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At least 613 records · Page 34Linked to original sources
PubMed2003

[Comparative anatomical study of the microvessel in chick cochlea].

OBJECTIVE: In order to providing information for related research, the ultrastructure of microvessel in chick cochlea was investigated. METHOD: Transmission electronic microscope and scanning electronic microscope were used to observe the ultrastructure of microvessel in cochleas of 10 chicks. RESULT: None typical blood capillary with thin--wall was found in chick cochleas, none microvessel was found within basilar membrane, the wall of microvessel in chick cochleas was thick, many lays of fibrils and pericytes and its processes were lined alternately from the endothelial cells to the peripheric basement membrane. Every fold of tegmentem vasculosum contained a microvessel. The ultrastructure of microvessel in spiral ganglion was similar to that of tegmentem vasculosum. The processes of pericyte were netted each other on the surface of microvessel. CONCLUSION: The ultrastructure and the distribution of microvessels in chick cochlea are differented significantly to that of cochlea in mammal. The significance should be investigated further.

Anatomy, Comparative↗
PubMed2003

Synchronization of a nonlinear oscillator: processing the cf component of the echo-response signal in the cochlea of the mustached bat.

Cochlear microphonic potential (CM) was recorded from the CF2 region and the sparsely innervated zone (the mustached bat's cochlea fovea) that is specialized for analyzing the Doppler-shifted echoes of the first-harmonic (approximately 61 kHz) of the constant-frequency component of the echolocation call. Temporal analysis of the CM, which is tuned sharply to the 61 kHz cochlear resonance, revealed that at the resonance frequency, and within 1 msec of tone onset, CM is broadly tuned with linear magnitude level functions. CM measured during the ongoing tone and in the ringing after tone offset is 50 dB more sensitive, is sharply tuned, has compressive level functions, and the phase leads onset CM by 90 degrees: an indication that cochlear responses are amplified during maximum basilar membrane velocity. For high-level tones above the resonance frequency, CM appears at tone onset and after tone offset. Measurements indicate that the two oscillators responsible for the cochlear resonance, presumably the basilar and tectorial membranes, move together in phase during the ongoing tone, thereby minimizing net shear between them and hair cell excitation. For tones within 2 kHz of the cochlear resonance the frequency of CM measured within 2 msec of tone onset is not that of the stimulus but is proportional to it. For tones just below the cochlear resonance region CM frequency is a constant amount below that of the stimulus depending on CM measurement delay from tone onset. The frequency responses of the CM recorded from the cochlear fovea can be accounted for through synchronization between the nonlinear oscillators responsible for the cochlear resonance and the stimulus tone.

Acoustic Stimulation↗
PubMed1992

CSF anatomy with emphasis on relations to nasal cavity and labyrinthine fluids.

Cerebrospinal fluid, occupying the subarachnoid space, is elaborated in an active process by the choroid plexus. It supports the brain and spinal cord and acts in lieu of a lymphatic system for central nervous tissue. Whether or not absorption of CSF into dural venous sinuses is an active or passive process is still controversial. A very thin layer of bone separates the posterior ethmoid air sinus from the subarachnoid space. There appears to be potential in man for flow of cerebrospinal fluid into the perilymphatic space of the inner ear, but it seldom occurs.

Animals↗
PubMed2004

[Quantification of endolymphatic hydrops in experimental animal model].

OBJECTIVE: To investigate a method of quantification of the endolymphatic hydrops in experimental animal model. METHODS: Thirty guinea pigs were divided into three groups at random. In control group, there were ten guinea pigs without operation on both ears. Endolymphatic hydrops was induced by endolymphatic sac obliteration through extradural posterior cranial fossa approach in right ear, including 4-week postoperative group(n = 10) and 8-week postoperative group(n = 10). The area of scala vestibuli (SV) and scala media(SM) of each turn on both cochlear midmodiolar sections was measured, respectively, using auto computer aided design(AutoCAD R14) software combined with digital camera, and then the maximum scala media area(SMA) ratio was calculated and compared. RESULTS: No endolymphatic hydrops was observed in all non-operated ears, however, variety degree of hydrops was present in all operated ears. The average maximum SMA ratio in the 4-week group (2.2231 +/- 0.1996) was greater than that in the control group (1.0971 +/- 0.0644). The average maximum SMA ratio of the 8-week group (4.0142 +/- 0.5218) was greater than that in the 4-weekgroup. There was significant difference between the two groups(P < 0.05). CONCLUSION: It is convenience and reliable to be used to quantify the experimental endolymphatic hydrops with the present method. This study provides a reliable methodological base for the experimental study of Meniere's disease.

Animals↗
PubMed1990

Morphology of synapses at the base of hair cells in the organ of Corti of the chimpanzee.

The synaptic morphology of inner and outer hair cells of the organ of Corti of the chimpanzee was evaluated by serial section electron microscopy. The morphology of nerve terminals and synapses at both sites was very similar to that of human and other mammalian species. Two types of nerve terminals, nonvesiculated and vesiculated, with distinct synaptic morphology were found. In addition, between some nonvesiculated endings and outer hair cells, a reciprocal synaptic relationship was seen. In such terminals there was morphologic evidence for transmission from hair cell to neuron and from neuron to hair cell between a single neuron and an outer hair cell.

Animals↗
PubMed1990

[The development of stria vascularis in the guinea pig fetus].

In the 25 day old guinea pig fetus the lateral wall of the ductus cochlearis is lined with a cylindrical epithelium consisting of a single layer of columnar cells, which opens onto the endolymphatic space. It is clearly separated from the adjacent structures by a basal membrane. This connective tissue contains numerous cells with fibroblastic features, more abundant and larger, the nearer they are to the basal membrane. In the segment of the marginal cells adjoining the endolymphatic cleft sometimes shows up a basal body, suggesting the existence of a kinocilium. The cellular surface is covered with small microvilli. In the 50 day old guinea pig fetus, the development of the stria vascularis is already similar to that of the adult animal.

Animals↗
PubMed1985

[Hormone-producing (paracrine) cells in the human labyrinth].

Presence of immunoreactive somatostatin in the covering epithelial cells of the spiral prominence was demonstrated by immunohistochemical methods. The concentration of somatostatin increases from the basal turn to the apical turn of the cochlea. Ultrastructural investigations of these cells reveal secretory granules with a diameter of 250-350 nm. The findings promote the existence of a local paracrine system of the inner ear.

Adolescent↗
PubMed1977

The peripheral hearing mechanism: new biophysical concepts for transduction of the acoustic signal to an electrochemical event.

A theory of peripheral function in hearing is proposed. It accounts for temporal discrimination among simultaneously received wave and pulse signals, cochlear analysis of acoustic input, and transduction of acoustic energy into biochemical energy by means of resonance and ion-shuttling involving the tectorial membrane and hair-cell complex. The postulated mechanism is such that it can accommodate the enormous range of intensity accessible to the mammalian ear. Synthesized by the theory are numerous empirical observations and experimental results reported by a broad gamut of disciplines but hitherto not unified. Additional support derives from the characteristics of an artificial "cochlea" and an electret (protein) microphone or "ion exchange microphone" with implications for enzyme conformational change.

Acoustic Stimulation↗
PubMed1987

The role of endolymphatic sac surgery in the management of secondary endolymphatic hydrops associated with perilymphatic fistulas: preliminary observations.

The evidence for the existence of secondary endolymphatic hydrops in patients with perilymphatic fistulas is reviewed and the indications for treatment of such hydrops in patients with fistulas are discussed. The indications for and results of combined fistula repair by middle ear exploration and endolymphatic sac surgery in fifteen patients are presented. The preliminary results in these patients appear encouraging. Patients with recurrent perilymphatic fistulas, or with symptoms of attacks of spinning vertigo after fistula repair, and those who present with severe imbalance with findings of a perilymphatic fistula appear to be candidates for combined fistula and sac surgery.

Adult↗
PubMed1985

An experimental study on the frog semicircular canal--functions of cupula and vestibular ganglion.

An isolated frog posterior semicircular canal was stimulated either by mechanical or thermal endolymphatic flow. Ampullofugal stimulation induced action potentials from the posterior ampullary nerve. These potentials adapted in six to eight seconds. While mechanical endolymphatic flow was induced, the cupula maintained its shift position without swinging back to the neutral point. This indicates that adaptation is mainly of sensorineural origin. When the canal was stimulated by a piece of frozen Ringer's solution, an increase in spike discharge was observed. The responses from the vestibular nerve trunk were compared to those from the posterior ampullary nerve. The time course of the response was shorter and the maximum spike count was smaller in the recordings from the vestibular nerve trunk.

Action Potentials↗
PubMed1985

Anatomy of the brainstem and the lower cranial nerves, vessels, and surrounding structures.

In this article some results of our investigations on the brainstem, the lower cranial nerves, and the nerve-vessel-relations in the posterior cranial fossa are reviewed. For comparison, the pertinent findings published by other authors are also included. Particular attention has been given to the topographic measurements of the canal systems in the petrous bone and the nerve-vessel-relations in the jugular fossa area.

Brain Stem↗
PubMedDate not supplied

[Electron microscopic study of the tegmentum vasculosum of the cochlear canal in chick embryos].

Ultrastructural studies have been made on the three types of cells composing the tegmentum vasculosum in the cochlea of chick embryos as well as on the growth of capillaries within the tegmentum. Inside the tegmentum, specific intercellular cavities were found filled with a fibrillar network. Temporal correlation is discussed between the development of the auditory function of the cochlea and differentiation of the tegmentum. Possible functional role of different cell types and of the described cavities is also discussed.

Animals↗
PubMed1985

Cochlear endolymphatic shunt for Meniere's disease.

We have now performed the cochlear endolymphatic shunt operation for Meniere's disease on 102 ears and have follow-up data on ninety cases. In this fourth report of results of the procedure, we show that after follow-up ranging from one month to six years (average 22.3 months), definitive vertigo was relieved in 72% of the cases and that hearing at the time of most recent audiogram (average 12.6 months postoperatively) was worse (AAO criteria) in 45% of the cases.

Adolescent↗