Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Tectorial Membrane”

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 37 records · Page 2Linked to original sources
PubMed1992

The protein composition of the avian tectorial membrane.

Gel electrophoretic analysis of the avian tectorial membrane under non-reducing conditions reveals the presence of 2 major proteins with apparent molecular masses of 195 and 41 kDa on 8.25% gels. Under reducing conditions, 6 polypeptides with apparent molecular masses of 146, 60, 56, 43, 35 and 31 kDa are consistently observed. None of these six polypeptides observed under reducing conditions are sensitive to digestion with collagenase, and all, except for the 43 kDa component, are degraded by treatment with cold acidic pepsin. The 60, 56 and 43 kDa polypeptides bind the peroxidase conjugated lectins from Canavalia ensiformis and Triticum vulgaris, indicating the presence of mannose, N-acetyl glucosamine and/or sialic acid. The 146, 60 and 56 kDa bands undergo a shift in electrophoretic mobility after treatment of native tectorial membranes with the enzyme neuroaminidase. Fibronectin and Type II collagen cannot be detected in the avian tectorial membrane by either immunoblotting or immunofluorescence techniques. Polyclonal antisera raised against the different polypeptides after partial purification by one dimensional gel electrophoresis confirm that these proteins are all components of the tectorial membrane, and show that they are restricted to the otolithic and tectorial membranes within the inner ear. Analysis of a wide variety of other tissue types indicates that the 60, 43 and 35 kDa components can only be detected within the inner ear, and that the antisera recognising the 146 and 31 kDa components only show cross-reactivity within the head, with the anti-146 kDa antibodies staining the mucus ducts supplying the olfactory epithelium and the anti-31 kDa antibodies staining granular elements in the cells of the respiratory epithelium. The results suggest that certain of the tectorial membrane components may be novel matrix molecules unique to the inner ear, and that some of the other proteins may be antigenically related to mucins.

Animals↗
PubMed2007

The tectorial membrane: anatomical, biomechanical, and histological analysis.

There is minimal information in the literature regarding the tectorial membrane. Further, information in the literature regarding the anatomy and function of this structure is often contradictory. We performed the current study to elucidate further this structure's detailed anatomy, function, and histology. Thirteen adult cadavers underwent dissection of their tectorial membranes and detailed observations and measurements were made of them. Ranges of motion of the craniocervical junction were performed before and after transection of this structure. Histological analysis was performed on all membranes. The tectorial membrane was found to attach much more superiorly than previously described and was found to be firmly adherent to the cranial base and body of the axis but not to the posterior aspect of the odontoid process. The mean thickness of this membrane was found to be 1 mm. Flexion of the head made the tectorial membrane fully taut at 15 degrees and extension made it fully taut at 20 degrees; however, there was a buckling effect (redundant tectorial membrane) noted at the level of the odontoid process in extension. With the alar and transverse ligaments cut and with flexion of the head, the middle portion of this membrane was stretched over the odontoid process, thus acting as a "hammock" that inhibited the odontoid process from moving posteriorly. The tectorial membrane did not limit cervical flexion per se but rather helped to insure that the odontoid process did not impinge into the cervical canal. Lateral flexion was not found to be limited by this structure. Histologically, parallel collagen fibers with spindle-shaped fibrocytes were observed within this membrane and near its attachment to the posterior axis, the collagen fibers were noted to be more homogenous with larger non-spindled fibrocytes. At the cranial attachment of the tectorial membrane, multiple calcified areas were noted that interdigitated with the underlying bone. Also near this cephalic bony attachment, there was an increase in the number of elastic fibers, which were found running parallel with the surrounding Type III collagen fibers. The tectorial membrane was found to attach much more superiorly than previously described. We would propose that the tectorial membrane provides for a second line of defense, preventing the odontoid process from compressing the spinal cord and by doing so, secondarily limits movement of the craniocervical juncture. This hypothesis is strengthened by the finding of many elastic fibers in the tectorial membrane. To our knowledge, our study is the first to perform a detailed histological analysis of the tectorial membrane. We hope that these data are useful to the clinician who investigates this ligament of the craniocervical region.

Aged↗
PubMedDate not supplied

Structure of the avian tectorial membrane.

The avian tectorial membrane is a thick massive-appearing structure permeated by cavities, which probably facilitate the diffusion of endolymph. As revealed by scanning and transmission electron microscopy, the cavities are arranged in a characteristic honeycomb-like pattern and each hair bundle is enclosed in an alveolus. The open ends of the alveoli show the impressions of sensory hairs on one side. The rims about the cavities are attached to the microvilli of the supporting cells by means of fibrous material. These morphological aspects are compared with those reptiles and mammals, and the functional significance of the fibrillar anchors is discussed.

Animals↗
PubMed1999

A micromechanical model of the cochlea with radial movement of the tectorial membrane.

The function of the tectorial membrane in the cochlear micromechanics is uncertain. In modeling approaches some models have assumed it to be a resonator that participates in the sharp tuning mechanisms of the cochlea with its mass coupled to the ciliary stiffness of outer hair cells, being driven by the shear force between the reticular lamina and itself. This paper presents a different type of micromechanical model which assumes that the tectorial membrane is driven by a lymphatic fluid flow that can be shown to have a substantial radial component. It also assumes that the reticular lamina is relatively stiff and thereby restrains the top end of outer hair cells that exert a force to the basilar membrane via Deiters cells. When combined with a three-dimensional block model, it can simulate the sharp tuning mechanisms of the cochlea well.

Acoustic Stimulation↗
PubMed1996

Resonant tectorial membrane motion in the inner ear: its crucial role in frequency tuning.

The tectorial membrane has long been postulated as playing a role in the exquisite sensitivity of the cochlea. In particular, it has been proposed that the tectorial membrane provides a second resonant system, in addition to that of the basilar membrane, which contributes to the amplification of the motion of the cochlear partition. Until now, technical difficulties had prevented vibration measurements of the tectorial membrane and, therefore, precluded direct evidence of a mechanical resonance. In the study reported here, the vibration of the tectorial membrane was measured in two orthogonal directions by using a novel method of combining laser interferometry with a photodiode technique. It is shown experimentally that the motion of the tectorial membrane is resonant at a frequency of 0.5 octave (oct) below the resonant frequency of the basilar membrane and polarized parallel to the reticular lamina. It is concluded that the resonant motion of the tectorial membrane is due to a parallel resonance between the mass of the tectorial membrane and the compliance of the stereocilia of the outer hair cells. Moreover, in combination with the contractile force of outer hair cells, it is proposed that inertial motion of the tectorial membrane provides the necessary conditions to allow positive feedback of mechanical energy into the cochlear partition, thereby amplifying and tuning the cochlear response.

Animals↗
PubMed1987

Regeneration of the tectorial membrane in the chick cochlea following severe acoustic trauma.

Damage to the tectorial membrane caused by acoustic trauma was examined with scanning and transmission electron microscopy immediately after exposure and at selected time points over a 10 day recovery period. At 0 h of recovery the structure of the tectorial membrane overlying the region of hair cell damage was severely disrupted and connections between the membrane and the basilar papilla were lost. By 24 h of recovery, regeneration of the tectorial membrane was evident in the secretion of new matrix materials by the supporting cells of the basilar papilla. By 10 days of recovery a new honeycomb-like matrix had replaced the segment of damaged tectorial membrane, re-established connections with hair cell stereocilia and become fused with adjacent regions of undamaged tectorial membrane. However, the regenerated segment included only the honeycomb-like structure of the lower layer of the normal tectorial membrane. The laterally-oriented fibers which form the upper layer of the membrane were not regenerated over the damaged region. These findings indicate that the tectorial membrane is regenerated in parallel with the hair cells during recovery from acoustic trauma but the full extent of this recovery and its effect on cochlear function are not yet clear.

Animals↗
PubMed1993

Uronic acid-containing glycosaminoglycans and keratan sulfate are present in the tectorial membrane of the inner ear: functional implications.

The tectorial membrane is a gel-like, acellular connective tissue overlying the microscopic organ of Corti--the auditory sensory structure. It is instrumental in the sound-synchronous deflection of the stereocilia of the hair cells, a central event in auditory transduction. It is well established that collagen, primarily type II, constitutes the major protein of the tectorial membrane, with smaller amounts of types IX and XI also present. However, conclusive information on the proteoglycans in this structure is lacking. Tectorial membranes were extracted with a 4 M guanidine--HCl solvent, and proteoglycans isolated after ethanol precipitation and collagenase treatment. A colorimetric assay based on the binding of the cationic dye safranin O to glycosaminoglycans, in combination with enzymatic techniques, detected significant amounts of chondroitin sulfate and keratan sulfate (0.29 and 0.17% on a wet weight basis, respectively). Agarose-polyacrylamide electrophoresis of chondroitinase-digested samples revealed a core protein with a similar molecular mass to that of the large cartilage proteoglycan aggrecan. This proteoglycan reacted with the antibody 3-B-3 (recognizing modified chondroitin 6-sulfate linkage region oligosaccharides). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed several low molecular mass proteins which reacted with 5-D-4, specific for keratan sulfate, one of which showed characteristics of fibromodulin. Comparison of the quantitative aspects of various connective tissue components of tectorial membrane with other type II collagen-containing structures revealed that this tissue resembles highly hydrated cartilage.

Animals↗
PubMed2003

Static material properties of the tectorial membrane: a summary.

The tectorial membrane (TM) is a polyelectrolyte gel. Hence, its chemical, electrical, mechanical, and osmotic properties are inextricably linked. We review, integrate, and interpret recent findings on these properties in isolated TM preparations. The dimensions of the TM in alligator lizard, chick, and mouse are sensitive to bath ion concentrations of constituents normally present in the cochlear fluids - an increase in calcium concentration shrinks the TM, and an increase in sodium concentration swells the TM in a manner that depends competitively on the calcium concentration. The sodium-induced swelling is specific; it does not occur with other alkali metal cations. We interpret these findings as due to competitive binding of sodium and calcium to TM macromolecules which causes a change in their conformation that leads to a change in mechanical properties. In mouse TM, decreasing the bath pH below 6 or increasing it above 7 results in swelling of the TM. Electric potential measurements are consistent with the notion that the swelling is caused by a pH-driven increase in positive fixed charge at low pH and an increase in the magnitude of the negative fixed charge at high pH which is consistent with the known protonation pattern of TM macromolecules. Increasing the osmotic pressure of the bathing solution with polyethylene glycol shrinks the TM and decreasing the ionic strength of the bathing solution swells the TM. Both results are qualitatively consistent with predictions of a polyelectrolyte gel model of the TM.

Animals↗
PubMed1992

Video-enhanced DIC images of the noise-damaged and regenerated chick tectorial membrane.

Exposure of the chick cochlea to acoustic overstimulation results in a loss of hair cells and a disruption of the tectorial membrane. With time, new hair cells are produced to replace those that are lost and, concurrently, a new tectorial membrane is regenerated. Previous studies of tectorial membrane regeneration examined tissues that were fixed and processed for scanning and transmission electron microscopy. This processing results in a considerable shrinkage of the membrane, and, therefore, it was unclear how the noise damage and subsequent regeneration affected the unfixed, in situ structure of the tectorial membrane. We have recently developed techniques for studying the unfixed tectorial membrane with video-enhanced differential-interference-contrast (DIC) light microscopy. Exposure to a 1500-Hz pure tone at 120 dB SPL for 24 h causes localized damage to the hair cells and tectorial membrane in the mid-proximal region of the basilar papilla. Examination of the unfixed membrane immediately after noise exposure shows that the damage to the tectorial membrane is actually caused by the acoustic trauma and is not an artifact of fixation. After 14 days of recovery, a thick, honeycomb of new matrix has grown from the supporting cells in the basilar papilla and has formed new connections with the stereocilia of surviving and regenerating hair cells. Moreover, this new honeycomb has fused with the remainder of the surrounding, undamaged tectorial membrane, thus reestablishing a continuity in the structure of the membrane across both the damaged and undamaged regions of the basilar papilla.

Acoustic Stimulation↗
PubMed1988

Tectorial membrane. I: Static mechanical properties in vivo.

Although the tectorial membrane in the mammalian cochlea plays a crucial role in hair-cell stimulation, its mechanical properties have never been investigated under conditions approximating those under which it normally functions. For this reason, we performed such investigations in live Mongolian gerbils. Access to the tectorial membrane was gained through the lateral wall in the second cochlear turn. As far as possible, sodium ions were kept away from the tectorial membrane by avoiding injury to Reissner's membrane, relieving the perilymphatic pressure, and rinsing the scala media with an isotonic KCl solution. The tectorial membrane was manipulated with a flexible micropipette in three, approximately orthogonal, directions. Under these conditions the membrane was found to be highly compliant and resilient, and to have a relatively high tensile strength. Its viscosity was low. Some of these attributes were altered by sodium ions, dyes, or death.

Animals↗
PubMed2005

Tectorial membrane injuries in children.

We report three cases of tectorial membrane injury in children. An increased interspinous ratio was identified on cervical spine radiographs. The tectorial membrane injuries were diagnosed by magnetic resonance imaging. The three children were restrained passengers in high-speed motor vehicle accidents, and all sustained polytrauma. Two children with partial tears of the tectorial membrane were immobilized in a halo, and one with a longitudinal tear of the tectorial membrane had an occiput-to-C2 fusion.

Accidents, Traffic↗
PubMed1983

Donnan equilibrium in the tectorial membrane.

Basic properties of the isolated tectorial membrane were investigated. Pieces of the membrane were equilibrated in various bathing fluids and the potential difference between the matrix of the membrane and the bathing fluid was measured, using micropipette electrodes. A negative potential was recorded within the membrane, and the magnitude of the potential was dependent upon the pH and ionic strength of the bathing fluid. These observations suggest that a Donnan equilibrium is established under these experimental conditions, and demonstrate that the tectorial membrane acts as a separate phase in vitro. It may not be valid, therefore, to assume that the membrane is electrically and ionically transparent in vivo.

Animals↗
PubMed1980

Embryogenesis of the mammalian inner ear. III. Formation of the tectorial membrane of the CBA/CBA mouse in vivo and in vitro.

The development of the tectorial membrane in the basal coil of the cochlea has started already in the 15th gestational day inner ear and has reached a considerable thickness and maturation at birth. The development of the tectorial membrane occurs synchronously in in vivo labyrinths and the in vitro material cultured to an age corresponding to birth. At least during this part of the development the formation of the tectorial membrane is independent of the specific composition of endolymph. In the in vivo material a secretory maximum was reached on the 18th gestational day, whereafter the secretory activity was low, especially after birth. In the in vitro specimens, however, a rather constant secretion of material occurred also post partum, which indicates a lack of control mechanisms during in vitro conditions. A complete maturation of the tectorial membrane did not occur in vitro. When passing the point of time corresponding to birth, in the in vitro inner ear explants the gross structure of the tectorial membrane is only slightly changed. In vivo a mature configuration of the tectorial membrane is observed on the 14th DAB (day after birth).

Animals↗
PubMed1976

Attachment of the inner sensory cell hairs to the tectorial membrane. A scanning electron microscopic study.

The residue of tectorial membrane insertion of cochlear inner sensory cell hairs was studied under a scanning electron microscope. In addition to the clear imprints resulting from outer sensory cell hair insertions, an adjacent medial row of bow-shaped imprints was noted on the base of the tectorial membrane. The relative position of these imprints corresponded to the location and the size of the inner cell hairs. These imprints were thus thought to arise from the insertion of the inner sensory hair cells. Such imprints were found only in the lower turns of the cat's cochlea, but not on the guinea pig tectorial membrane. Thus an actual physical contact between the tectorial membrane and the inner sensory cell hiars may exist in some species but not in others, and when there is physical contact, it is thought to be less firm than that of the outer sensory hair cells.

Animals↗
PubMed1985

[Formation of the tectorial membrane of the cochlear canal during the embryogenesis of birds].

By means of electron microscopy formation of the tectorial membrane of the cochlear canal and differentiation of the cells participating in the process (supporting cells of the basilar papilla and anterior homogeneous cells--AHC) have been studied in chick embryos. The AHC, to which the tectorial membrane is fixed, produce fine fibrillar material, included into the composition of the tectorial membrane. The cells mentioned form a number of cytoskeletal structures connected with the mechanical function of the tectorial membrane. Besides the network of the tonofilaments, gradually filling cytoplasm of the AHC, some peculiar attachings in the form of collagenous fibrillar bundles are revealed, they reach the AHC from the sublying connective tissue and have a direct contact with the basal membrane of the cells. The beginning of the tectorial membrane formation precedes the formation of the cytoskeletal structures. The latter appear only when the mass of the tectorial membrane, and hence, the mechanical loading on the AHC is great enough.

Animals↗
PubMed1987

Polypeptide composition of the mammalian tectorial membrane.

The effects of the enzymes collagenase, pepsin, chondroitinase ABC and keratanase on the polypeptide composition of the mammalian tectorial membrane have been analysed using one dimensional SDS-polyacrylamide gel electrophoresis (SDS-PAGE). After reduction at least ten polypeptides can be consistently and clearly recognized in SDS gels with molecular weights relative to globular protein standards of 245, 235, 190, 165, 155, 145, 100, 93, 60-73 and 35-49 kDa. With the exception of the 60-73 and 35-49 kDa bands all these polypeptides are sensitive to digestion with bacterial collagenase. The 235, 165, 155, 145 and 93 kDa bands also resist degradation by cold, acidic pepsin. Amino acid analysis of whole tectorial membranes demonstrates that glycine accounts for nearly 25% of the total amino acid content, that proline, hydroxyproline and hydroxylysine are present and that amine sugars can be detected in fairly high concentrations. Estimates based on hydroxyproline content suggest that collagens account for 25-50% of the total tectorial membrane protein. Immunoblotting techniques demonstrate the presence of polypeptides cross reacting with antisera to Type II collagen, Type IX collagen and Type V collagen. Results from immunohistochemical studies confirm that these polypeptides are present in the tectorial membrane and are not contaminants of the isolation procedure. Collagenase treatment of tectorial membranes reveals the presence of an additional non-collagenous polypeptide with an apparent molecular weight of 173 kDa on 7.5% polyacrylamide gels, and polydisperse high molecular weight material spreading over a broad range at the top of the gels. This high molecular weight material and the 173, 60-73 and 35-49 kDa non-collagenous polypeptides are pepsin sensitive and all bind wheat germ agglutinin (WGA) suggesting that they contain N-acetyl glucosamine. The 173 kDa band also binds soybean agglutinin (SBA) suggesting the presence of N-acetyl galactosamine. In the absence of reducing agent the 173 and 60-73 kDa bands are no longer observed and high molecular weight material forming a broad band at the top of the separating gel is seen. The electrophoretic behaviour of this non-collagenous, glycosylated, disulphide bonded, high molecular weight material is altered by treatment with keratanase but not by chondroitinase ABC. The results of this study indicate the tectorial membrane contains at least three different collagen types and, in addition to these collagenous proteins, several non-collagenous, glycosylated polypeptides that may account for as much as 50% of the total tectorial membrane protein.

Acetylgalactosamine↗
PubMedDate not supplied

The proteins of normal and abnormal tectorial membranes.

The proteins of the normal mouse tectorial membrane were analysed using SDS polyacrylamide gel electrophoresis. Three major protein bands were found with molecular weights of 145 000, 155 000 and 165 000, together with a number of minor components. Abnormal tectorial membranes from thiouracil-treated mice and from Deafness, Jerker, and Varitint-Waddler mutant mice were also examined in this way, but no evidence could be found to support the hypothesis that the distortion of the membranes might be due to an abnormal protein constitution. No PAS-positive material could be demonstrated in gels of normal membranes.

Animals↗
PubMed2005

A deafness mutation isolates a second role for the tectorial membrane in hearing.

Alpha-tectorin (encoded by Tecta) is a component of the tectorial membrane, an extracellular matrix of the cochlea. In humans, the Y1870C missense mutation in TECTA causes a 50- to 80-dB hearing loss. In transgenic mice with the Y1870C mutation in Tecta, the tectorial membrane's matrix structure is disrupted, and its adhesion zone is reduced in thickness. These abnormalities do not seriously influence the tectorial membrane's known role in ensuring that cochlear feedback is optimal, because the sensitivity and frequency tuning of the mechanical responses of the cochlea are little changed. However, neural thresholds are elevated, neural tuning is broadened, and a sharp decrease in sensitivity is seen at the tip of the neural tuning curve. Thus, using Tecta(Y1870C/+) mice, we have genetically isolated a second major role for the tectorial membrane in hearing: it enables the motion of the basilar membrane to optimally drive the inner hair cells at their best frequency.

Acoustic Stimulation↗