Structure and Growth of the Utricular Macula in the Inner Ear of the Slider Turtle Trachemys scripta

Severinsen, Stig Åvall; Jørgensen, J. Mørup; Nyengaard, Jens Randel

doi:10.1007/s10162-002-3050-6

Cited by 19 publications

(19 citation statements)

References 51 publications

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“…11; Table 7); this trend is interrupted by a slight density decrease in the calyx band (Zone 3; Fig. 11) as reported in turtle (Rowe and Peterson 2006;Severinsen et al 2003) and rodent (Desai et al 2005) utricle. Collecting areas also decrease from lateral to medial (Table 7).…”

Section: Hair Cell-to-afferent Convergence Varies With Macular Locussupporting

confidence: 61%

“…C units in turtle contact one to five hair cells (median: 3) in our material. Severinsen et al (2003) report that turtle utricular calyces can contact up to eight hair cells but that two to four is most common. Finally, calyx clusters on C units are significantly more complex than those on D units in pigeon (Table 2 in Si et al 2003) and turtle (present results, Fig.…”

Section: Relation To Previous Work On Utricular Afferentsmentioning

confidence: 99%

“…It is clear that the MES and the LES are not simple mirror images of each other, differing only in hair cell polarity. In turtle hair bundles in both regions have large KS ratios, suggesting that both will have wide operating ranges (see discussion in ), but other bundle features and hair cell density differ in the two regions (Rowe and Peterson 2006;Severinsen et al 2003;Xue and Peterson 2006; present results; also in mice: Li et al 2008), as does afferent morphology (present results; also in bullfrog: Baird and Schuff 1994), and in the structure of the OM and the coupling between hair bundles and the OM (Davis et al 2007;Xue et al 2007;Xue and Peterson 2003). The functional role of the LES is unclear, but several lines of evidence suggest that turtle MES may be well suited to providing an ongoing readout of head orientation in gravity space.…”

Section: Organization Of the Maculamentioning

confidence: 99%

“…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.…”

mentioning

confidence: 99%

“…Zone 1 corresponds to the LES, and Zone 4 corresponds to the MES. These two extrastriolar zones have similarly compliant hair bundles ), but they differ significantly in the structure of their hair bundles (Rowe and Peterson 2006;Severinsen et al 2003;Xue and Peterson 2006) and overlying OMs (Davis et al 2007;Xue et al 2007;Xue and Peterson 2003). The remaining two zones constitute the striola.…”

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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: Hair Cell-to-afferent Convergence Varies With Macular Locussupporting

confidence: 61%

Section: Relation To Previous Work On Utricular Afferentsmentioning

confidence: 99%

Section: Organization Of the Maculamentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

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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Specializations of intercellular junctions are associated with the presence and absence of hair cell regeneration in ears from six vertebrate classes

Burns

Collado

Oliver

et al. 2013

J of Comparative Neurology

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Sensory hair cell losses lead to hearing and balance deficits that are permanent for mammals, but temporary for nonmammals because supporting cells in their ears give rise to replacement hair cells. In mice and humans, vestibular supporting cells grow exceptionally large circumferential F-actin belts and their junctions express E-cadherin in patterns that strongly correlate with postnatal declines in regeneration capacity. In contrast, chicken supporting cells retain thin F-actin belts throughout life and express little E-cadherin. To determine whether the junctions in chicken ears might be representative of other ears that also regenerate hair cells, we investigated inner ears from dogfish sharks, zebrafish, bullfrogs, Xenopus, turtles, and the lizard, Anolis. As in chickens, the supporting cells in adult zebrafish, Xenopus, and turtle ears retained thin circumferential F-actin belts and expressed little E-cadherin. Supporting cells in adult sharks and bullfrogs also retained thin belts, but were not tested for E-cadherin. Supporting cells in adult Anolis exhibited wide, but porous webs of F-actin and strong E-cadherin expression. Anolis supporting cells also showed some cell cycle reentry when cultured. The results reveal that the association between thin F-actin belts and low E-cadherin is shared by supporting cells in anamniotes, turtles, and birds, which all can regenerate hair cells. Divergent junctional specializations in supporting cells appear to have arisen independently in Anolis and mammals. The presence of webs of F-actin at the junctions in Anolis appears compatible with supporting cell proliferation, but the solid reinforcement of the F-actin belts in mammals is associated with its absence.

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Morphology of the utricular otolith organ in the toadfish, Opsanus tau

Boyle

Ehsanian

Mofrad

et al. 2018

J of Comparative Neurology

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The utricle provides the vestibular reflex pathways with the sensory codes of inertial acceleration of self-motion and head orientation with respect to gravity to control balance and equilibrium. Here we present an anatomical description of this structure in the adult oyster toadfish and establish a morphological basis for interpretation of subsequent functional studies. Light, scanning, and transmission electron microscopy techniques were applied to visualize the sensory epithelium at varying levels of detail, its neural innervation and its synaptic organization. Scanning electron microscopy was used to visualize otolith mass and morphological polarization patterns of hair cells. Afferent nerve fibers were visualized following labeling with biocytin, and light microscope images were used to make three-dimensional (3-D) reconstructions of individual labeled afferents to identify dendritic morphology with respect to epithelial location. Transmission electron micrographs were compiled to create a serial 3-D reconstruction of a labeled afferent over a segment of its dendritic field and to examine the cell-afferent synaptic contacts. Major observations are: a well-defined striola, medial and lateral extra-striolar regions with a zonal organization of hair bundles; prominent lacinia projecting laterally; dependence of hair cell density on macular location; narrow afferent dendritic fields that follow the hair bundle polarization; synaptic specializations issued by afferents are typically directed towards a limited number of 7-13 hair cells, but larger dendritic fields in the medial extra-striola can be associated with > 20 hair cells also; and hair cell synaptic bodies can be confined to only an individual afferent or can synapse upon several afferents.

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Structure and Growth of the Utricular Macula in the Inner Ear of the Slider Turtle Trachemys scripta

Cited by 19 publications

References 51 publications

Utricular afferents: morphology of peripheral terminals

Utricular afferents: morphology of peripheral terminals

Specializations of intercellular junctions are associated with the presence and absence of hair cell regeneration in ears from six vertebrate classes

Morphology of the utricular otolith organ in the toadfish, Opsanus tau

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