Cytoskeletal Organization of the Human Inner Ear: II. Characterization of Intermediate Filaments in the Cochlea

Abstract

The distribution of intermediate filament proteins in the cochleae of eight human fetuses, 14–18 gestation weeks old, was investigated at the light microscope level using monoclonal antibodies (mAbs) against vimentin, cytokeratins (CK) (three different mAbs were used: PKK-1 detecting CKs 8, 18 and 19; PKK-2 detecting CKs 7, 17 and 19; and PKK-3 detecting CK 18), neurofilament proteins, glial fibrillary acid (OFA) protein and desmin. Vimentin positivity was found in the outer hair cells but not in the inner hair cells. Considerable variations in immunoreactivity for the different groups of cytokeratins was found in the epithelium lining the endolymphatic space. Two types of spiral ganglion cell bodies were characterized: those with intense immunostaining for neurofilament proteins (a minor cell population) and those lacking staining. GFA and desmin were not identified. Our characterization of intermediate filament proteins in the human embryonic inner ear permits a further microchemical characterization of cells and tissues at the light microscopic level. In addition, we have shown that also the same type of cells in the inner ear have a more complex cytoskeleton than visualized with routine light microscopy or with transmission and scanning electron microscopy.

Key Words:

• human
• labyrinth
• cochlea
• embryonic
• cytoskeleton
• intermediate filaments