Ultrastructural and physiological defects in the cochlea of the Mpv17 mouse strain - A comparison between young and old adult animals

Ultrastructural investigations were performed in young (approximately 2 mon ths) and old (7 months) Mpv17-negative and wildtype mice. The onset, the se verity and the pattern of the degeneration significantly differed between b oth mice strains. In the wild type mouse strain the degenerative changes of the cochlear structures were similar to the aging pattern described for ot her species. In contrast, the Mpv17 mutants showed degenerative changes of the cochlear structures already at the age of 2 months. The degenerative ch anges were patchy arranged throughout the entire length of the cochlea and involved the organ of Corti as well as the stria vascularis epithelia with alterations of the basement membrane of the capillaries. The severe sensori neural hearing loss and degenerative changes of the cochlear structures ind icate that cochlear structures, especially the outer hair cells and the int ermediate cells of the stria vascularis, are vulnerable to the missing Mpv1 7 gene product. (C) 2001 Elsevier Science B.V. All rights reserved.