Cochlear Morphology in a Strain of the Waltzing Guinea Pig

Abstract

The morphology of the cochlear degenerative process was studied in a strain of the waltzing guinea pig with a dominant mode of inheritance. Already at birth, pathological features were found consisting of sensory hair coalescence and cuticular protrusions at the periphery of the hair-cell top. With increasing age the hair cells vacuolized, the plasma membranes ruptured and the cytoplasmic debris was dispelled into the endolymphatic space. The degenerative process started in the third row of the outer hair cells and on the inner hair cells. Spread occurred from a locus of predilection at the first and second turns; centripetally to involve all rows of hair cells; longitudinally to comprise all but the extremes of the organ of Corti. The supporting cells degenerated later than and in accordance with the neuroepithe-lium; finally the spiral ganglion showed depopulation of neurons. Other cochlear structures were morphologically normal. It may be that this endogenous sensory cell degeneration is caused by an intracel-lular “error of metabolism”, initiated by a defect in the genetic constitution.