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Results for “Endolymphatic Duct”

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At least 19 recordsLinked to original sources

PubMed1997

[The vascular pattern of the endolymphatic duct, endolymphatic sac and its anatomic differences in guinea pigs].

In order to study the vascular pattern of the endolymphatic duct and sac, endolymphatic duct and sac were examined with vascular Indian ink injection and image analysis. The Results were as follows: 1. In the 20 temporal bones, 17 (85%) had posterior meningeal artery (PMA) and posterior vestibular artery (PVA) supply and the rest (3 specimens, 15%) had no PVA supply; 2. The distribution frequency of PMA in the endolymphatic sac was much higher than that of PVA(P < 0.01), but the distribution of PMA and PVA in the endolympatic duct were not different (P > 0.05). The conclusions is that there are anatomic differences in vascular supply and pattern of the endolymphatic duct and sac, PMA is the main vascular structure in the endolymphatic sac.

Animals↗

PubMed2000

MR imaging of the enlarged endolymphatic duct and sac syndrome by use of a 3D fast asymmetric spin-echo sequence: volume and signal-intensity measurement of the endolymphatic duct and sac and area measurement of the cochlear modiolus.

BACKGROUND AND PURPOSE: In enlarged endolymphatic duct (EED) and sac (EES) syndrome, deformity of the EED and EES is congenital; however, hearing loss is acquired. To investigate the pathophysiology of progressive sensorineural hearing loss in EED and EES syndrome, we measured the volume of the EED and EES, the diameter of the EED and EES, the area of the cochlear modiolus, and the signal intensity of the EES and compared our findings against degree of hearing loss. METHODS: Thin-section MR images of 33 ears in 17 patients with EED and EES syndrome were studied. All studies were obtained on a 1.5-T MR unit using a quadrature surface phased-array coil. Heavily T2-weighted 3D fast asymmetric spin-echo images were obtained with a voxel size of 0.3 x 0.3 x 0.8 mm without zero-fill interpolation. Two radiologists traced the areas of the EED and EES manually, and the volume was calculated. The area of the cochlear modiolus, diameter of the EED and EES, and signal intensity of the EES were also measured by drawing regions of interest manually. The signal intensity ratio of EES/CSF was calculated. These measured values were compared against audiographic data, and the degree of linear correlation was determined. RESULTS: The volume of the EED and EES, the area of the modiolus, the diameter of the EED and EES, and the signal intensity of the EES did not show significant correlation with degree of hearing loss. CONCLUSION: These findings suggest that there is a microscopic area of damage or fragility in the inner ear not visible even with thin-section heavily T2-weighted MR imaging.

Adolescent↗

PubMed2003

Network organization of interstitial connective tissue cells in the human endolymphatic duct.

The human endolymphatic duct (ED) and sac of the inner ear have been suggested to control endolymph volume and pressure. However, the physiological mechanisms for these processes remain obscure. We investigated the organization of the periductal interstitial connective tissue cells and extracellular matrix (ECM) in four freshly fixed human EDs by transmission electron microscopy and by immunohistochemistry. The unique surgical material allowed a greatly improved structural and epitopic preservation of tissue. Periductal connective tissue cells formed frequent intercellular contacts and focally occurring electron-dense contacts to ECM structures, creating a complex tissue network. The connective tissue cells also formed contacts with the basal lamina of the ED epithelium and the bone matrix, connecting the ED with the surrounding bone of the vestibular aqueduct. The interstitial connective tissue cells were non-endothelial and non-smooth muscle fibroblastoid cells. We suggest that the ED tissue network forms a functional mechanical entity that takes part in the control of inner ear fluid pressure and endolymph resorption.

Connective Tissue Cells↗

PubMed2006

An interstitial network of podoplanin-expressing cells in the human endolymphatic duct.

The human endolymphatic duct (ED) with encompassing interstitial connective tissue (CT) is believed to be important for endolymph resorption and fluid pressure regulation of the inner ear. The periductal CT cells are interconnected via numerous cellular extensions, but do not form vessel structures. Here we report that the periductal CT is populated by two distinct cell phenotypes; one expressing podoplanin, a protein otherwise found on lymph endothelia and on epithelia involved in fluid fluxes, and a second expressing a fibroblast marker. A majority of the interstitial cells expressed podoplanin but not the lymphatic endothelial cell markers hyaluronan receptor (LYVE-1) or vascular endothelial growth factor receptor-3 (VEGFR-3). The fibroblast marker positive cells were found close to the ED epithelium. In the mid- and distal parts of the ED, these cells were enriched under folded epithelia. Furthermore, subepithelial CT cells were found to express activated platelet derived growth factor (PDGF)-beta receptors. Cultured CT cells from human inner ear periductal and perisaccular explant tissues were identified as fibroblasts. These cells compacted a three-dimensional collagen lattice by a process that could be promoted by PDGF-BB, a factor involved in interstitial fluid pressure regulation. Our results are compatible with the notion that the periductal CT cells are involved in the regulation of inner ear fluid pressure. By active compaction of the periductal CT and by the formation of villous structures, the CT cells could modulate fluid fluxes over the ED epithelium as well as the longitudinal flow of endolymph in the ED.

Biomarkers↗

PubMed1991

Embryology of the human endolymphatic duct and sac.

Endolymphatic sac specimens from human embryos, ranging in age from 8 to 20 weeks, were examined in order to get a good understanding of the embryological development. The gross development can be separated into three phases, with the first phase terminating around week 10, the second phase between weeks 11 and 15-16 and the third phase lasting to week 20. While presenting as an immature oval appendage emanating from the vestibule in the first phase, the sac then develops into its more mature shape with crypts and folds within the epithelial lining. The third period is characterized by splitting up of the lumen into separate tubules. The epithelial cells differentiate particularly during the second and third phases with light- and dark-staining cells as well as granulated cells. It is evident that the development of the endolymphatic sac is not finished by week 20, even though it has attained many of its adult characteristics.

Endolymphatic Duct↗

PubMed1992

A technique to obtain and process surgical specimens of the human vestibular aqueduct for histopathological studies of the endolymphatic duct and sac.

The endolymphatic sac (ES) may play a crucial role in the pathophysiology of Ménière's disease. This paper presents a technique to obtain and process fresh human specimens of the endolymphatic duct (ED) and the presumably more active intraosseous portion of the ES obtained at surgery. The specimens are preserved with an intact bony shell around the ED and the intraosseous ES. This allows ultrastructural histopathological evaluation of the intraluminal contents, the epithelium and the subepithelial tissue as well as the mutual relationships of these structures. Various factors influencing ES ultrastructure are discussed. The results obtained from this method may increase our understanding of the possible role of the ES in the etiology of different inner ear disorders.

Endolymphatic Duct↗

PubMed1984

The ultrastructure of the human endolymphatic duct.

The fine structure of the human endolymphatic duct as observed at transmission electron microscopy (TEM) is described. After fixation of inner ears by perilymphatic perfusion adequately preserved tissue specimens were obtained. Our morphological findings seem to be in accordance with the earlier proposition that the human endolymphatic duct may be involved in endolymph resorption. The duct was found to contain otoconia-like bodies, suggesting that the endolymphatic duct and sac, may play a role in the turnover of macular otoconia.

Adult↗

PubMed1993

Arterial supply of the human endolymphatic duct and sac.

The arterial anatomy of the endolymphatic duct and sac was studied in vascular casts of methyl methacrylate of six human heads. The chief source of arterial blood supply to the endolymphatic duct and sac appeared to be the occipital artery. Arterioles entered the bone of the mastoid process. Arterioles in bone, the walls of the sigmoid sinus, and the posterior fossa dura coursed medially to supply the endolymphatic sac. The orientation of arterioles tended to be along the long axis of the endolymphatic duct and sac, whereas venules were more likely to be circumferentially oriented. Arterioles arising from dural vessels divided into deeper branches, which supplied periductal connective tissue, and superficial branches, which entered canaliculi of the vestibular aqueduct. Gross anatomic findings were confirmed by histologic examination of temporal bones.

Arteries↗

PubMed1994

Ultrastructure of the epithelial cells of the endolymphatic duct in the rat.

The ultrastructure of the epithelial cells of the endolymphatic duct in the rat is described, following vascular perfusion-fixation of live, anaesthetised and artificially respirated animals. The animals were fixed by means of a pressure feed-back controlled peristaltic pump and an isotonic perfusate-fixative containing glutaraldehyde and Dextran. The endolymphatic duct was isolated by microdissection after the perfusion-fixation, to omit the step of a demineralization procedure. The proximal, intermediate and juxta-saccular parts of the endolymphatic duct were embedded, sectioned and studied separately in the electron microscope. Postfixation in a solution containing OsO4 and potassium ferricyanide revealed a well-developed tubulo-cisternal endoplasmic reticulum (TER), not previously described. Serial sectioning and computerized three-dimensional reconstruction demonstrated a continuity of the TER through the cell from subsurface cisterns abutting on the apical cell membrane to subsurface cisterns abutting on the basolateral cell membrane. The TER resembles that found in solute transporting epithelia, e.g., renal proximal tubule, gall bladder, small intestine and choroid plexus. A fluid resorptive capacity of the epithelial cells of the endolymphatic duct is compatible with the fine structure revealed in the present study. Epithelial cells in the juxta-saccular part of the duct display morphological indications of a secretory activity; furthermore, multivesicular bodies were observed in the epithelial cells throughout the endolymphatic duct.

Animals↗

PubMed1995

Effects of endolymphatic duct occlusion on the structure and function of the endolymphatic sac in the adult guinea pig.

The endolymphatic sac (ELS) has been shown to respond rapidly to sudden disruptions in fluid balance such as labyrinthectomy or systemic administration of hyperosmolar agents. The present study was designed to determine the ELS response to slower changes in fluid dynamics by occluding the endolymphatic duct (ELD), thereby interrupting the longitudinal flow of endolymph to the ELS. Morphologic studies and autoradiographic techniques were used to evaluate the effects of ELD obstruction on the structure and function of the ELS after 48 hours. There were no significant changes in cellular morphology and a slight decrease in the incorporation of radiolabeled glucose when compared with normal ELS cells. We conclude that it is rapid change in fluid balance that triggers the ELS response, which is not seen with disruption of longitudinal flow.

Animals↗

PubMedDate not supplied

Endolymphatic duct and sac in patients with Meniere's disease. A temporal bone histopathological study.

The endolymphatic ducts and sacs of 25 temporal bones with idiopathic endolymphatic hydrops from individuals with Meniere's disease were studied and compared with the same number of control bones without endolymphatic hydrops from individuals with no premortem history of otologic disease. The control bones were selected so that the sizes of their vestibular aqueducts matched those temporal bones from individuals with Meniere's disease. The endolymphatic ducts and sacs of all bones were studied by the medial view graphic reconstruction method and/or histological observation under a light microscope. In the endolymphatic duct and sac of many of the temporal bones from patients with Meniere's disease were noted a diminution of the width of the endolymphatic duct in its isthmus portion, an increase in the area of the collapsed lumen of the endolymphatic sac, fibrotic changes in the perisaccular loose connective tissue, and an increase in the quantity of intraluminal eosinophilic material. The frequencies with which these pathological findings were noted in bones from individuals with Meniere's disease and in control bones were statistically significantly different. No significant differences were observed under light microscopic study between these two groups with regard to the condition of the epithelial cells, the degree of rugosity of the endolymphatic sac, or the appearance of melanin-like pigmentation of hyalinization in the perisaccular connective tissue.

Adult↗

PubMed1992

Periductal vessels of the endolymphatic duct.

Light microscope was used to examine the rich vascular plexus surrounding the human endolymphatic duct, both in the periductal loose connective tissue and in the bony channels surrounding the bony vestibular aqueduct. We also performed computer-aided three-dimensional reconstruction on one serially sectioned region of the endolymphatic duct. We found an anastomotic and looping network of vessels residing in the loose connective tissue close to the epithelium of the endolymphatic duct. This network often received a vascular contribution from the vessels in the periaqueductal bony channels. These findings were verified by light microscopic examination of 50 temporal bone specimens. Concurrent with this finding, histologic examination also showed different characteristic features of the vascular system of the endolymphatic duct-proximal sac areas and of the more distal parts of the endolymphatic sac. These features include the arrangement, quantity, and contents of the periaqueductal bony channels, as well as the organization of the bone containing these periductal bony channels. Findings from this study help the understanding of the anatomy of the human endolymphatic duct. In addition, they support and supplement earlier observations of the structure of the endolymphatic duct. We suggest the possible existence of a periductal vasculature system, similar in pattern to that in the endolymphatic sac, but specialized to work with the duct to aid its function.

Connective Tissue↗

PubMed1997

MR of the endolymphatic duct and sac: findings in Menière disease.

PURPOSE: To compare the visibility of the endolymphatic duct and sac on high-resolution MR images with the symptoms and clinical course in patients with Menière disease. METHODS: Twenty-two patients with unilateral Menière disease were sorted into two groups on the basis of the clinical stage of their disease at the time of imaging. Group 1 included patients in the acute phase, who presented with vertigo. Group 2 comprised patients in the nonacute phase of the disease, who were studied 9 days or more after an episode of vertigo. RESULTS: During acute attacks, the endolymphatic duct and sac were not adequately visible in the affected ear but were visible in the unaffected ear. During remission, the endolymphatic duct and sac were not observed in clinically advanced patients, but they were seen in patients in the early and intermediate stages. CONCLUSION: High-resolution MR imaging can be used to evaluate the endolymphatic duct and sac: visible abnormalities and lack of a visible endolymphatic duct and sac correlate with the clinical course of Menière disease.

Acute Disease↗

PubMed1992

Experimental interruption of the endolymphatic duct and its effect on the DC potential in the endolymphatic sac.

The endolymphatic sac (ES) of the guinea pig was isolated from the remainder of the inner ear by means of surgical interruption of the endolymphatic duct (ED). The DC potential in the ES lumen and the morphology of the ES were studied using glass micro-electrodes and a light microscope at various time intervals after the interruption of ED. The DC potential did not significantly change 1 h postoperatively, compared to findings in the non-operated ear, but a significant decrease of the DC potential was observed after 1, 3 and 7 days postoperatively. A histologically-stainable substance in the ES lumen was enhanced on the operated side. The isolated ES shows a disturbance of mechanism(s) maintaining the DC potential and there is a secretion of a stainable substance into its lumen.

Animals↗

PubMed1995

The endolymphatic duct and sac of the rat: a histological, ultrastructural, and immunocytochemical investigation.

A study of the ultrastructure, vascularization, and innervation of the endolymphatic duct and sac of the rat has been performed by means of light- and electron-microscopic and immunocytochemical methods. Two different types of epithelial cells have been identified: the ribosome-rich cell and the mitochondria-rich cell. These two cell types make up the epithelium of the complete endolymphatic duct and sac, although differences in their quantitative distribution exist. The morphology of the ribosome-rich cells varies between the different parts of the endolymphatic duct and sac; the morphology of the mitochondria-rich cells remains constant. According to the epithelial composition, vascularization, and structural organization of the lamina propria, both duct and sac are subdivided into three different parts. A graphic reconstruction of the vascular network supplying the endolymphatic duct and sac shows that the vascular pattern varies among the different parts. In addition, the capillaries of the duct are of the continuous types, whereas those supplying the sac are of the fenestrated type. Nerve fibers do not occur within the epithelium of the endolymphatic duct and sac. A few nerve fibers regularly occur in the subepithelial compartment close to the blood vessels; these fibers have been demonstrated in whole-mount preparations by the application of the neuronal marker protein gene product 9.5. Single beaded fibers immunoreactive to substance P and calcitonin-gene related peptide are observed within the same compartment. Dopamine-beta-hydroxylase-immunoreactive axons are restricted to the walls of arterioles. Morphological differences between the different portions of the endolymphatic duct and sac are discussed with regard to possible roles in fluid absorption and immunocompetence.

Animals↗

PubMed1984

Human endolymphatic duct. An ultrastructural study.

The fine structure of the human endolymphatic duct was observed by transmission electron microscopy. Well-preserved specimens were obtained after fixation of inner ear tissue by perilymphatic perfusion. The morphologic findings seemed to be in accordance with earlier propositions that the human endolymphatic duct may be involved in endolymph resorption. The duct was found to contain otoconialike bodies, suggesting that the endolymphatic duct and sac in man may also play a role in the turnover of macular otoconia.

Adult↗

PubMed2005

Imaging and clinical findings in large endolymphatic duct and sac syndrome.

OBJECTIVE: Large endolymphatic duct and sac syndrome (LEDS) is known as the most common kind of inner ear malformations, which is radiologically detectable. Nevertheless, nowadays many questions are not fully cleared and LEDS is relatively unknown among general radiologists. The aim of this study was to evaluate the incidence of LEDS in the own patient population and to present our experiences regarding imaging findings, clinical presentation and follow up. MATERIALS AND METHODS: Based on a complete recording of all patients, sent from ENT department to radiology, we identified all radiological diagnosed cases of inner ear malformations including LEDS and all patients in whom an inner ear malformation was clinically suspected. The retrospective study included clinical records, HR-CT and MRI performed between 1994 and 2002. RESULTS: Among 169 patients (338 ear), 17 of patients (median age: 12 years) and 28 ears, respectively, had enlarged endolymphatic structures. In 10 patients - 6% - (15 ears), no other abnormalities were detected, called isolated LEDS, seven patients showed additional inner ear abnormalities. One patient showed a labyrinthine hemorrhage after sudden hearing loss. Audiometric data revealed sensorineural hearing loss in 22 ears, deafness in 5 ears and normal hearing in 1 case of 28 ears. In 10 (67%) of 15 ears with isolated LEDS, the hearing loss was downward-fluctuating progressive. Twelve patients (eight with isolated LEDS) had partly repeated sudden hearing losses. A trigger for worsening of hearing was found in five patients. A correlation between the severity of morphological changes on imaging and the degree of hearing disturbances could not be detected. Only four young patients underwent a radiological examination within the first or second year after onset of hearing loss. Three patients received a cochlear implant. CONCLUSIONS: LEDS might be the cause of progressive hearing loss and repeated acute hearing losses in children and young adults. Imaging plays an important role in making the diagnosis.

Adolescent↗

PubMed1992

Microorganism transport in the human endolymphatic duct.

There are indications that endolymphatic sac (ES) may be an immunologically active part of the inner ear. So far, no microorganisms or foreign substances have been localized in this area under 'normal' conditions. Only a limited number of human specimens, including the entire endolymphatic duct (ED) and ES, have been collected and analyzed from cadavers or surgical biopsy specimens. In this study, 6 human ED and ES collected from cadavers and at surgery were analyzed by light and electron microscopy. This was done in order to investigate if microorganisms may normally be drained at this route into the ES. Some microorganisms (Mycoplasma pneumoniae) were found in the lumen and subepithelial tissue of 1 human ED. These observations suggest that microorganisms may also be locally processed and disposed at the level of the ED. These results add further evidence as to the immunodefensive role of the human ES.

Endolymphatic Duct↗