Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cochlear Duct”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources
PubMedDate not supplied

Ante mortem ruptures of the endolymphatic membranes in children: real finding or artifact?

We undertook this study to determine whether or not ante mortem ruptures of the endolymphatic membranes occurred naturally in the infantile labyrinth, what were the most frequent locations and to assess the statistical correlation of an earlier finding of bulging of Reissner's membrane in pediatric temporal bones. We examined 128 temporal bones from 80 children between the ages of newborn to 12 years with an average age of 15.4 months. All temporal bones were prepared by the celloidin technique and studied by light microscopy. The endolymphatic membranes of the cochlear duct, saccule, utricle and semicircular ducts were examined for ruptures. A rupture of the saccule and utricle was considered to be an ante mortem event if its edges were rolled and bound with fine adhesions and could be identified in adjacent sections. Ante mortem ruptures were seen in 11.1% of the specimens and occurred in 2.4% in Reissner's membrane, in 6.3% in the saccular membrane and in 2.4% in the utricular membrane. In these specimens, the histopathological changes included atrophy of the stria vascularis and collapse of the organ of Corti, which provided further evidence of an ante mortem event. Infants with extralabyrinthine congenital anomalies or children who were treated with chemotherapy were more likely to develop ruptures of the endolymphatic membranes if they also received aminoglycosides.

Artifacts↗
PubMed1975

Aspirin ototoxicity in the guinea pig.

Aspirin ototoxicity has been studied on guinea pigs by shiver-audiometry and histological investigation of the cochlear duct. One dose of 350 mg/kg has provoked, after 7 h, a mean hearing loss of 18-24 dB at 0.25-8 kHz, followed by complete recovery in 3 days. The difference between the administration of 50 mg/kg/day and 350 mg/kg/day consists of a wide extension of the frequencies involved, and in about 10 dB a greater hearing loss. In both cases, no appreciable recovery of hearing was observed after 22 days (the histological investigations were negative). The biochemical pathogenesis of aspirin ototoxicity is discussed and periodical audiometric controls before and during salicylate treatment are recommended.

Animals↗
PubMed1981

Cochleo-saccular degeneration in one of three sisters with hereditary deafness, absent gastric motility, small bowel diverticulitis and progressive sensory neuropathy.

This is a report of cochleo-saccular degeneration found in temporal bones from a patient who had suffered from slowly progressive and total sensorineural deafness which had an inherited origin. At age 8, this patient began to complain of hearing loss, and by age 10 she was totally deaf. The patient was 1 of 3 female siblings who have suffered from an exactly identical progressive disease: deafness, absent gastric motility, small bowel diverticulitis and ulceration, and sensory neuropathy. The temporal bone pathology found in this case was the degenerative change in the cochlear duct and sacculus. No pathology was found in the utriculus and semicircular canals.

Adolescent↗
PubMed1989

Change in K+ activity of the scala media produced by vasopressin.

The endocochlear potential (EP) and K+ activity in the scala media were recorded by means of K+-sensitive double-barreled microelectrodes in the second turn of the cochlea of the guinea pig during the perilymphatic perfusion with vasopressin. Vasopressin produced a decrease in K+ activity in the scala media following a decrease in EP. The decrease in K+ activity in the scala media relative to the EP reduction produced by vasopressin was not significantly different from that by perilymphatic perfusion with furosemide. The present results suggest that vasopressin changes the EP by acting on the stria vascularis.

Animals↗
PubMedDate not supplied

Effects of high-frequency sound on electrochemical potential using the single-barrel method in guinea pigs.

There are only a few studies investigating the effects of ultrasound on hearing. This paper reports on an experimental investigation on the effect of the long-time exposure to a moderate sound pressure level, high-frequency sound of 16 kHz on the guinea pig inner ear using electrophysiological methods. A decrease of the absolute value of negative potential was observed in the endocochlear potential (EP). The effects of high-frequency sound on EP and electrochemical potential could be explained by a change in the K+ permeability of hair cells.

Acoustic Stimulation↗
PubMed2001

Histopathology of cochlear implants in humans.

The insertion of an intrascalar electrode array during cochlear implantation causes immediate damage to the inner ear and may result in delayed onset of additional damage that may interfere with neuronal stimulation. To date, there have been reports on fewer than 50 temporal bone specimens from patients who had undergone implantation during life. The majority of these were single-channel implants, whereas the majority of implants inserted today are multichannel systems. This report presents the histopathologic findings in temporal bones from 8 individuals who in life had undergone multichannel cochlear implantation, with particular attention to the type and location of trauma and to long-term changes within the cochlea. The effect of these changes on spiral ganglion cell counts and the correlation between speech comprehension and spiral ganglion cell counts were calculated. In 4 of the 8 cases, the opposite, unimplanted ear was available for comparison. In 3 of the 4 cases, there was no significant difference between the spiral ganglion cell counts on the implanted and unimplanted sides. In addition, in this series of 8 cases, there was an apparent negative correlation between residual spiral ganglion cell count and hearing performance during life as measured by single-syllable word recognition. This finding suggests that abnormalities in the central auditory pathways are at least as important as spiral ganglion cell loss in limiting the performance of implant users.

Aged↗
PubMed2005

Fine structure histopathology of labyrinthitis ossificans in the gerbil model.

Labyrinthitis ossificans (LO) is the pathological deposition of new bone within the lumen of the cochlea and labyrinth. This process occurs most commonly as a result of infection or inflammation affecting the otic capsule. Trauma and vascular compromise can also lead to neo-ossification within the otic capsule. The mechanism that regulates this process remains unestablished. This study details the end-stage histopathology in high-resolution plastic thin sections. Twenty Mongolian gerbils were infected by intrathecal injection of Streptococcus pneumoniae type 3 followed by subcutaneous penicillin G procaine (8 days) and were painlessly sacrificed 3 months later. The cochleas were serially divided and sectioned for light and electron microscopy. Sixteen of 20 animals (27 of 40 cochleas) demonstrated LO. Cochlear damage was most extensive in the vestibule and basal turn and decreased toward the apex, which often appeared normal. The histopathologic findings consisted of 1) new bone, calcospherites, osteoid, and fibrosis without dense connective tissue or osteoblasts extending from the endosteal wall into the lumen of the vestibule and scala tympani; 2) areas of dense connective tissue and osteoid enclosed by epithelial cells conjoined with the organ of Corti, stria vascularis, spiral ligament, and vestibular (Reissner's) membrane; and 3) partial to complete loss of the organ of Corti, spiral ligament cell bodies, stria vascularis, and spiral ganglion cells. Osteoblastic activity was not demonstrated in end-stage ossification in LO in the gerbil model. Neo-ossification appears to occur by calcospherite deposition along collagen-like fibrils within osteoid. The destruction of the organ of Corti, spiral ganglion cells, stria vascularis, and cells of Reissner's membrane and the spiral ligament occurs even in the absence of ossification of the cochlear duct.

Animals↗
PubMedDate not supplied

Effects of removal of the statoacoustic ganglion complex upon the growing otocyst.

An experiment was designed to answer the question as to whether or not the neural elements of the statoacoustic ganglion complex have a trophic effect upon the histodifferentiation of the sensory structures of the embryonic mouse inner ear anlage as it develops in vitro. The embryonic inner ear anlage with associated otic mesenchyme and statoacoustic ganglion complex was excised from 11, 12, and 13-day CBA/C57 mouse embryos. The inner ear explants of each gestational age group were further divided into two groups: the first group "A" (with) statoacoustic ganglion was explanted to the organ culture system without further surgical intervention; the second group "B" (without) statoacoustic ganglion underwent further surgical manipulation during which their statoacoustic ganglion complexes were dissected away prior to explantation to in vitro. The explanted embryonic inner ears were allowed to develope in organ culture until the equivalent of gestation day 21 in vivo was reached for each group; then all cultures were fixed and histologically processed and stained by a nerve fiber stain, in combination with a stain for glucoprotein membranes. Each specimen was code labeled and scored for histodifferentiation of sensory structures. Light microscopic observations confirmed that in group "A" cultures, statoacoustic ganglion neurons and their nerve fibers were present in association with the developed sensory structures; neither ganglion cell neurons nor their nerve fibers were found to be present in the sensory structures that developed in the group "B" organ culture specimens. Quantification revealed no consistent trend of greater occurrence of any sensory structure in the groups of explants analyzed. The presence of such a trend would have signified the probable existence of a trophic effect of the statoacoustic ganglion neural elements upon development of inner ear sensory structures in the group "A" explants of the 11, 12, and 13-day embryo inner ear organ culture specimens when compared to the aganglionic group "B" cultures. Microscopic comparison of the sensory structures and their sensory hair cells that developed in the organ cultures revealed no differences in the quality of the histodifferentiation of eithergroup "A" or goup "B" explants. A base to apex pattern of histodifferentiation of the organ of Corti sensory structures, which has been described to occur in vivo, was noted to occur in the in vitro developed cochlear ducts of all of the explanted inner ears without respect to whether neural elements were present ("A") or absent ("B") during development. It was concluded from the quantification of histodifferentiation data and the above observation on the pattern of differentiation of Corti's organ that no trophic effect of neural elements of the statoacoustic ganglion complex influencing the histodifferentiation of sensory structures of 11, 12, and 13-gestation day mouse embryo inner ear explants as they differentiate in vitro could be demonstrated.

Animals↗
PubMedDate not supplied

Organ culture of the mammalian and avian embryo otocyst.

The use of a chemically defined medium supplemented with serum has proved most suitable for the growth of the isolated embryonic otocyst in vitro. Complete differentiation of the cochlear duct and of the vestibular apparatus ensued and is described. The system is reliable for organ cultures of both the avian and mammalian otocyst and for the study of various lesions affecting the inner ear and middle ear.

Animals↗
PubMedDate not supplied

Ear anomalies associated with renal dysplasia and immunodeficiency disease. A histopathological study.

The histopathologic study of the temporal bones of a case with low-set rudimentary auricles, without preauricular pits or cervical fistula is presented. Abnormalities of the middle and inner ear, fusion of the kidneys, hydrocephalus, short-limbed dwarfism and immunodeficiency are described. An abnormally low position of the middle cranial fossa in relation to the petrous pyramid was observed. The cochlea was of normal length. The modiolus was poorly developed with apparently normal population of ganglion cells and moderate diffuse hydrops of the cochlear duct and saccule. The stria vascularis was partially degenerated in the upper apical coil. Vestibular abnormalities included bilateral absence of common crus of the vertical canals and unusually high origin of endolymphatic aqueduct with no medial dilation present, the convoluted portion of the sac located beneath the dura.

Abnormalities, Multiple↗
PubMedDate not supplied

Temporal bone findings in hemifacial microsomia.

The temporal bone findings in a case of hemifacial microsomia are described with photographs. The right facial hypoplasia was associated with anophthalmia and microtia on the same side. The right petrous bone was hypoplastic and showed total superior dehiscence of the internal acoustic meatus. Th otic capsule was deformed with an underdeveloped cochlear modiolus grossly deficient in spiral ganglion population. The spiralling cochlear shell showed partial deficiency of the interscalar septum between the middle and apical coils. The cochlear duct was shorter than that on the normal side; the organ of Corti however was normal. The vestibular system did not show any structural abnormality except for the degeneration and reduction of the Scarpa's ganglion cells and nerve fibers. An additional interesting fact was that the facial nerve was totally absent in the temporal bone except for its nervus intermedius component.

Abnormalities, Multiple↗
PubMedDate not supplied

Cochlear fluid balance. A clinical/research overview.

Stria edema, and in some cases atrophy, follows osmotic agents, loop-inhibiting diuretics, acoustic trauma, and rupture of Reissner's membrane. All have in common an imbalance of fluid and electrolytes in the cochlear duct. The glycerol test causes temporary improvement in hearing in Menière's disease. Glycerol causes stria edema and collapse of Reissner's membrane in the chinchilla. Stria edema, as well as stria atrophy, are found in Menière's disease. Metabolic manipulation of the stria might be that the best approach in the search for successful treatment of Menière's disease.

Adenylyl Cyclase Inhibitors↗
PubMed1991

Transport of 5-hydroxydopamine and horseradish peroxidase through the perilymph-endolymph barrier.

The distribution of 5-hydroxydopamine (5-OHDA) and horseradish peroxidase (HRP) in the cochlea was examined by light and electron microscopy after perilymphatic perfusion. Reaction product of 5-OHDA was observed along the endolymphatic surface of the cochlear duct in both 10-minute and 30-minute perfusions, while that of HRP was observed only in the 30-minute perfusion. Both tracers were found in pinocytotic vesicles of Reissner's membrane, Claudius' cells, and Hensen's cells. No labeling was seen in tight junctions of the epithelial cells lining the scala media. The epithelial cells of the spiral prominence showed various degrees of degeneration in the 5-OHDA experiment. These morphologic findings suggest that 5-OHDA and HRP can enter the endolymphatic space from the perilymphatic space by pinocytosis and that the degree of transport depends on the size of the particles.

Animals↗
PubMed1997

Horseradish peroxidase permeation from the capillaries of the stria vascularis after inoculation of endotoxin into the middle ear.

Escherichia coli-derived endotoxin was inoculated in the middle ear of guinea pigs 24 hours after being injected intraperitoneally. Twenty-four hours after the middle ear inoculation, horseradish peroxidase (HRP) was injected via the femoral vein and the permeability of HRP through the capillaries of the stria vascularis and the destination of the leaked HRP were examined. A large amount of HRP leaked out of the capillary through he opened endothelial cell junctions and penetrated the enlarged intercellular spaces. Leaked HRP entered the pinocytotic vesicles of the intermediate cells. Even slightly degenerated intermediate cells retained this function. The HRP penetrated the spongelike structure of the marginal cells leading to the intercellular space. This structure was not observed without endotoxin. The HRP could not pass the cochlear duct through the tight junctions between marginal cells. Blood sludging was observed in the strial capillaries. It appeared more frequently in the upper three turns than in the basal turn. The HRP leakage out of the capillaries was observed not only in the upper three turns but also in the basal turn.

Animals↗
PubMedDate not supplied

Cochlear nerve projections following organ of corti destruction.

Experimental organ of Corti destruction results in (1) secondary loss of all type I spiral ganglion neurons, (2) development of type III spiral ganglion neurons, (3) degeneration of most cochlear nerve myelinated fibers, and (4) terminal degeneration in the ventral and dorsal cochlear nuclei. The first signs of degenerative changes occur by eight days after organ of Corti destruction and degeneration debris remains until 28 weeks after destruction.

Animals↗
PubMedDate not supplied

Evidence for intracochlear impedance changes following ethacrynic acid administration.

The effects of intra-arterial 30-, 40-, and 50-mg/kg doses of ethacrynic acid upon cochlear function in guinea pigs were studied for periods of three to five hours. Cochlear potentials recorded in the first turn included the endocochlear potential, whole nerve response, cochlear microphonics, and summating potentials in scala media, scala tympani, and scala vestibuli. Evidence of organ of Corti damage at 50 mg/kg was found in addition to electrical impedance changes in the cochlear membranes at all dose levels.

Animals↗