Acoustic Maculae
Macula Lutea
An oval area in the retina, 3 to 5 mm in diameter, usually located temporal to the posterior pole of the eye and slightly below the level of the optic disk. It is characterized by the presence of a yellow pigment diffusely permeating the inner layers, contains the fovea centralis in its center, and provides the best phototropic visual acuity. It is devoid of retinal blood vessels, except in its periphery, and receives nourishment from the choriocapillaris of the choroid. (From Cline et al., Dictionary of Visual Science, 4th ed)
Age-related blood flow and capillary changes in the rat utricular macula: a quantitative stereological and microsphere study. (1/15)
Vascular change may contribute to age-related vestibular dysfunction. Previously, we reported a significant age-related decrease in blood flow (BF) and mean capillary diameter (D(cap)) in the rat posterior canal crista. The purpose of this study was to examine an otolith organ, the utricle, for similar changes. Old male Fischer 344 rats (O; 28-31 mos) were anesthetized, and the left cardiac ventricle was transcutaneously injected with radioactive microspheres to determine BF. The temporal bones were removed, fixed, and decalcified. The utricles were dissected free and placed into a gamma counter with the reference samples. The specimens were then plastic embedded and serially sectioned at 1 microm according to the vertical section technique. Microsphere surface counts were made and neuroepithelial BF calculated. A systematic random set of sections was sampled and analyzed using stereological techniques for estimates of D(cap), capillary surface area/unit volume (S(v,cap)), capillary length/ unit volume (L(v,cap)), and volume of utricular neuroepithelium (V(ut)). Using these data, total capillary surface (S(cap)) and total length (L(cap)) were calculated. Statistical comparisons were made with data from our previous study of young animals (Y; 3-6 mos). Results indicate a significant age-related decrease in BF (Y = 0.125 microL/min, O = 0.062 microL/min; P = 0.003), D(cap) (Y = 5.95 micro, O = 4.57 microm; P = 0.0002), S(vcap) (Y = 12.33 mm2/mm3, = 9.87 mm2/mm3, P = 0.016), S(cap) (Y = 0.178 mm2, O = 0.129 mm2; p = 0.01), and V(ut) (Y = 0.014 mm3, O = 0.013 mm3; P = 0.04) with no significant change in L(v,cap) (Y = 655 mm/mm3, O = 686 mm/mm3, P = 0.41) or L(cap) (Y = 9.47 mm, O = 8.96 mm; P = 0.49). These age-related vascular changes are likely to have a significant impact on utricular physiological and thus, dysequilibrium. (+info)Afferent innervation patterns of the saccule in pigeons. (2/15)
The innervation patterns of vestibular saccular afferents were quantitatively investigated in pigeons using biotinylated dextran amine as a neural tracer and three-dimensional computer reconstruction. Type I hair cells were found throughout a large portion of the macula, with the highest density observed in the striola. Type II hair cells were located throughout the macula, with the highest density in the extrastriola. Three classes of afferent innervation patterns were observed, including calyx, dimorph, and bouton units, with 137 afferents being anatomically reconstructed and used for quantitative comparisons. Calyx afferents were located primarily in the striola, innervated a number of type I hair cells, and had small innervation areas. Most calyx afferent terminal fields were oriented parallel to the anterior-posterior axis and the morphological polarization reversal line. Dimorph afferents were located throughout the macula, contained fewer type I hair cells in a calyceal terminal than calyx afferents and had medium sized innervation areas. Bouton afferents were restricted to the extrastriola, with multi-branching fibers and large innervation areas. Most of the dimorph and bouton afferents had innervation fields that were oriented dorso-ventrally but were parallel to the neighboring reversal line. The organizational morphology of the saccule was found to be distinctly different from that of the avian utricle or lagena otolith organs and appears to represent a receptor organ undergoing evolutionary adaptation toward sensing linear motion in terrestrial and aerial species. (+info)Hair bundle heights in the utricle: differences between macular locations and hair cell types. (3/15)
Hair bundle structure is a major determinant of bundle mechanics and thus of a hair cell's ability to encode sound and head movement stimuli. Little quantitative information about bundle structure is available for vestibular organs. Here we characterize hair bundle heights in the utricle of a turtle, Trachemys scripta. We visualized bundles from the side using confocal images of utricular slices. We measured kinocilia and stereocilia heights and array length (distance from tall to short end of bundle), and we calculated a KS ratio (kinocilium height/height of the tallest stereocilia) and bundle slope (height fall-off from tall to short end of bundle). To ensure that our measurements reflect in vivo dimensions as closely as possible, we used fixed but undehydrated utricular slices, and we measured heights in three dimensions by tracing kinocilia and stereocilia through adjacent confocal sections. Bundle heights vary significantly with position on the utricular macula and with hair cell type. Type II hair cells are found throughout the macula. We identified four subgroups that differ in bundle structure: zone 1 (lateral extrastriola), striolar zone 2, striolar zone 3, and zone 4 (medial extrastriola). Type I hair cells are confined to striolar zone 3. They have taller stereocilia, longer arrays, lower KS ratios, and steeper slopes than do neighboring (zone 3) type II bundles. Models and experiments suggest that these location- and type-specific differences in bundle heights will yield parallel variations in bundle mechanics. Our data also raise the possibility that differences in bundle structure and mechanics will help explain location- and type-specific differences in the physiological profiles of utricular afferents, which have been reported in frogs and mammals. (+info)Regeneration of vestibular otolith afferents after ototoxic damage. (4/15)
Regeneration of receptor cells and subsequent functional recovery after damage in the auditory and vestibular systems of many vertebrates is well known. Spontaneous regeneration of mammalian hair cells does not occur. However, recent approaches provide hope for similar restoration of hearing and balance in humans after loss. Newly regenerated hair cells receive afferent terminal contacts, yet nothing is known about how reinnervation progresses or whether regenerated afferents finally develop normal termination fields. We hypothesized that neural regeneration in the vestibular otolith system would recapitulate the topographic phenotype of afferent innervation so characteristic of normal development. We used an ototoxic agent to produce complete vestibular receptor cell loss and epithelial denervation, and then quantitatively examined afferent regeneration at discrete periods up to 1 year in otolith maculas. Here, we report that bouton, dimorph, and calyx afferents all regenerate slowly at different time epochs, through a progressive temporal sequence. Furthermore, our data suggest that both the hair cells and their innervating afferents transdifferentiate from an early form into more advanced forms during regeneration. Finally, we show that regeneration remarkably recapitulates the topographic organization of afferent macular innervation, comparable with that developed through normative morphogenesis. However, we also show that regenerated terminal morphologies were significantly less complex than normal fibers. Whether these structural fiber changes lead to alterations in afferent responsiveness is unknown. If true, adaptive plasticity in the central neural processing of motion information would be necessitated, because it is known that many vestibular-related behaviors fully recover during regeneration. (+info)Zebrafish pax5 regulates development of the utricular macula and vestibular function. (5/15)
The zebrafish otic vesicle initially forms with only two sensory epithelia, the utricular and saccular maculae, which primarily mediate vestibular and auditory function, respectively. Here, we test the role of pax5, which is preferentially expressed in the utricular macula. Morpholino knockdown of pax5 disrupts vestibular function but not hearing. Neurons of the statoacoustic ganglion (SAG) develop normally. Utricular hair cells appear to form normally but a variable number subsequently undergo apoptosis and are extruded from the otic vesicle. Dendrites of the SAG persist in the utricle but become disorganized after hair cell loss. Hair cells in the saccule develop and survive normally. Otic expression of pax5 requires pax2a and fgf3, mutations in which cause vestibular defects, albeit by distinct mechanisms. Thus, pax5 works in conjunction with fgf3 and pax2a to establish and/or maintain the utricular macula and is essential for vestibular function. (+info)Architecture of the mouse utricle: macular organization and hair bundle heights. (6/15)
Hair bundles are critical to mechanotransduction by vestibular hair cells, but quantitative data are lacking on vestibular bundles in mice or other mammals. Here we quantify bundle heights and their variation with macular locus and hair cell type in adult mouse utricular macula. We also determined that macular organization differs from previous reports. The utricle has approximately 3,600 hair cells, half on each side of the line of polarity reversal (LPR). A band of low hair cell density corresponds to a band of calretinin-positive calyces, i.e., the striola. The relation between the LPR and the striola differs from previous reports in two ways. First, the LPR lies lateral to the striola instead of bisecting it. Second, the LPR follows the striolar trajectory anteriorly, but posteriorly it veers from the edge of the striola to reach the posterior margin of the macula. Consequently, more utricular bundles are oriented mediolaterally than previously supposed. Three hair cell classes are distinguished in calretinin-stained material: type II hair cells, type ID hair cells contacting calretinin-negative (dimorphic) afferents, and type IC hair cells contacting calretinin-positive (calyceal) afferents. They differ significantly on most bundle measures. Type II bundles have short stereocilia. Type IC bundles have kinocilia and stereocilia of similar heights, i.e., KS ratios (ratio of kinocilium to stereocilia heights) approximately 1, unlike other receptor classes. In contrast to these class-specific differences, bundles show little regional variation except that KS ratios are lowest in the striola. These low KS ratios suggest that bundle stiffness is greater in the striola than in the extrastriola. (+info)Resting discharge patterns of macular primary afferents in otoconia-deficient mice. (7/15)
(+info)Immunohistochemical localization and mRNA expression of aquaporins in the macula utriculi of patients with Meniere's disease and acoustic neuroma. (8/15)
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Miargyrite: Miargyrite mineral information and data.
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Macula
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செல்போன் கதிர்வீச்சு நம்மை தாக்காதவாறு தடுக்க சில வழிமுறைகள்
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Acoustic neuroma
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Saccule6
- Its anterior part exhibits an oval thickening, the macula of saccule (or saccular macula), to which are distributed the saccular filaments of the acoustic nerve. (wikipedia.org)
- The vestibule is a region of the inner ear which contains the saccule and the utricle, each of which contain a macula to detect linear acceleration. (wikipedia.org)
- The macula of saccule lies in a nearly vertical position. (wikipedia.org)
- The temporal bone contains the organs for hearing (i.e., organ of Corti) and the detection of gravity, linear and rotational motion (i.e., maculae of the utricule and saccule, cristae of the superior, lateral and posterior semicircular canals). (cdc.gov)
- The end organs for gravity and motion detection consist of five separate sensory organs: the macula of the utricule (pp 47 and 50) and macula of the saccule, both housed in the vestibule and three cristae, one in the ampullated end of the superior, lateral (or horizontal) and posterior semicircular canals (pp 48-50). (cdc.gov)
- acoustic spots macula of utricle, macula of saccule. (en-academic.com)
Saccular1
- The central part of the neurosensory area retains Sox3 but stops proliferating from stage 33, forming the first sensory areas (utricular/saccular maculae). (frontiersin.org)
Vestibular2
- Acoustic neuromas are intracranial, extra-axial tumors that arise from the Schwann cells, investing either the vestibular or cochlear nerve. (medscape.com)
- These results, together with evidence from patients with superior vestibular neuritis allow us to conclude: the asymmetry of the n10 response to Fz bone-conducted vibration is an indicator of utricular macula/superior vestibular nerve dysfunction on the operated side in patients with unilateral vestibular loss. (tampabayhearing.com)
Utricle1
- The macula of the utricle is in a horizontal position and detects horizontal acceleration. (wikipedia.org)
Neuroma3
- All patients with sudden SNHL should be imaged for work up of acoustic neuroma, even if they respond to steroids or their hearing spontaneously recovers. (medscape.com)
- A study by Foley et al of 945 persons with acoustic neuroma reported unilateral hearing loss to be the most common presenting system (80% of patients). (medscape.com)
- Disease entities of the inner ear include: congenital malformations, loss of sensory cells and nerve fibers (i.e., sensorineural hearing loss), cochlear otosclerosis, Meniere's disease, acoustic neuroma, or sudden hearing loss. (cdc.gov)
Sensory1
- The maculae (p 47) consist of flat plates of sensory (hair) and supporting cells. (cdc.gov)
Reflex3
- It has been known for a long time that the application of intense acoustic stimuli to the ear can induce reflex muscle responses. (neurootology.org)
- The classic physiology describes reflex responses of neck muscles aimed at turning the head towards the source of acoustic stimuli. (neurootology.org)
- It is believed that these muscles can contract to dampen the vibration of the ossicles, in order to protect the inner ear from excessively loud noise (theory 1) and that they give better frequency resolution at higher frequencies by reducing the transmission of low frequencies (theory 2) (see acoustic reflex ). (iiab.me)
Nerve2
Tumor2
- Acoustic neuromas are managed through microsurgical excision, by arresting tumor growth using stereotactic radiation therapy, or through serial observation. (medscape.com)
- Acoustic neuromas are managed in one of the following 3 ways: (1) microsurgical excision of the tumor, (2) arresting tumor growth using stereotactic radiation therapy, or (3) careful serial observation. (medscape.com)
Vibration1
- It can vastly enhance your vehicles sound upgrade by reducing sound vibration, eliminating outside road noise and creating a more acoustic environment, magnifying the sound quality of your system. (upgradekitfits.com)
Sudden1
- Though acoustic neuromas are generally slow-growing tumors and their associated hearing loss is usually progressive, they may also present with sudden sensorineural hearing loss (SNHL). (medscape.com)
Central1
- This refers to an acquired degeneration of the macula , which is the central area of the retina . (osmosis.org)
Sound2
- 4.5-metre (15 ft) high acoustic mirror near Kilnsea Grange, East Yorkshire, UK, from World War I . The mirror magnified the sound of approaching enemy Zeppelins for a microphone placed at the focal point . (wikipedia.org)
- An acoustic mirror reflects sound waves. (wikipedia.org)
Optical2
SACCULE AND UTR3
- We investigated how the macula and organization of auditory receptors in the saccule and utricle change during growth in this species. (usj.edu.mo)
- This is one of the first studies investigating the ontogenetic development of the saccule and utricle in a vocal fish and how it potentially relates to auditory enhancement for acoustic communication. (usj.edu.mo)
- The cristae of the three semicircular canals sense angular acceleration of the head (side-to-side or rotary), and the maculae of the saccule and utricle sense linear acceleration and gravity. (elquimdelaboqueria.com)
Auditory5
- auditory meatus acoustic meatus . (thefreedictionary.com)
- The auricle and external acoustic meatus (or external auditory canal) compose the external ear. (medscape.com)
- The external acoustic meatus (external auditory canal) is formed by cartilage and bone (temporal). (medscape.com)
- The mandibular condyle sits anterior to the bony portion of the external acoustic meatus (external auditory canal). (medscape.com)
- Intense noise levels (180 dB) destroy the hair cells of the auditory maculae resulting in hearing loss. (oceanmammal.org)
Epithelium1
- Nerve fibers enter the maculae from beneath the epithelium to innervate the hair cells. (cdc.gov)
Optic2
- Mouse embryo whole-mount and section in situ hybridization showed the expression of Chd7 in the outflow tract of the heart, optic vesicle, facio-acoustic preganglion complex, brain, olfactory pit, and mandibular component of the first branchial arch. (nih.gov)
- With this instrument, detailed findings of the posterior pole, the macula or the optic nerve can be displayed with great magnification. (heine.com)
Tympanic membrane1
- the external acoustic meatus leads from the auricle to the tympanic membrane (eardrum) and the internal acoustic meatus is for passage of nerves and blood vessels. (thefreedictionary.com)
Tumors5
- Acoustic neuromas account for approximately 80% of tumors found within the cerebellopontine angle. (medscape.com)
- The definitive diagnostic test for acoustic tumors is gadolinium-enhanced magnetic resonance imaging (MRI). (medscape.com)
- Though acoustic neuromas are generally slow-growing tumors and their associated hearing loss is usually progressive, they may also present with sudden sensorineural hearing loss (SNHL). (medscape.com)
- The definitive diagnostic test for patients with acoustic tumors is gadolinium-enhanced MRI. (medscape.com)
- Various surgical approaches can be used to remove acoustic tumors, including the translabyrinthine approach, the retrosigmoid approach, and the middle cranial fossa approach. (medscape.com)
Oval1
- They then transmit the amplified acoustic vibrations to the fluid of the inner ear via the oval window with minimal energy loss. (amboss.com)
Hair1
- In the centre of each macula is an area called the striola where hair cells are much less numerous, and the majority are type I. (vestib.org)
Occurs1
- Age-related macular degeneration is a disease against the macula of the retina that occurs with aging. (cmuh.org.tw)
Gravity1
- The temporal bone contains the organs for hearing (i.e., organ of Corti) and the detection of gravity, linear and rotational motion (i.e., maculae of the utricule and saccule, cristae of the superior, lateral and posterior semicircular canals). (cdc.gov)
Area2
- Saccular macula area expanded 41x in total, and significantly more (relative to body length) among vocal juveniles (2.3-2.9 cm). (usj.edu.mo)
- The macula is a small area in the most central part of the retina behind the eye. (cmuh.org.tw)
Surface2
- mks acoustic ohm *(Pa*s/m3) -of a surface for a given frequency, the complex quotient obtained when the sound pressure averaged over the surface is divided by the volume velocity through the surface. (avroomservice.com)
- The angle at which a light ray or acoustic wave strikes a surface, measured between the incoming wave and the line perpendicular to the surface. (avroomservice.com)
Study1
- Our study suggests that ETD and SOM cause irritation in children's ears that prompts them to put something in the ear to ease external acoustic meatus irritation. (thefreedictionary.com)
Portion2
- As acoustic neuromas enlarge, they eventually occupy a large portion of the cerebellopontine angle and cause hearing loss, dizziness, and tinnitus. (medscape.com)
- it consists of a bony (inner) portion and a fibrocartilaginous (outer) portion, the cartilaginous external acoustic meatus. (thefreedictionary.com)