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PubMed1958

Electron microscope studies of the human epidermis: the clear cell of Masson (dendritic cell or melanocyte).

The human epidermis has been studied by electron microscopy following osmium tetroxide and potassium permanganate fixation. An anatomically distinct cell in the human epidermis has been demonstrated with features similar to the melanocyte of the hair bulb described by Barnicot, Birbeck and Cuckow (3). It is dendritic in form and does not contain tonofilaments. "Intercellular bridges" are not formed. The mitochondria are larger and more numerous than those of other epidermal cells and the endoplasmic reticulum is more complex. Some of these cells contain melanin but others are melanin-free. The cell has been interpreted as being identical with the dopa-positive, clear cell of Masson (dendritic cell of Bloch or melanocyte). We have found that many membranous structures in the human epidermis are better preserved by permanganate fixation than by osmium tetroxide fixation.

Animals↗
PubMedDate not supplied

Hair cells without supporting cells: further studies in the ear of the zebrafish mind bomb mutant.

Each sensory hair cell in the ear is normally surrounded by supporting cells, which separate it from the next hair cell. In the mind bomb mutant, as a result of a failure of lateral inhibition, cells that would normally become supporting cells differentiate as hair cells instead, creating sensory patches that consist of hair cells only. This provides a unique opportunity to pinpoint the functions for which supporting cells are required in normal hair cell development. We find that hair cells in the mutant develop an essentially normal cytoskeleton, with a correctly structured hair bundle and well-defined planar polarity, and form apical junctional complexes with one another in standard epithelial fashion. They fail, however, to form a basal lamina or to adhere properly to the adjacent non-sensory epithelial cells, which overgrow them. The hair cells are eventually expelled from the ear epithelium into the underlying mesenchyme, losing their hair bundles in the process. It is not clear whether they undergo apoptosis: many cells staining strongly with the TUNEL procedure are seen but do not appear apoptotic by other criteria. Supporting cells, therefore, are needed to hold hair cells in the otic epithelium and, perhaps, to keep them alive, but are not needed for the construction of normal hair bundles or to give the hair bundles a predictable polarity. Moreover, supporting cells are not absolutely required as a source of materials for otoliths, which, though small and deformed, still develop in their absence.

Animals↗
PubMed1998

Gap junction change in supporting cells of the organ of Corti with ryanodine and caffeine.

It has been demonstrated that the gap junctions of the supporting cells of the organ of Corti are controlled by H+ and Ca2+. Inside these cells there is a tubular structure. It is supposed that this network is endoplasmic reticulum. Calcium release from inside the cells, and the effect of calcium on the gap junctions of these cells, were investigated under whole cell clamping application of ryanodine and caffeine. Membrane capacitance and membrane resistance were calculated, with corrections for changes in whole cell parameters. Ryanodine-treated cells (1 microM-10 mM), caffeine-treated cells (5 mM 500 nM) and A23187-treated cells were uncoupled at their gap junctions. Therefore, Ca2+ plays a role in the uncoupling of the gap junctions in supporting cells of the organ of Corti from inside the cells.

Animals↗
PubMed2006

Distribution of pendrin in the organ of Corti of mice observed by electron immunomicroscopy.

The distribution of pendrin, which is encoded by the Pendred syndrome gene, has been investigated immunohistochemically in the inner ear. In the cochlea, pendrin has been found in the spiral prominence, external sulcus cells, Hensen's cells and Claudius cells, but its expression in the organ of Corti remains unclear. We examined whether pendrin localizes in the organ of Corti by postembedding immunogold analysis. In the organ of Corti, gold particles were clearly observed in outer and inner hair cells, including the stereocilia. The density of the particles was especially high in the cuticular plates of the hair cells. Gold particles were also detected in the external sulcus, in part of the spiral ligament adjacent to the external sulcus, in supporting cells, and in the spiral ganglion of the cochlea. Our study revealed that pendrin occurs in the organ of Corti. The role of pendrin in the organ of Corti and its association with the Cl- or pH regulation of neurotransmission require further study.

Analysis of Variance↗
PubMed2000

[Morphological observation and electrophysiological properties of isolated Deiters' cells from guinea pig cochlea].

OBJECTIVE: To dissociate viable isolated Deiters' cells from guinea pig cochlea and perform morphological measurements under inverted microscope; To study electrophysiological properties of Deiters' cells. METHOD: Deiters' cells were dissociated from guinea pig cochlea by papain digestion followed by trituration. Standard patch clamp methods were used to measure whole cell capacitance, zero current potential, reversal potential and potassium ion currents of Deiters' cells in normal external solution. Equations were used to compute the relative membrane permeability ratio of Deiters' cell to K+ and Na+ (PK/PNa) and the potassium equilibrium potential (EK). RESULT: Isolated Deiters' cell looks like a comma, which was divided into cell body, stem and Deiters' phalanx and the nucleus is at about center of its body. Cell length of Deiters' cell was (61.6 +/- 20) microM (mean +/- SEM, n = 45), whole cell capacitance was (27.5 +/- 9.2) pF (n = 28), zero current potential was (-20 +/- 1.8) mV(n = 28), reversal potential was (-64.3 +/- 2.9) mV (n = 24), PK/PNa = 25.4:1 and EK = -82.4 mV. Potassium currents of Deiters' cells were recorded in normal external solution. CONCLUSION: The situation of Deiters' cells in cochlea could be inferred according to length of them indirectly. The ion channel of Deiters' cells was mainly K+ selective. Voltage-dependent and outwardly rectifying potassium currents were prominent in Deiters' cells.

Animals↗
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↗
PubMed1986

Intracellular recordings from supporting cells in the organ of Corti.

Horseradish peroxidase marking and intracellular recording techniques were utilized to examine whether the heterogeneity of supporting cell types is reflected in their electrical behavior. The magnitudes of ac and dc response components were compared to their extracellular counterparts. The relationships among these potentials seem to be governed by the cell's location within the organ of Corti.

Animals↗
PubMed1997

Morphologic evidence for innervation of Deiters' and Hensen's cells in the guinea pig.

The presence of nerve fibers and terminals among Deiters' and Hensen's cells of the organ of Corti of the adult guinea pig is demonstrated using immunostaining for synaptophysin and neurofilaments, acetylcholinesterase histochemistry, and transmission electron microscopy. These nerve terminals appeared to form chemical synapses with Deiters' and Hensen's cells. Nerve fibers and synapses were more common in the apical as compared to the basal cochlea. The terminals were often present on basal appendages of Hensen's cells, which were rich in mitochondria and often contained a Golgi apparatus and dense core vesicles. Electron microscopy and immunostaining for neurofilaments showed that most Hensen's cells in the apical cochlea received innervation. Few of the nerve fibers and terminals were positive for acetylcholinesterase, which suggests that they were not collaterals of cholinergic olivocochlear fibers. The density of these fibers, as shown by immunohistochemistry for neurofilaments, was far greater than previous reports of GABA-ergic fibers, which suggests that they were not GABA-ergic olivocochlear fibers. The role of such fibers and synapses with supporting cells of the outer hair cell area is unknown. Determination of the origins and functions of these fibers will provide new insights into cochlear structure and function.

Acetylcholinesterase↗
PubMed2004

[Distribution of calcitonin gene-related peptide in guinea pig cochlea].

OBJECTIVE: To observe the distribution of CGRP in guinea pig cochlea. METHOD: CGRP was labeled by immunostaning technique. Distribution of CGRP immunoreactivity was observed with light microscopy. RESULT: CGRP immunoreactivity was located in SGN, nerve fibers at osseous spiral lamina, stria vascularis, IHC, adjacent area of OHC and Deiters' cells. CONCLUSION: CGRP distributes extensively in guinea pig cochlea. CGRP may play an important role as neurotransmitter and/or neuromodulator to hearing function by modulating HC, supporting cells, SGN and other neurons along the process of auditory nerve. It may have effect on on cochlear blood flow, too.

Animals↗
PubMed2002

Expression of members of Wnt and Frizzled gene families in the postnatal rat cochlea.

The functioning of the mammalian cochlea is entirely based on its mechanical properties, which are supported by a highly complex tissue architecture resulting from the precise arrangement of sensory hair cells and non-sensory supporting cells. Growing evidence indicates that evolutionary conserved signaling pathways are involved in inner ear development and in the differentiation of its diverse cell types. We investigated whether members of the Wnt and Frizzled gene families, which play key roles in a wide variety of cellular and developmental processes, are expressed in the postnatal rat cochlea. A PCR screening of a rat cochlea cDNA library performed with degenerate primers allowed us to isolate five members of the Wnt gene family (RWnt-2B, -4, -5A, -5B, and -7A) and six members of the Frizzled gene family (Rfz1, Rfz2, Rfz3, Rfz4, Rfz6, Rfz9). In situ hybridization and immunocytochemistry experiments demonstrated that RWnt-4, -5B, -7A have distinct, although partly overlapping, expression patterns in the juvenile rat cochlea. These results suggest that the Wnt-Frizzled signaling pathway could be involved in several aspects of late cochlear differentiation and/or auditory function.

Aging↗
PubMed1998

Selective expression of mercurial-insensitive water channel (AQP-4) gene in Hensen and Claudius cells in the rat cochlea.

We investigated the cellular localization of mercurial-insensitive water channel (MIWC) mRNA in the rat cochlea. MIWC gene expression was detected in the supporting cells in Corti's organ. The function of these supporting cells is not clear, but the results suggest that they reabsorb water and play a role in maintaining the ionic balance of inner ear fluids.

Animals↗
PubMed1994

Ultrastructural differentiation of the first Hensen cell in the gerbil cochlea as a distinct cell type.

BACKGROUND: The mammalian cochlea contains beneath and lateral to outer hair cells, several types of supporting cells. The function of these cells has not been explained beyond providing a structural base. METHODS: The supporting cells of gerbil cochlea were examined by electron microscopy with a view to elucidating their biologic activity on the basis of cytologic structure. RESULTS: Ultrastructural examination differentiated the laterally located Hensen cells from their medial neighbor connected to the third Deiters cell. The latter cell formed a cover to the outer tunnel between Hensen and Deiters cells, appeared not to reach the basilar membrane, and exhibited a denser cytosol and more mitochondria, compared to Hensen cells. In these respects the cell observed here to cover the outer tunnel, corresponded with the tectal cell described by Henson et al. (1983) in the mustache bat, but not heretofore documented in other animals. CONCLUSIONS: This distinctive cell in the gerbil differed in displaying unique villus-like structures which projected from the basomedial surface and are referred to as fimbriae. The fimbriae and interspersed filopodia largely filled outer tunnel space and expanded the cell's basal surface. The amplification of basal plasmalemma by fimbriae and their content of mitochondria testify to a role for the tectal cell in ion resorption and an influence on ion content and volume of outer tunnel fluid.

Animals↗
PubMed1998

Nucleation and capture of large cell surface-associated microtubule arrays that are not located near centrosomes in certain cochlear epithelial cells.

This report deals with the as yet undetermined issue of whether cell-surface associated microtubules in certain cochlear epithelial cells are centrosomally nucleated and subsequently migrate to microtubule-capturing sites located at the surface regions in question. Alternatively, the cells may possess additional nucleating sites which are noncentrosomal and surface-associated. These alternative possibilities have been investigated for highly polarised epithelial cells called supporting cells in the mouse and guinea pig organ of Corti using antibodies to pericentrin and gamma-tubulin. There is substantial evidence that both proteins are essential components of microtubule-nucleating sites in cells generally. Each mature supporting cell possesses a large microtubule array that is remotely located with respect to its centrosome (more than 10 microns away). The antibodies bind to a cell's centrosome. No binding has been detected at 2 other microtubule-organising centres that are associated with the ends of the centrosomally-remote microtubule array while it is being constructed. Such arrays include thousands of microtubules in some of the cell types that have been examined. If all a cell's microtubules are nucleated by its centrosome then the findings reported above imply that microtubules escape from the centrosomal nucleating site and migrate to a new location. Furthermore capture of the plus and minus ends of the errant microtubules is taking place because both ends of a centrosomally-remote microtubule array are attached to sites that are precisely positioned at certain cell surface locations. Minus ends are locating targets with an exactitude comparable to that which has been demonstrated for plus ends in certain cell types. These cells apparently operate a single control centre strategy for microtubule nucleation that is complemented by precise positioning of plus and minus end-capturing sites at the cell surface.

Animals↗
PubMed1986

Cytoskeletal organization in the supporting cell of the guinea pig organ of Corti.

The rapid-freeze, deep-etch method was used to visualize the three-dimensional organization of cytoskeletons in the supporting cells of the guinea pig organ of Corti. Deep-etched replicas showed that both the head and basal portions of the pillar cell were composed of a filamentous network consisting of several kinds of fibrous elements, into which numerous microtubules and actin filaments were tightly inserted. Myosin S1-decoration showed that the main constituent element in such filamentous networks in the basal portion of the pillar cell was the actin and tiny cross-bridges interconnected the randomly oriented adjacent actin filaments.

Actin Cytoskeleton↗