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At least 811 records · Page 45Linked to original sources
PubMed2002

Atlas of the developing inner ear in zebrafish.

This report provides a description of the normal developing inner ear of the zebrafish, Danio rerio, with special focus on the pars inferior. Zebrafish specimens, ranging in age from 3 to 30 days postfertilization (dpf), were processed for standard histologic sections or with a paint-fill method to show three-dimensional morphogenesis of the membranous labyrinth. Adult zebrafish (age 2 years) were also processed for inner ear paint-fills. Although development of the semicircular canals occurs rapidly (by 3 dpf), the pars inferior develops more gradually during days 5-20 postfertilization. A rudimentary endolymphatic duct emerges by 8 dpf. Differentiated hair cells of the lagenar macula are evident by 15 dpf, in a chamber located lateral and posterior to the saccule. By 20 dpf, the saccule itself is separated from the utricle, but remains connected by means of the utriculosaccular foramen. The maculae neglectae, each with differentiated hair cells, lie on the floor of the utricle near this foramen. A medial connection between the sacculi of right and left ears, the transverse canal, is also complete by 20 dpf. A ridge of mesenchyme, previously undescribed, bisects the saccule in zebrafish fry at 20-30 dpf. The images in the paint-fill atlas should provide a baseline for future studies of mutant zebrafish ears.

Animals↗
PubMed1997

Minute findings of inner ear anomalies by three-dimensional CT scanning.

In actual clinical situations, inner ear anomalies must be diagnosed by image diagnosis such as high resolution CT-scanning of the temporal bone before three dimensional (3D) CT-scanning was introduced. In this paper, the usefulness of 3D-CT was investigated in some anomaly cases. It was found that 3D-CT was useful in observing the minute structure of the inner ear in that it could ascertain spatial relationships and minute constrictions and protrusions that could not be detected by 2D analysis. This CT was also capable of assessing the stage of embryological injuries and evaluating anomalies in cochlear turning that are the hidden factors of hearing impairment.

Adolescent↗
PubMed2005

Usherin, the defective protein in Usher syndrome type IIA, is likely to be a component of interstereocilia ankle links in the inner ear sensory cells.

Usher syndrome type IIa (USH2A) combines moderate to severe congenital hearing impairment and retinitis pigmentosa. It is the most common genetic form of USH. USH2A encodes usherin, which was previously defined as a basement membrane protein. A much larger USH2A transcript predicted to encode a transmembrane (TM) isoform was recently reported. Here, we address the role of TM usherin in the inner ear. Analysis of the usherin alternative transcripts in the murine inner ear revealed the existence of several predicted TM usherin isoforms with modular ectodomains of different lengths. In addition, we identified in the usherin cytoplasmic region a predicted 24 amino acid peptide, derived from a newly defined exon that is predominantly expressed in the inner ear but not in the retina. In mouse and rat inner ears, we show that TM usherin is present at the base of the differentiating stereocilia, which make up the mechanosensitive hair bundles receptive to sound. The usherin immunolabeling is transient in the hair bundles of cochlear hair cells (HCs), but persists in mature hair bundles of vestibular HCs. Several lines of evidence support the involvement of TM usherin in the composition of the ankle links, a subset of filamentous lateral links connecting stereocilia at the base. By co-immunoprecipitation and in vitro binding assays, we establish that the usherin cytodomain can bind to whirlin and harmonin, two PDZ domain-containing proteins that are defective in genetic forms of isolated deafness and USH type I, respectively. These PDZ proteins are suitable to provide the anchoring of interstereocilia lateral links to the F-actin core of stereocilia. Our results strongly suggest that congenital deafness in USH type I and type II shares similar pathogenic mechanisms, i.e. the disruption of hair bundle links-mediated adhesion forces that are essential for the proper organization of growing hair bundles.

Alternative Splicing↗
PubMed2006

[The application of the magnetic resonance hydrography of inner ear in diagnosing large vestibular aqueduct syndrome].

OBJECTIVE: To study the effect of the magnetic resonance hydrography of inner ear technique in diagnosing large vestibular aqueduct syndrome. METHOD: 3D-Fast Advanced Spin Echo MR imaging was performed on the petrosal bone of the patient who suffered from large vestibular aqueduct syndrome(LVAS). Then all the original images were transferred to an online workstation and underwent image postprocessing. The 3D images of the inner ears were obtained after 3D reconstruction. RESULT: The MR hydrography of inner ear of the patient displayed that there was an extradural high-signal intumescence which was like silver shape and the edge of it was smooth and neat between the sigmoid sinus of the posterior cranial fossa and the inner acoustic meatus. The maximum width of the mid position of endolymphatic sac in the temporal bone of the patient was 2.470 mm. This was much bigger than the diagnosis standard of the large vestibular aqueduct syndrome with ordinary MR imaging. CONCLUSION: The MR hydrography technique is an effective method to diagnose large vestibular aqueduct syndrome. The final diagnosis in clinic could be made with the assistance of this technique.

Adult↗
PubMed1996

[Studies on the fine structures of inner ear vessels in guinea pigs].

In order to investigate the characters of inner ear vessels using the microvascular corrosion casting technique and scanning electron microscope the three-dimensional spatial picture of the vessels in cochlear basilar membrane, utriculus, sacculus and three ampullae of guinea pig were observed. It was found that arteriole coils were present in the modiolus ampullae, utriculus and sacculus. The length of arterioles was therefore prolonged and could keep the blood supply in inner ear stable. The possibility of blood coagulation in these segments increased because the blood flow became slower here. Another character was that the capillary networks appeared denser in stria vascularis and central part of the crista, whereas the vessel meshes in basilar membrane of cochlea and in planum semiculatum of ampullae were looser. These findings suggested that the metabolism in stria vascularis and central part of the crista would be more prosperous than that in the basilar membrane and planum semiculatum of ampullae.

Animals↗
PubMed1996

Sensory organ generation in the chick inner ear.

There are a total of eight sensory organs in the chick inner ear. Each sensory organ has a distinct structure tailored for its function, and its morphology is well characterized. However, the origin of these sensory organs and the lineage relationships among them are largely unknown. In this report, we show that BMP4 (bone morphogenetic protein), a secreted protein of the TGF-beta gene family, is the earliest sensory marker identified to date for the chick inner ear. In addition to BMP4, we show that Msx-1 is a sensory marker for the three cristae, the lagena, and macula neglecta. P75NGFR (nerve growth factor receptor) is a marker for the three cristae only. Based on the expression pattern of these three genes-BMP4, Msx-1, and p75NGFR-it is estimated that the first sensory organs to be generated were the superior and posterior cristae at stage 19, followed by the macula sacculi at stage 20, the lateral crista at stage 22, the basilar papilla and lagena at stage 23, the macula utriculi at stage 24, and the macula neglecta at stage 29. The age of generation of each sensory organ as defined by the first appearance of these molecular markers is well in advance of the histological differentiation. In addition, the differential gene expressions in each presumptive sensory organ may contribute to the distinct structure of the mature organ.

Animals↗
PubMed1990

The influence of portocaval shunting on inner ear structures.

In rats with a portocaval shunt the cells of the inner ear were examined in an ultrastructural study. In 15 rats a porto-caval shunt (PCS) was constructed. Control rats underwent identical procedures but no anastomosis was produced (SOP). The control rats were pair-feeded. PCS rats developed an increased urinary zinc excretion associated with weight loss, alopecia, lethargy and atrophy of the testes. The serum zinc concentration in PCS rats was significantly reduced. In the inner ear we found ultrastructurally an increasing number of lysosomes and a severe damage of the myelin sheath of the granular ganglion cells. The myelin sheath was split and filled with great myelin figures. In the outer hair cells resulted in an increasing number of lysosomes. In the stria vascularis and in Reissner's membrane a vacuolization of the tissue appeared. The results of this study show that rats with a porto-caval anastomosis serve as a pathophysiological model of zinc impoverishment like porto-caval shunting in patients with liver cirrhosis.

Animals↗
PubMed1991

Expression of intermediate filament proteins in the mature inner ear of the rat and guinea pig.

The expression of intermediate filament proteins was studied in the mature inner ear of the rat and guinea pig, using a panel of polyclonal and monoclonal antibodies directed against cytokeratins, desmin, neurofilament proteins and glial fibrillary acidic protein (GFAP). The epithelial lining of the endolymphatic space displayed a complex expression pattern of cytokeratin filament proteins, suggesting greater cell diversity than was known sofar from morphological studies. The cytokeratin antibodies when applied to the inner ear tissues revealed the presence of only cytokeratin polypeptides which are typical of simple epithelia (i.e. nos. 7, 8, 18, and 19). Profound differences in cytokeratin expression patterns were, however, found in the various cell types of both the cochlear and vestibular partition. Remarkably, the sensory cells appeared to be devoid of both cytokeratins and neurofilament proteins. Staining with a 200 kDa neurofilament antibody displayed the presence of different populations of ganglion cells in the spiral ganglion and the vestibular ganglion. There was no reaction with antibodies directed against desmin and GFAP. The great resemblance of the intermediate filament protein expression patterns in the inner ear of the rat and guinea pig indicates a close similarity between the different epitopes.

Animals↗
PubMed2000

Perilymphatic fluid compartments and intercellular spaces of the inner ear and the organ of Corti.

An in vitro preparation of the inner ear cochlea has been used to visualize the structural relationships of unfixed, living sensory cells and structural components within the intact hearing organ. By perfusing perilymphatic compartments of the cochlea with fluorochrome-conjugated dextran, the extracellular spaces were clearly outlined. The staining pattern illustrated the large fluid compartments formed by the tunnel of Corti, the space of Nuel, and the outer tunnel. The dextran solution also indicated the spaces between the outer hair cell rows, the inner hair cells, and the surrounding supporting cells. The staining pattern demonstrates that the organ of Corti has a loose structure, suggesting a weak mechanical coupling between the cells. Moreover, it is evident that substances applied to the perilymph (e.g., therapeutic drugs) will readily reach all the cells of the hearing organ. In addition to the intraorgan fluid compartments, the spiral limbus was shown to contain significant volumes of perilymph within the intercellular spaces forming the so-called teeth of Huschke between the interdental cells. An extensive system of bundles following the teeth of Huschke was shown to be completely immersed in perilymph. The bundles were stained by a potentiometric dye, which in the inner ear primarily stains nerve fibers and sensory cells, which may indicate a nervous control of cells in this region.

Animals↗
PubMed2000

Detection of extracellular signal-regulated kinase1/2 in the inner ear of guinea pigs.

Growth factors, such as vascular endothelial growth factor (VEGF) and neurotrophins, recently identified in the inner ear of guinea pigs, exert their proliferative properties partly through activation of mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK1/2). In order to demonstrate presence of ERK1/2 in the inner ear we performed immunohistochemical analysis using specific antibodies to inactive and activated ERK1/2 on paraffin-sections of temporal bones from guinea pigs (n=5). In the cochlea clear immunoreactivity to inactive ERK1/2 was predominant in the spiral ligament, in the organ of Corti (intensive staining in supporting cells, faint staining in sensory cells) and limbus epithelium, while spiral ganglion cells and nerve fibres revealed weak staining. Activated ERK1/2 could be detected sparely in the spiral ligament exclusively. In the vestibule inactive ERK1/2 was located in the sensory epithelium, in nerve fibres and in vascular endothelium, while activated ERK1/2 could be detected in few nerve fibres and synaptic endings (buttons and calyces) on hair cells of the maculae and crests and in the endothelium of few blood vessels. These findings provide evidence that activated ERK1/2, as a general downstream signal of growth factors, may be contributed in the inner ear physiology.

Animals↗
PubMedDate not supplied

Unilateral complete aplasia of the inner ear with associated tracheoesophageal fistula: report of a case.

A case of unilateral complete aplasia of the petrous apex and inner ear associated with H-type tracheoesophageal fistula is reported. polytomography, computerized axial tomography, and plain film radiography confirmed the presence of this rare variant of inner ear aplasia. This patient, who has normal facial nerve function, is, to our knowledge, the first reported case of a nonthalidomide, Michel-type aplasia since the original report of Michel more than a century ago. Unilateral complete inner ear aplasia associated with tracheoesophageal fistula has not been previously reported.

Child↗
PubMedDate not supplied

Distribution of hyaluronan in the middle and inner ear. A light microscopical study in the rat using a hyaluronan-binding protein as a specific probe.

The histochemical distribution of hyaluronan (hyaluronic acid, HYA) was analyzed in middle and inner ear tissues from rats by use of microwave-aided fixation, a hyaluronan-binding protein and the avidin-biotin/peroxidase staining procedure. In the middle ear HYA was mainly localized in the pars flaccida, the ossicles, the round window membrane and in the endomysium of the middle ear muscles. The subepithelial stroma of the Eustachian tube was strongly HYA-positive. In the inner ear, the spiral ligament of the cochlea and the connective tissue surrounding the nerve fibers emerging from the crista ampullaris stained intensely for HYA. Except for a weak staining of the basilar membrane, the Corti organ was devoid of HYA. The heterogenous distribution of HYA may indicate its specific involvement in middle and inner ear physiology and pathology.

Animals↗
PubMed1987

Congenital malformations of the inner ear: a classification based on embryogenesis.

Approximately 20% of patients with congenital sensorineural hearing loss have radiographic abnormalities of the inner ear. A broad spectrum of anomalous patterns have been described, most of which have been lumped together under the term "Mondini's dysplasia." We feel that this grouping of many dissimilar entities under a single umbrella term is unwarranted. Based on a review of 63 patients with 98 congenitally malformed ears, we have been able to recognize a number of distinct anatomic patterns from their radiographic appearance. A remarkable similarity between these morphologies and the appearance of the inner ear at various stages of embryogenesis was found. This led us to propose a classification system based upon the theory that these deformities result from an arrest of development during varying stages of inner ear organogenesis.

Congenital Abnormalities↗
PubMed1980

Pathophysiology of inner ear dysfunction in the squirrel monkey in rapid decompression.

More than 90 squirrel monkeys with bilateral myringotomies (a small hole in each ear drum) were rapidly decompressed in a hyperbaric chamber according to a special diving profile in which 35% of attempts produced disorders ("hits") confined to the inner ear. Monkeys receiving inner ear hits (as determined by the sudden onset of vigorous head or eye nystagmus during decompression) were tested and killed at times ranging from 1 h to more than 12 mo following the dive. Histologically, in monkeys killed 1 mo or less after the hit, hemorrhage and/or a deep purple-staining precipitated material were frequently found in the otic fluid spaces. In those monkeys killed more than 1 mo after a hit, ectopic new bone growth in the arms of the semicircular canals was a common sequela. New bone growth never appeared in the cochlea. In unaffected ears, and in both ears of control animals, the precipitated material was somewhat less than in ears damaged by decompression; and, furthermore, new bone growth did not occur. Behaviorally, the hit monkeys showed vestibular deficits that were consistent with the structural damage revealed by histology.

Animals↗
PubMed1984

Inner ear anomalies in Waardenburg's syndrome associated with Hirschsprung's disease.

Congenital inner ear anomalies are reported in temporal bones of a 22-month-old boy with Waardenburg's syndrome and Hirschsprung's disease. Although no changes in the central auditory pathway were identified, peripheral lesions of the cochlear and vestibular membranous labyrinth were observed. Bilateral atrophy of the organ of Corti and stria, and a sparsity of spiral ganglion cells were observed in the cochlea. Degeneration of the vestibular end organs, including a loss of Scarpa's ganglion cells, was also seen. This is the first report of temporal bone histopathology associated with Waardenburg's syndrome and Hirschsprung's disease. The pathoembryology of these inner ear anomalies associated with aganglionosis of the colon supports the hypothesis that Waardenburg's syndrome and Hirschsprung's disease are hereditary defects of neural crest cells.

Abnormalities, Multiple↗
PubMed1986

Lightning causing inner ear damage and intracranial haematoma.

Lightning can transmit energy by way of the telephone network to the middle and the inner ear and thus cause pronounced injuries. In the patient mentioned here, the middle ear remained intact, while the inner ear was the seat of widespread damage combined with vascular rupture, the latter causing the formation of an intracranial haematoma. This was originally interpreted wrongly as a neoplasm.

Adult↗
PubMed1991

[Electron microscopic study on inner ear barotrauma: with emphasis on the cochlear damage].

In order to investigate inner ear barotrauma, guinea pigs were subjected to rapid decompression between 2 absolute pressure (ATA) and 1 ATA in a chamber. After pressure loading and observation for absence of Preyer's reflex, they were sacrificed immediately, 1 day, 1 week and 1 month later, respectively. Then, morphological changes of the organ of Corti and stria vascularis were studied under TEM and SEM. The immediate features noted were fracture of stereocilia with minimal intracellular changes. One day later, there was marked degeneration of outer hair cells and expansion of supporting cells. The damage to stereocilia clearly preceded morphological alterations within hair cell bodies and cannot be interpreted as arising secondary to hair cell degeneration. Most of outer hair cells eventually disappeared and were replaced by supporting cells. Inner hair cells degenerated slowly; 1 month later, some of them remained almost intact, despite disappearance of stereocilia. The continuity of reticular lamina was maintained not only immediately but also through the period of hair cell degeneration, thus preventing any leakage of endolymph into the organ of Corti. There was reversible dendritic swelling of inner hair cells immediately following the trauma. No changes of stria vascularis were observed over passage of time. The mechanism of hair cell damage due to inner ear barotrauma is presumed to be a deformity of the organ of Corti caused by pressure discrepancy between perilymph and endolymph resulting in an injury to stereocilia.

Animals↗
PubMed1985

Carbonic anhydrase activity in the inner ear.

The histochemical and cytochemical localization of carbonic anhydrase activity in the inner ear of guinea pig was studied with Hansson's method and modified Yokota's method. All cells possessing the cell membrane infoldings are proved to have the enzymatic activity. The cochlear hair cells show strong enzymatic activity while the vestibular hair cells show no appreciable activity. The supporting cells of both cochlear and vestibular hair cells also show the enzymatic activity. The reaction products showing the enzymatic activity are observed in the cytoplasm, nucleus and cell membrane of the stained cells with both light microscope and electron microscope. The stria vascularis, vestibular dark cells and endolymphatic sac are proved to have the enzymatic activity. The cells, which are already proved to have Na+-K+-ATPase activity, show the enzymatic activity. The regulation of the fluid and ion in the inner ear is probably a complex mechanism involving not only various cells but also several enzymes such as carbonic anhydrase, Na+-K+-ATPase and adenylate cyclase.

Animals↗