Differences Between Stereocilia Numbers on Type I and Type II Vestibular Hair Cells

Moravec, W. J.; Peterson, E. H.

doi:10.1152/jn.00428.2004

Cited by 35 publications

(43 citation statements)

References 16 publications

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“…Next we divided this transect into bins (100 m wide, i.e., the width of the confocal image, and 25 m tall, i.e., along the mediolateral axis), and we counted the number of hair cells in each bin. Then we assigned each bin to a macular zone; we were able to determine zone boundaries by their distance from the line of hair cell polarity reversal (LPR; visible in this phalloidin-labeled material as changes in the orientation of the cuticular plate notch that marks the location of the kinocilium) and from changes in hair bundle arrays, because bundles in each zone have a characteristic array structure (Moravec and Peterson 2004;Rowe and Peterson 2006). In this way we were able to estimate hair cell density in each macular zone (see Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Zone 3 is a band of type I hair cells with their postsynaptic calyces and a small number of intercalated type II hair cells ; thus, in turtle utricle, type I hair cells and calyx-bearing afferents are restricted to Zone 3. The type I hair cells have significantly more stereocilia than all other macular hair cells (Moravec and Peterson 2004).…”

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“…First, the utricle is generally considered to be a dedicated vestibular organ (but see Zhu et al 2014); other otoconial organs such as the saccule and lagena may also function in hearing and seismic detection (Narins and Lewis 1984), which can complicate functional interpretations. Second, more is known about the structure (Moravec and Peterson 2004;Rowe and Peterson 2006;Severinsen et al 2003;Xue et al 2007;Peterson 2003, 2006), physiology (Meyer and Eatock 2011), and mechanical properties (Davis et al 2007; Davis and Grant 2014;Dunlap et al 2012;Dunlap and Grant 2014;Nam et al 2005Nam et al , 2006Nam et al , 2007aNam et al , 2007bSilber et al 2004; of hair bundles and the OM in turtle utricle than in any other species. These data have revealed four structurally and mechanically distinct macular zones (Fig.…”

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confidence: 99%

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Utricular afferents: morphology of peripheral terminals

Huwe

Logan

Williams

et al. 2015

Journal of Neurophysiology

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The utricle provides critical information about spatiotemporal properties of head movement. It comprises multiple subdivisions whose functional roles are poorly understood. We previously identified four subdivisions in turtle utricle, based on hair bundle structure and mechanics, otoconial membrane structure and hair bundle coupling, and immunoreactivity to calcium-binding proteins. Here we ask whether these macular subdivisions are innervated by distinctive populations of afferents to help us understand the role each subdivision plays in signaling head movements. We quantified the morphology of 173 afferents and identified six afferent classes, which differ in structure and macular locus. Calyceal and dimorphic afferents innervate one striolar band. Bouton afferents innervate a second striolar band; they have elongated terminals and the thickest processes and axons of all bouton units. Bouton afferents in lateral (LES) and medial (MES) extrastriolae have small-diameter axons but differ in collecting area, bouton number, and hair cell contacts (LES ϾϾ MES). A fourth, distinctive population of bouton afferents supplies the juxtastriola. These results, combined with our earlier findings on utricular hair cells and the otoconial membrane, suggest the hypotheses that MES and calyceal afferents encode head movement direction with high spatial resolution and that MES afferents are well suited to signal three-dimensional head orientation and striolar afferents to signal head movement onset. hair cells; turtle; utricle; vestibular afferents THE VESTIBULAR LABYRINTH is poorly understood compared, for example, to the auditory periphery and the retina. This is especially true of the major otoconial organs, the utricle and saccule, which encode linear head accelerations, including head position in gravity space, and transmit this information to the CNS. One important question is how the sensory surface of otoconial organs is organized to transduce the full range of signals generated by head movement. There are two broad possibilities: 1) all regions are equipotential in their ability to encode temporal properties of head movement (e.g., different frequencies, accelerations) or 2) different regions of the macula play distinctive functional roles.Considerable evidence supports the second of these alternatives. The best-known example of regional specializations in otoconial maculae is the ubiquitous division between striola and extrastriola: the striolar region of vertebrate maculae differs from the extrastriola in the structure and molecular composition of the otoconial membrane (OM) (e.g., Goodyear et al. 1994;Lim 1979;Lindeman 1969;Werner 1933; reviewed in Fermin et al. 1998;Lewis et al. 1985), which transmits the mechanical stimuli arising from head movements to receptors (hair cells), and in the structure and physiology of its hair cells (e.g

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Section: Discussionmentioning

confidence: 99%

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confidence: 90%

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confidence: 99%

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Utricular afferents: morphology of peripheral terminals

Huwe

Logan

Williams

et al. 2015

Journal of Neurophysiology

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“…First, our assignment of hair bundles to zones was approximate because we could not reliably visualize calyces in our DIC images to distinguish between type I and type II hair cells. Instead we identified zone boundaries by distance from the LPR, based on previous work (Moravec and Peterson 2004;Xue and Peterson 2006). This, together with the fact that such boundaries are naturally irregular, means that we may have made errors in assigning hair cells at the boundary between zones 2 and 3.…”

Section: Steady-state Stiffness Varies With Macular Locusmentioning

confidence: 99%

“…In this study, we took advantage of the orderly variation in hair bundle structure across the turtle macula (Fontilla and Peterson 2000;Jorgensen 1974Jorgensen , 1988Moravec and Peterson 2004;Rowe and Peterson 2006;Severinsen et al 2003;Xue and Peterson 2006) to examine covariation of bundle structure and stiffness. We had two goals.…”

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Steady-state stiffness of utricular hair cells depends on macular location and hair bundle structure

Spoon

Moravec

Rowe

et al. 2011

Journal of Neurophysiology

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Spoon C, Moravec WJ, Rowe MH, Grant JW, Peterson EH. Steady-state stiffness of utricular hair cells depends on macular location and hair bundle structure. J Neurophysiol 106: 2950-2963. First published September 14, 2011 doi:10.1152/jn.00469.2011.-Spatial and temporal properties of head movement are encoded by vestibular hair cells in the inner ear. One of the most striking features of these receptors is the orderly structural variation in their mechanoreceptive hair bundles, but the functional significance of this diversity is poorly understood. We tested the hypothesis that hair bundle structure is a significant contributor to hair bundle mechanics by comparing structure and steady-state stiffness of 73 hair bundles at varying locations on the utricular macula. Our first major finding is that stiffness of utricular hair bundles varies systematically with macular locus. Stiffness values are highest in the striola, near the line of hair bundle polarity reversal, and decline exponentially toward the medial extrastriola. Striolar bundles are significantly more stiff than those in medial (median: 8.9 N/m) and lateral (2.0 N/m) extrastriolae. Within the striola, bundle stiffness is greatest in zone 2 (106.4 N/m), a band of type II hair cells, and significantly less in zone 3 (30.6 N/m), which contains the only type I hair cells in the macula. Bathing bundles in media that break interciliary links produced changes in bundle stiffness with predictable time course and magnitude, suggesting that links were intact in our standard media and contributed normally to bundle stiffness during measurements. Our second major finding is that bundle structure is a significant predictor of steady-state stiffness: the heights of kinocilia and the tallest stereocilia are the most important determinants of bundle stiffness. Our results suggest 1) a functional interpretation of bundle height variability in vertebrate vestibular organs, 2) a role for the striola in detecting onset of head movement, and 3) the hypothesis that differences in bundle stiffness contribute to diversity in afferent response dynamics.

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Interspecific Variations of Inner Ear Structure in the Deep‐Sea Fish Family Melamphaidae

Deng

Wagner

Popper

2013

The Anatomical Record

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Inner ear structures are compared among three major genera of the deep-sea fish family Melamphaidae (bigscales and ridgeheads). Substantial interspecific variation is found in the saccular otoliths, including the presence of a unique otolithic "spur" in the genera Melamphaes and Poromitra. The variation in the saccular otolith is correlated with an increase in the number of hair bundle orientation groups on the sensory epithelia from the genera Scopelogadus to Poromitra to Melamphaes. The diverse structural variations found in the saccule may reflect the evolutionary history of these species. The sensory hair cell bundles in this family have the most variable shapes yet encountered in fish ears. In the saccule, most of the hair bundles are 15-20 lm high, an exceptional height for fish otolithic end organs. These bundles have large numbers of stereovilli, including some that reach the length of the kinocilium. In the utricle, the striolar region separates into two unusually shaped areas that have not been described in any other vertebrates. The brains in all species have a relatively small olfactory bulb and optic tectum, as well as an enlarged posterior cerebellar region that is likely to be involved in inner ear and lateral line (octavolateral) functions. Data from melamphaids support the hypothesis that specialized anatomical structures are found in the ears of some (if not most) deep-sea fishes, presumably enhancing their hearing sensitivity.

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Differences Between Stereocilia Numbers on Type I and Type II Vestibular Hair Cells

Cited by 35 publications

References 16 publications

Utricular afferents: morphology of peripheral terminals

Utricular afferents: morphology of peripheral terminals

Steady-state stiffness of utricular hair cells depends on macular location and hair bundle structure

Interspecific Variations of Inner Ear Structure in the Deep‐Sea Fish Family Melamphaidae

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