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Results for “Cochlear Duct”

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PubMed1993

[Immunohistochemical study of proteoglycans and collagens in the mouse cochlear duct].

Immunohistochemical studies of proteoglycans and collagens (type I and type IV) in the cochlear duct, and of the effects of cisplatin (CDDP), were performed. In cells of the organ of Corti and in the middle layer of the stria vascularis, heparan sulfate proteoglycan (HSPG) and collagens (type I and IV) or collagen-like substances were found. HSPG in these locations appeared to play important roles in the production of auditory sense. The tectorial membrane contained HSPG and collagens (type I and IV). However, no data supporting the concept that elements of the tectorial membrane are derived from interdental cells was obtained. In the basilar membrane, no HSPG, chondroitin sulfate (Chs), or collagens (type I and IV) were detected. The unique structures containing these substances reacted strongly with anti-HS (heparan sulfate), anti-HSPG-CP (core protein) and anti-collagen (type I and IV) antibodies that developed in the middle layer of the stria vascularis after the administration of CDDP. However, no change was observed in the tectorial membrane, the spiral prominence, the basilar membrane, or the spiral limbus. The decrease in HSPG in cells of the organ of Corti, and the changes in the stria vascularis, may help solve the well known contradiction between the severity of morphological damage and of the hardness of hearing.

Animals↗
PubMed1990

Quantitative immunogold localization of Na+,K(+)-ATPase alpha-subunit in the tympanic wall of rat cochlear duct.

Ultrastructural localization of Na+,K(+)-ATPase was quantitatively investigated in the tympanic wall of rat cochlear duct by use of the protein A-gold method, using an affinity-purified antibody against the alpha-subunit of rat kidney Na+,K(+)-ATPase. A moderate number of gold particles were found on the basolateral membrane of the interdental cells of the spiral limbus. A small number of gold particles were found on the basolateral surfaces of the border cells and Hensen's cells. On the inner and outer sensory hair cells, however, the plasma membranes were rarely labeled by gold particles. The general pattern of labeling densities in cochlear structures determined here and in a previous communication from our laboratory shows good correlation with the distribution of Na+,K(+)-ATPase activity as previously estimated biochemically, cytochemically, and autoradiographically.

Animals↗
PubMed1989

Quantitative immunocytochemical localization of Na+,K+-ATPase alpha-subunit in the lateral wall of rat cochlear duct.

Ultrastructural localization of the alpha-subunit of Na+,K+-ATPase on the lateral wall of rat cochlear duct was investigated quantitatively by the protein A-gold method, using affinity-purified antibody against the alpha-subunit of rat kidney Na+,K+-ATPase. In the stria vascularis, gold particles were sparse over the endolymphatic luminal surface of the marginal cells but were numerous over the basolateral membrane. The labeling density of the basolateral membrane was almost equal to that of the same domain of the distal tubule cells of kidney. The intermediate cells were studded with a large number of gold particles on the plasma membrane domain facing the basolateral domain of the marginal cells. On the luminal surfaces of the other epithelial cells, including those of Reissner's membrane, no significant amount of gold particles was found. Many gold particles were localized on all the plasma membranes of the spiral prominence stromal cells and on the intracellular membrane domain of the external sulcus cells.

Animals↗
PubMed1984

The development of stereociliary bundles in the cochlear duct of chick embryos.

The differentiation of hair cell stereociliary bundles was investigated during early stages of embryonic development in the chick cochlear duct. The ultrastructural characteristics of the differentiating stereocilia and the position of the hair cells at the time of their differentiation were determined with scanning (SEM) and transmission (TEM) electron microscopy. Stereocilia were first identifiable with SEM as early as embryonic day 6 (stage 29) in only the distal region of the basilar papilla. By embryonic day 7.5 (stage 32) stereocilia were detected with both SEM and TEM on hair cells located in the distal two-thirds of the basilar papilla. Stereociliary bundles were recognizable throughout the entire basilar papilla by embryonic day 9 (stage 35). At this stage the hair cells exhibited a distal-to-proximal gradient in the cell surface area and the number of stereocilia on each hair cell. These results suggest that there is a distal-to-proximal wave of hair cell differentiation which occurs at a very early time period in the development of the chick cochlea. Both the timing and the direction of the stereociliary differentiation contrast with previous ultrastructural reports of avian hair cell development, yet compare favorably with the patterns of functional development in the auditory system.

Animals↗
PubMed1985

[Light and electron microscopic studies on the development of the spiral prominence of the cochlear duct of the fetal guinea pig].

The anlage of the spiral prominence can be seen on the 37th day of development as a small protrusion of the epithelium towards the lumen of the cochlear duct. During the further progress, the spiral prominence more distinctly protrudes by augmentation of the vascularized connective tissue. In the epithelial cells pinocytotic vesicles near the plasmalemma are seen earliest lateral and basal on the 37th day, apical on the 39th day. The epithelial cells send basal cytoplasmic extensions towards the connective tissue. Starting on the 44th day, small invaginations of connective tissue extend into the epithelium, remaining separated from the epithelial cells by the basal lamina. Until the 48th day, the monostratified epithelium remains columnar, thereafter it changes to cuboidal or flat. Towards the end of the development, the invaginations of the connective tissue nearly reach the surface of the epithelium, being separated from the endolymph by a small epithelial area.

Animals↗
PubMed1993

Apparent apical endolymphatic hydrops: computer-aided three-dimensional reconstruction and histologic study of the apical turn of the cochlear duct.

Computer-aided three-dimensional reconstruction of the apex of a cochlea and microscopic evaluation of 14 clinically and histologically normal temporal bones were used to demonstrate that what appears to be distention of Reissner's membrane is normal anatomy. The apparent distention is the transition area between the circular insertion of the apex of the cochlear duct and the rest of Reissner's membrane, which is straight.

Adult↗
PubMedDate not supplied

Single-cell layer membrane covering the degenerated cochlear duct after perilymphatic perfusion of streptomycin.

Ultrastructural changes of the extrasensory epithelium in the scala media of guinea pig cochleae were observed from 3 to 137 days after perilymphatic perfusion with 20% streptomycin. The degeneration started in the organ of Corti, progressed to the interdental cells and roots of the outer sulcus cells and finally involved other epithelial cells such as Claudius and the inner and outer sulcus cells. In the final stage, except for the stria vascularis and Reissner's membrane, all epithelial cells which lined the cochlear duct were replaced by a single-cell layer membrane which originated medianly from the epithelial cells of Reissner's membrane and laterally from the superficial outer sulcus cells.

Animals↗
PubMed1996

Ultrastructural localization of G-protein GS in the lateral wall of the guinea pig cochlear duct.

Immunocytochemical localization of a GTP-binding protein, Gs, in the various cells of the lateral wall of guinea pig cochlear duct was investigated using a post-embedding immunogold method with antibody raised against a synthetic decapeptide (RMHLRQYELL) encoding the C-terminus of the alpha-subunit of Gs. In the stria vascularis, labeling was observed on the basolateral membrane infoldings of marginal cells, on the juxtaposed membrane of intermediate cells, and on the cell membrane of basal cell. In contrast, no significant labeling was observed on the luminal membrane of marginal cells. Immunoreactivity also was detected on the cell membranes of various other cells. These include spiral prominence epithelial cells, fibrocytes of spiral ligament, external sulcus cells, and epithelial and mesothelial cells of Reissner's membrane. Adenylylcyclase has been functionally implicated in some of the cell types with membranes labeled in this study. The significance of these findings is briefly discussed.

Adenylyl Cyclases↗
PubMed1978

[Light and electron microscopic studies of the greater epithelial ridge and its relationship to the developing tectorial membrane in the cochlear duct of the guinea pig (author's transl)].

In early stages of fetal development (36th day, 3rd turn) the thickening of the epithelium at the basal side of the cochlear duct forms two ridges. Later in fetal development the laterally situated lesser epithelial ridge forms the major part of the organ of Corti, whereas the medially situated greater epithelial ridge contributes only a small part to this organ. The medial part of the greater ridge consists of the columnar inner supporting cells, which bear a border of closely packed microvilli at their upper surface. Up to the time of the opening of the internal spiral sulcus in the 48th day of fetal development, there is a close spacial relationship between microvilli and filaments of the tectorial membrane. We conclude that the inner supporting cells contribute to the formation of the tectorial membrane. However, thus far we cannot entirely exclude a different possibility, that the inner supporting cells absorb material of the tectorial membrane. During the opening of the sulcus spiralis internus the inner supporting cells become considerably smaller, some of them undergo complete destruction by cytolysis, with pyknosis and karyorrhexis.

Animals↗
PubMed2005

Cell transplantation to the auditory nerve and cochlear duct.

We have developed a technique to deliver cells to the inner ear without injuring the membranes that seal the endolymphatic and perilymphatic chambers. The integrity of these membranes is essential for normal hearing, and the technique should significantly reduce surgical trauma during cell transplantation. Embryonic stem cells transplanted at the internal auditory meatal portion of an atrophic auditory nerve migrated extensively along it. Four-five weeks after transplantation, the cells were found not only throughout the auditory nerve, but also in Rosenthal's canal and the scala media, the most distal portion of the auditory nervous system where the hair cells reside. Migration of the transplanted cells was more extensive following damage to the auditory nerve. In the undamaged nerve, migration was more limited, but the cells showed more signs of neuronal differentiation. This highlights an important balance between tissue damage and the potential for repair.

Animals↗