Freeze-fracture studies on the perilymph-endolymph barrier in experimentally induced hydrops.

A double-blind study was performed on nine pigmented guinea pigs which were unilaterally operated on in order to create an endolymphatic hydrops. After 12-18 months, both inner ears of the animals were removed and investigated by the freeze-fracture technique. The ultrastructure of the epithelial cells lining the endolymphatic compartment of the cochlea and the vestibular apparatus was analyzed. Special attention was directed to possible changes of the tight junctions (zonulae occludentes) in these sites. The number and depth of strands between the cells of sensory and non-sensory epithelia of both operated and unoperated sides were compared by an examiner unaware of the operated side. After the code of double-blind study was broken, it was found that there were no significant differences between the operated and the unoperated ears. These results are discussed in relation to the late DC-potential decrease in experimentally induced hydrops.