphatic sac despite the deposition of stainable substance therein. This fact was believed to depend on a too short time interval between the injection and the sacrifice of the animals, as well as a weaker concentration of the sulphated compound within the endolymphatic sac. The results suggest that the endolymphatic sac may secrete sulphur-containing substances presumably associated with a deposition of a stainable substance in the endolymphatic sac.