EXPERIMENTAL OBLITERATION OF THE ENDOLYMPHATIC SAC AND THE PERILMPHATIC DUCT

1. The endolymphatic sac was destroyed and obliterated by an extradural approach in 31 ears of guinea-pigs. A complete obliteration was confirmed by the histological examination in nine of them, which were 24 hours to 53 days postoperative. Endolymphatic hydrops developed as early as 24 hours after the operation and was slowly progressive thereafter, causing flattening or compression of the organ of Corti in two postoperative weeks. The hydrops was interpreted as a “retention hydrops” due to the interrupted resorption of endolymph. Thus, in contrast to the inconsistent results of the former works concerned, the present experiment clearly demonstrated the inevitability of the endolymphatic sac as a resorptive organ of endolymph.2. Sodium and potassium concentration of endolymph and perilymph was measured by using atomic absorption spectrophotometer in 73 ears of guinea-pigs, which were 24 hours to one month postoperative of the obliteration operation of the endolymphatic sac.In comparison with the non-obliterated ears, potassium increased in endolymph and vestibular perilymph but decreased in scala tympani perilymph, while sodium decreased in vestibular perilymph but not significantly changed in endolymph and scala tympani perilymph. It was clarified by the experiment that the “retention hydrops” was an entity associated with the electrolyte (Na, K) changes in the inner ear fluid.3. An obliteration operation of the perilymphatic duct was performed in 26 ears of guinea-pigs by an intradural approach. A complete obliteration was histologically confirmed in only four ears of them, which were 48 hours to 13 days postoperative. The findings characterized by the buldging of Reissner's membrane and the nubecular precipitate in the perilymphatic space without compression of the organ of Corti, were interpreted in terms of the “ passive endolymphatic hydrops ” due to the interrupted supply of perilymph. A conclusion was drawn that the perilymphatic duct was an important supply route of perilymph from the subarachnoid space.