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At least 937 records · Page 52Linked to original sources
PubMedDate not supplied

High-resolution MR images of inner ear internal anatomy using a local gradient coil at 1.5 Tesla: correlation with histological specimen.

PURPOSE: To obtain high-resolution MR images of the inner ear at 1.5 Tesla with a local gradient coil and to correlate these images with the histological specimen. MATERIALS AND METHODS: All studies were performed on a 1.5 Tesla MR unit with a local gradient coil (23 mT/m, slew rate of 107 mT/m/ms). The cranio-facial region of a cadaver was examined using 3D-fast spin echo (FSE) imaging with the voxel size of 0.27 mm x 0.27 mm x 0.5 mm in 9 h 37 min. Two normal volunteers were examined with the same system using 3D-FSE imaging with the voxel size of 0.20 mm x 0.26 mm x 1.0 mm in 57 min. These images were correlated with the cadaver images and histological specimens. RESULTS: On cadaver images, internal structures such as the macula utriculi, macula sacculi, crista ampullaris, lamina spiralis ossea, ligamentum spirale cochleae, modiolus, scala tympani, scala vestibuli, and cochlear aqueduct were visualized. On the images of both volunteers, the same structures were visualized as on the cadaver images. CONCLUSIONS: This study confirmed that high-resolution MR images obtained at 1.5 Tesla can visualize inner ear internal anatomy. Knowledge obtained in this study may be of significant value for the diagnosis of pathology in the area of the inner ear.

Aged↗
PubMedDate not supplied

Expression of subtypes NF-L, NF-M and NF-H of neurofilament triplet proteins in the developing rat inner ear.

The expression of each subtype (NF-L, NF-M and NF-H) of neurofilament (NF) triplet proteins in the developing rat inner ear was analysed using the immunofluorescence method (FITC). On the 15th gestational day (GD), immunostaining of NF subtypes did not occur in the otic region. On the 18th GD, positivity for NF-L and NF-M occurred in nerve fibres in both the sensory and the subepithelial layers of the inner ear but was lacking for NF-H. At 4 days after birth immunoreactivity was present for each NF subtype but with topographic differences in their distribution. The cell bodies of (different?) subpopulations of vestibular and spiral ganglion cells were immunostained with monoclonal antibodies for NF-L and NF-M, but a subpopulation of both vestibular and spiral ganglion cells showed immunoreactivity for all three NF subtypes. The vestibular nerve fibres and ganglion cells evidenced stronger positivity than cochlear nerve fibres and spiral ganglion cells. This study confirms that the cytoskeletal maturation of inner ear nerve fibres precedes the onset of at least the auditory function by several days.

Animals↗
PubMed1977

Neuroanatomical aspects of the gerbil inner ear: light microscope observations.

A specialization of the Mongolian gerbil inner ear allows easy access for electrophysiological recording from the auditory nerve and other structures of the internal auditory meatus. The round-window membrane is recessed, creating a cavity connecting the bulla and the external wall of the modiolus. This cavity has been named the round-window antrum. A small opening made in the dorsomedial wall of the round-window antrum gives access directly to the modiolus and internal auditory meatus, with no other openings in the cranium required. This surgery is less drastic than that needed for similar access in most other mammals. The anatomy of the specialized region is presented from studies with the light microscope. Emphasis is placed on the relationship between external features of the wall of the round-window antrum and the internal anatomy of the modiolus and internal auditory meatus. In addition, these studies reveal that cell bodies of the acoustic-nerve nucleus are located in the auditory nerve, central to the glial dome. About 22 +/- 8 cells are found in an auditory nerve. Their appearance with a Nissl stain is similar to cells found in rat, mouse, and man. The cell dendrites are preferentially oriented perpendicular to the longitudinal course of the auditory-nerve fibers. The anatomy of the gerbil auditory system should allow direct electrophysiological recording from these cells.

Animals↗
PubMed1993

Zebrafish inner ear sensory surfaces are similar to those in goldfish.

The inner ear of the zebrafish (Brachydanio rerio) is very similar to that of the goldfish in its structural details, including the distribution and orientation of mechanosensory hair cell populations. Both species have been used in studying different aspects of the acoustic startle response. These structural similarities suggest that the zebrafish is a valid representative model for understanding peripheral hearing specializations in otophysan fishes.

Acoustic Stimulation↗
PubMed1993

Congenital cerebrospinal fluid fistula through the inner ear and meningitis.

Congenital deformities of the labyrinth of the inner ear can be associated with a fistulous communication between the intracranial subarachnoid space and the middle ear cavity. We describe seven such cases, six confirmed by high resolution CT and one by postmortem histological section. The seven patients all presented with meningitis although a cerebrospinal fluid fistula was demonstrated at subsequent surgery or postmortem. The lesions were bilateral in three patients, unilateral in three and probably bilateral in the postmortem case although only one temporal bone was obtained. In every case there was a dilated sac instead of the normal two and a half turn cochlea on the affected side and this was confirmed at surgery. The demonstration of the basal cochlear turn is of paramount importance in any deaf child presenting with meningitis. A true Mondini deformity with a normal basal turn and some hearing is not at risk of developing a fistula.

Adult↗
PubMed1977

[Otosclerosis involving the capsule and inner ear. Morphological findings (author's transl)].

The problem of otosclerotic inner ear damage is considered on the basis of morphological findings. It is pointed out that the disease of the otic capsule certainly also affects the underlying sense organ. This arises through disturbance of the perilymphatic electrolytes, venous stasis and thus changes in the circulation, disturbed regulation of endolymph and, more rarely, the direct effect of the focus on the auditory nerve or calcification of the mobile membranes.

Basilar Membrane↗
PubMed1992

Inner ear barotrauma: a case for exploratory tympanotomy.

A case of inner ear barotrauma (IEBT) due to an hypobaric chamber experience is presented. IEBT is an exceedingly rare condition in aviation. In the case described, the diagnosis was initially unsuspected due to accompanying middle ear barotrauma. The underlying etiology, the diagnosis, and management of IEBT are discussed.

Adult↗
PubMed1995

The glycan keratan sulfate in inner ear crystals.

The otoconial matrix (OM) of chicks (Gallus domesticus) inner ear was analyzed. Histochemically the OM was reacted with phosphotungstic acid (PTA) and immunohistochemically with the monoclonal antibody antikeratan sulfate (antiKS). The OM was digested with the enzyme endo-beta-galactosidase (E beta Galase) or separated by 1D and 2D gel electrophoresis. PTA which reacts with glycoproteins precipitated the OM, suggesting that the OM contains glycoproteins. A central core in each crystal had no PTA staining, suggesting that the core lacked glycoproteins. Anti KS antibody stained the OM with increased density in older embryos as determined by color thresholding. E beta Galase, which cleaves the lactosamine repeating units in KS, decreased the immunostain by 30% in the OM and by 20% in the cartilage. The OM from the utricle, saccule and macula lagena contained similar molecular weight bands. Five dense bands in the OM were less dense in tissue and blood controls, suggesting that such bands are enriched in the OM. Isoelectric focusing of the OM showed a negatively charged high molecular weight smear not present in blood and faint in tissue controls. The high affinity of the OM for the cationic PTA stain, the strong immunohistochemical reaction of the OM with anti KS antibody and high molecular weight negative smear in 2D gels taken together suggest that: a) the OM contains large amounts of glycoproteins and glycans, one of which is keratan sulfate, because its immuno stain with antiKS antibody was decreased by the enzyme E beta Galase, b) the utricle, saccule and macula lagena may have similar composition, and c) the concentration of KS may increase gradually until complete mineralization of the OM is reached.

Animals↗
PubMed1997

The role of neurotrophic factors in regulating the development of inner ear innervation.

Several neurotrophins and their receptors regulate the survival of vestibular and cochlear neurons and probably also the efferent and autonomic neurons that innervate the inner ear. Mice lacking either brain-derived neurotrophic factor (BDNF) or its associated receptor, TrkB, lose all innervation to the semicircular canals and have reduced innervation of the outer hair cells in the apical and middle turns of the cochlea. Mice lacking neurotrophin-3 (NT-3) or its receptor, TrkC, lose many spiral ganglion cells predominantly in the basal turn of the cochlea. Nerve fibers from spiral ganglion cells in the middle turn extended to inner hair cells of the base. In mice lacking both BDNF and NT-3, or both TrkB and TrkC, there is a complete loss of innervation to the inner ear. Thus, these two neurotrophins and their associated receptors have been shown to be absolutely necessary for the normal development of afferent innervation of the inner ear. Current research efforts are testing the therapeutic potential for neurotrophins to treat hearing loss.

Animals↗
PubMedDate not supplied

The effect of ultrasonic irradiation on the structural integrity of the inner ear labyrinth.

The histological appearance of the inner ear labyrinth was examined following ultrasonic irradiation of the vestibule and the cochlea in cats and guinea pigs. Directing ultrasound through the round window towards the ampulla of the superior semicircular canal produced severe balance dysfunction together with histological damage throughout the vestibular labyrinth. Cochlear damage was restricted to a small region of the basilar membrane proximal to the round window. When ultrasonic energy was directed into the cochlea cellular disruption extended over an area of at least two cochlear turns and included changes in the stria vascularis as well as to hair cells. The outer hair cells were found to be more sensitive than the inner hair cells to the damaging effects of ultrasound.

Animals↗
PubMed2003

[HRCT imaging characterized of congenital abnormalities of the inner ear in 45 cases].

OBJECTIVE: To explore the high resolution CT (HRCT) image characterized of congenital abnormalities of the inner ear(CAIE), and its value in the diagnosis and treatment of CAIE. METHOD: The clinic data and axial HRCT scans of CAIE in 45 cases were analyzed. RESULT: In 45 CAIE patients, most of them were frequently associated with slowly progressive sensorineural hearing loss in childhood, 15 ears were fluctuating hearing loss. Seventeen ears were unilateral semicircular canal paralysis. HRCT showed that Michel type 3 cases(4 ears), Mondini type 25 cases(39 ears). Large vestibular aqueduct malformation not associated with anomalies of inner ears 13 cases(23 ears), anomalies of internal auditory canal 4 cases (5 ears). Thirteen ears were associated with outer and middle ear malformation. CONCLUSION: HRCT image has the important value in the diagnosis and treatment of CAIE, especially for the excerpt of indication of cochlear implantation.

Adolescent↗
PubMed1995

Expression of intercellular adhesion molecule-1 during inner ear inflammation.

This study was designed to investigate the expression of intercellular adhesion molecule-1 (ICAM-1) on the spiral modiolar vein (SMV) with its collecting venules (CVs) and the venules of the endolymphatic sac during inner ear inflammation. These data will further elucidate the role of adhesion molecules in extravasation of inflammatory cells from blood vessels during an inner ear immune response. Labyrinthitis was induced in rats by inoculation of keyhole limpet hemocyanin into the scala tympani of animals who had been systemically sensitized to it. Expression of ICAM-1 was examined with a mouse monoclonal antibody to rat ICAM-1 by immunohistochemistry. ICAM-1 was found weakly on the epithelium of SMVs and CVs as early as 6 hours postchallenge, reaching a maximum by day 2 and then fading away gradually. The maximum influx of immunocompetent cells into the cochlea was seen between days 3 and 7. Staining for ICAM-1 was observed on the epithelium of the endolymphatic sac and perisaccular region at 12 and 24 hours, respectively, and this was associated with infiltration of cells into these areas 3 days postchallenge. By day 28, the inner ear had developed endolymphatic hydrops, but at this time it showed almost no significant staining with anti-ICAM-1. The molecule was also expressed in the mesothelium of perilymph, the perineurium of cochlear nerves, the spiral ligament, and the basal cells of the stria vascularis following immunization. Our data provide evidence that endothelial cells of the SMV and its CVs, as well as other inner sites, have the potential to express ICAM-1. This expression precedes the influx of immune cells; therefore, it is possible that this ligand plays a pivotal role in the onset of inflammation in the inner ear. This study also confirmed that the immune response results in endolymphatic hydrops as a long-term consequence.

Animals↗
PubMed1996

Pax2 contributes to inner ear patterning and optic nerve trajectory.

During gestation, the paired box-containing gene Pax2 is expressed in the mid-hindbrain area, developing eye and inner ear. We generated Pax2 null mutant mice, which show the requirement of Pax2 for the establishment of axonal pathways along the optic stalks and ventral diencephalon. In mutant brains, the optic tracts remain totally ipsilateral due to agenesis of the optic chiasma. Furthermore, Pax2 mutants show extension of the pigmented retina into the optic stalks and failure of the optic fissure to close resulting in coloboma. In the inner ear, Pax2 mutants show agenesis of the cochlea and the spiral ganglion, i.e., the parts of the organ responsible for auditory function and in whose primordium Pax2 is expressed. Our results identify Pax2 as a major regulator of patterning during organogenesis of the eye and inner ear and indicate its function in morphogenetic events required for closure of the optic fissure and neural tube.

Animals↗
PubMed2000

Mechanics of the inner ear of the bullfrog (Rana catesbeiana): the contact membranes and the periotic canal.

The frog inner ear consists of a complex of fluid-filled membranous sacs and canals containing eight distinct clusters of sensory hair cells. In this study we attempt to delineate the potential pathways for acoustic energy flow toward two of these clusters located within the amphibian papilla and the basilar papilla. Detailed morphological measurements of the periotic canal based on internal casts of the inner ear in the bullfrog (Rana catesbeiana) revealed that it is divided into a wide, tapered section and a narrower section comprised of two branches one short and blind projecting into the endolymphatic space and another longer, terminating in the round window. Additionally, we used laser Doppler velocimetry to record the velocity responses of the contact membranes of the amphibian papilla and basilar papilla. We found that the acoustic energy flow through these two structures is frequency dependent such that the amphibian papilla contact membrane displays a peak velocity amplitude at frequencies less than 500 Hz, whereas the basilar papilla contact membrane velocity response exhibits a maximum above 1,100 Hz. Our data advocate a mechanical substrate underlying the frequency segregation in the auditory nerve fibers innervating the amphibian papilla and the basilar papilla.

Animals↗
PubMed2003

A subpopulation of dorsal raphe nucleus neurons retrogradely labeled with cholera toxin-B injected into the inner ear.

Previous studies have shown that: (1) raphe neurons respond to acoustic and vestibular stimuli, some with a latency of 10-15 ms; (2) alterations of the raphe nuclei alter the acoustic startle reflex; (3) the dorsal raphe nucleus (DRN) is the major source of serotonergic neurons; and (4) approximately 57% of the DRN neurons are nonserotonergic. In the present study, cholera toxin subunit-B (CTB) was injected into cat cochleas, and the brain tissue was examined after a survival period of 5-7 days. Aside from neurons which were known to project to the inner ear, i.e., olivocochlear and vestibular efferent neurons, a surprising new finding was made that somata of a subpopulation of DRN neurons were intensely labeled with CTB. These CTB-labeled neurons were densely distributed in a dorsomedian part of the DRN with some in a surrounding area outside the DRN. The present results suggest that a novel raphe-labyrinthine projection may exist. A future study of anterograde labeling with injections of a tracer in the DRN will be needed to establish the existence of a raphe-labyrinthine projection more thoroughly. A raphe-labyrinthine descending input, together with an ascending input from the inner ear to the DRN through intervening neurons, such as the juxta-acousticofloccular raphe neurons (JAFRNs) described by Ye and Kim, may mediate a brain stem reflex whereby a salient multisensory (including auditory and vestibular) stimulus may alter the sensitivity of the inner ear. As a mammal responds to a biologically important auditory-vestibular multisensory event, the raphe projections to the inner ear and other auditory and vestibular structures may enhance the mammal's ability to localize and recognize the sound and respond properly. The raphe-labyrinthine projection may also modulate the inner ear's sensitivity as a function of the sleep-wake arousal state of an organism on a slower time course.

Animals↗
PubMed1988

Congenital middle and inner ear anomalies.

For this study, 100 human temporal bones from 73 individuals, aged 31 gestational weeks to 39 years, each with anomalies of the middle and/or inner ear, were studied to identify the features, locations, and frequencies with which congenital anomalies occurred in these structures. The temporal bones had been removed at autopsy, fixed, dehydrated, embedded in celloidin, sectioned horizontally or vertically at 20 microns, stained with hematoxylin and eosin, and studied under a light microscope. The anomaly in the middle ear most often found was wide dehiscence of the facial canal; hypoplastic cochlea was most frequently observed anomaly in the inner ear. The implications of these findings for development of the ear during fetal life are discussed.

Ear, Inner↗