1Karolinska Institute, Center for Hearing and Communication Research, Stockholm, Sweden/2Tokyo Medical University, Tokyo, Japan/3Karolinska University Hospital, ENT clinic, Stockholm, Sweden

■ OBJECTIVE: The German Waltzing guinea pig is a special strain of animals with a recessively inherited inner ear defect, resulting in deafness and a severe vestibular dysfunction. In the cochlear part the hearing loss is a result of a collapse of Reissner's membrane and absence of scala media.

■ METHODS: German Waltzing guinea pigs (homozygous and wild type) of different ages ranging from embryologic (E) age 50 days to adult animals were investigated. The living animals were tested with 6 different vestibular tests and the E animals were controlled according to breeding. Morphology of the vestibular parts (ampulla, saccule and utricle) were shown in the light and transmission electron

■ RESULTS: A collapse of the membranous labyrinth was found already at E50 with a progress over time. Vestibular dysfunction was noted already from birth.

■ CONCLUSIONS: Vestibular atelectasis, described 1998 by Merchant and Schuknecht is a vestibular disease in humans, that has been shown to have the same morphology as the reported vestibular dysfunction in the German Waltzing guinea pig. Due to this similarity this animal can be a good model for vestibular research. microscope.