The Cytocaud: A Hair Cell Pathology in the Waltzing Guinea Pig

Abstract

The waltzing guinea pig displays severe inner ear dysfunction that involves both an auditory and a vestibular manifestation. The aim of this study was to characterize a pathological tail-like extension of the vestibular hair cells, the cytocaud. Our data suggest that nearly all type I hair cells in the waltzing guinea pig have cytocauds, which appear as membrane-bound tails containing mitochondria and cytoplasm that proceed in a basal direction toward the basement membrane. The extensions either attach to the basement membrane or penetrate it, and further proceed into the extracellular matrix. A core made of a thick and long (30 µm) actin-rich structure supports the slender long process. The actin core has cross-links that are periodically placed along the length of the cytocaud. Our data suggest that the cytocauds in vestibular hair cells of the waltzing guinea pig are highly organized structures associated with a failure to detach from the basement membrane.

Characterization of Two Transgene Insertional Mutations at Pirouette, a Mouse Deafness Locus

“…Similar actin-rich elements have also been observed in vestibular hair cells of the 'waltzing' guinea pig [Ernstson et al, 1969;Flock et al, 1979;Kanzaki et al, 2002]. Myosin decoration studies indicated that the actin filaments in cytocauds of shaker 2 mice and the waltzing guinea pig are oriented with their barbed (plus) ends directed to the base of the hair cell, consistent with growth in this direction [Flock et al, 1979;Sobin et al, 1982].…”

Type I hair cell degeneration in the utricular macula of the waltzing guinea pig

“…Although horizontal rotation-evoked nystagmus does not reflect the utricular function specifically, it is an effective way of identifying the affected animals (Canlon and Dulon, 1993;Kanzaki et al, 2002). Normal animals (controls) did not display any of these characteristics.…”

“…The filament rods were first described by Ernstson et al (1969) who named them ''rod-shaped inclusion bodies". They have since been called ''needles" by Flock et al (1979) and ''cytocauds'' by Kanzaki et al (2002). The rods consist of fimbrin and actin (Flock et al, 1979;Flock, 1981, 1983) and in some cases reach a length of 30 lm (Kanzaki et al, 2002).…”

Distinct capacity for differentiation to inner ear cell types by progenitor cells of the cochlea and vestibular organs

“…2C,H, arrowheads). Some of the phalloidin-positive structures resemble actincontaining 'cytocauds', a malformation of stereocilia that has been described in animals with inner ear mutations affecting hair bundles (Kanzaki et al, 2002).…”