Immunohistochemical identification and localization of actin and fimbrin in vestibular hair cells in the normal guinea pig and in a strain of the waltzing guinea pig.

Using immunohistochemical methods, actin and fimbrin were identified and localized in vestibular epithelia iin the normal guinea pig and in the waltzing guinea pig. In the normal guinea pig, actin was found in the stereocilia and in the cuticular plate. Fimbrin was detected in the stereocilia but surprisingly not in the cuticular plate. As fimbrin was found in the cuticular plates in cochlear hair cells it is suggested that the hair cells in the two organs have different mechanoreceptor properties which can demand different cuticular plate stability. In the waltzing guinea pig, actin was found in the stereocilia, in the rod and n the cuticular plate. Fimbrin was seen in the stereocilia and in the rod, but could not be detected in the cuticular plate. These results emphasize the resemblance between the rod and the stereocilia. It is suggested that the rod is a genetically induced pathological intracellular type of stereocilium which grows in an uncontrolled manner.