Biomedical subjects

S S Spicer

Publications and source records attributed to S S Spicer.

At least 19 recordsLinked to original sources

PubMed1999

Immunohistochemical localization of Ca2+/Calmodulin-dependent protein kinase IV in outer hair cells.

A smooth membrane system consisting of subsurface cisternae (SSC) underlies the lateral plasmalemma of auditory outer hair cells (OHCs). The SSC contain Ca-ATPase and are regarded as an intracellular Ca2+ reservoir like the sarcoplasmic reticulum of myocytes. Recently, it has been demonstrated that Ca-ATPase activity in sarcoplasmic reticulum is regulated by Ca2+/calmodulin-dependent protein kinases (CaM kinases). Here we investigated the presence of CaM kinases in OHCs and their possible association with the SSC. Inner ears collected from adult gerbils and from neonates at 2-day intervals between 0 and 20 days after birth were immunostained with antibodies specific for different CaM kinases. A polyclonal antiserum against CaM kinase IV yielded a strong immunostaining reaction along the lateral wall of OHCs. The staining appeared after the tenth postnatal day and continued into adulthood. No other site in the inner ear, including cochlear inner hair cells and vestibular hair cells, was reactive. The kinase's apparent association with the SSC strongly supports its involvement in intracellular Ca2+ homeostasis and suggests a role in regulating the OHCs' slow motile responses.

Aging↗

PubMed1998

Cytologic evidence for mechanisms of K+ transport and genesis of Hensen bodies and subsurface cisternae in outer hair cells.

UNLABELLED: A system commonly termed the tubulocisternal endoplasmic reticulum (TCER), but designated here the canalicular reticulum (CR), occurs selectively in ion-transporting epithelia, in which it is interpreted as facilitating the transcellular diffusion of ions. Mechanoelectrical transduction in the cochlear outer hair cells (OHCs) depends on the apical influx and the subsequent basolateral efflux of K+. Cytologic structures that possibly mediate K+ transport in gerbil OHCs were investigated here. METHODS: Cochleas were fixed primarily with glutaraldehyde and secondarily with reagents for demonstrating TCER or were fixed with a ferrocyanide-osmium tetroxide solution to preserve intracellular membranes. The distribution of membranous structures retained with these techniques was examined by using electron microscopy. RESULTS: Secondary fixation with osmium tetroxide-ferrocyanide permitted ultrastructural demonstration in OHCs of increased numbers of Hensen bodies and newly detected membranous systems, including CR, linear cisternae, small clusters of cytosolic vesicles and complexes of canaliculi, segmented cisternae, and mitochondria. CR filling an apical stratum beside and below the cuticular plate and contacting laterally the uppermost subsurface cisternae (SSC) was situated to sequester and transport the apical K+ influx that attends the acoustically generated receptor potential and the silent current. The close association of CR with numerous, highly developed Golgi bodies exclusively in the apex of the cell suggested genesis of CR from Golgi cisternae. Nonbranching, linear cisternae occupied a lower cell stratum and spread from CR laterally to a more inferior region of the SSC. Small clusters of vesicles in the central cytosol resembled Hensen bodies in their envelopment by branching canaliculi and segmented cisternae in close association with mitochondria. Viewing the vesicles in Hensen bodies and the small clusters as functioning like most other cytoplasmic vesicles in transport of cell membrane permitted the interpretation that these vesicles move nascent membrane from the canalicular-mitochondrial complex to the SSC. Other small clusters of vesicles contacted the innermost layer of the SSC, often at cisterna-depleted foci in which the vesicles appeared to either replenish the SSC or arise in the course of its turnover. Proximity of multivesicular bodies and lysosomes to small vesicle clusters in foci of depleted SSC implicated the lysosomes in digesting vesicles released from the SCC. Populations of unique, large, lysosome-like bodies and of small, dense bodies in the upper cytosol of OHCs appeared to be involved in different catabolic pathways mediating the turnover ofSSC, CR, and other structures. CONCLUSIONS: Cochlear OHCs contain previously unrecognized membranous organelles that facilitate ion transport and presumably contribute thereby to mechanoelectrical transduction. Vesicles in small clusters and Hensen bodies arise from complexes of canaliculi, cisternae, and mitochondria and contribute membrane to the genesis of the SSC.

Animals↗

PubMed1998

Evidence for a medial K+ recycling pathway from inner hair cells.

K+ effluxed from outer hair cells and their nerves is thought to flow laterally to strial marginal cells for recycling into scala media. Observations reported here provide evidence that K+ effluxed from inner hair cells and inner radial nerves travels medially through border cells, inner sulcus cells (ISCs), limbal fibrocytes and interdental cells (IDCs) for return to endolymph. Morphologic features of ISCs in the medial route resembled those of Hensen and Claudius cells in the lateral indicating an ion transport role for ISCs like that of Hensen and Claudius cells. Na,K-ATPase in plasmalemma of IDCs testified to their capacity to resorb and transport K+ through their known gap junctions. IDCs were differentiated into three subgroups. The most lateral IDCs formed short and long columns. Long columns contacted the medialmost ISC inferiorly and the undersurface of the tectorial membrane superiorly providing thereby a potential transcellular route for K+ transit from ISCs to endolymph. Short columns faced inner sulcus below and tectorial membrane above and accordingly possessed cells with opposite polarity at the bottom and top of the column. Short columns thus appeared situated to resorb electrolytes from limbal stroma for release into inner sulcus and beneath tectorial membrane at opposite ends of the column. The central IDCs were positioned for resorbing and transporting K+ effluxing from the Na,K-ATPase-rich stellate fibrocytes which spread toward the IDCs from near the inner sulcus. The most medial IDCs lined cuplike invaginations near the attachment of Reissner's membrane and lay apposed to light fibrocytes located between supralimbal fibrocytes and the medial IDCs. Content of Na,K-ATPase and position in the K+ transport route likened the limbal stellate fibrocytes to the spiral ligament type II fibrocytes and supralimbal fibrocytes to suprastrial fibrocytes in the lateral wall. From content of creatine kinase and position in the transport path, limbal light fibrocytes appeared analogous to spiral ligament type I fibrocytes. The additional finding that limbal fibrocytes showed unchanged or upregulated Na,K-ATPase immunoreactivity in aged gerbils with strial atrophy provided further evidence for an independent medial transport route and for the survival of inner hair cells in presbyacusis.

Aging↗

PubMed1997

Golgi-canalicular reticulum system in ion transporting fibrocytes and outer sulcus epithelium of gerbil cochlea.

BACKGROUND: Five types of highly specialized fibrocytes have been identified in the spiral ligament of the gerbil cochlea. Type I, II, and IV fibrocytes function in cycling back to the stria vascularis K+ effluxed from outer hair cells and nerves during auditory transduction. Thus, evidence exists for a transcellular path of K+ movement from outer sulcus cells through fibrocytes to the strial interstitial space, but a mechanism for facilitating such ion flow within the cells has not been elucidated. METHODS: The spiral ligament of glutaraldehyde-osmium tetroxide-fixed and Epon-embedded gerbil cochlea was examined by transmission electron microscopy. RESULTS: Ultrastructural examination disclosed an extensive membrane limited reticulum in the cytoplasm of type I, II, IV, and V fibrocytes of the lateral wall and in outer sulcus cells and their root processes. This system resembled the tubulocisternal endoplasmic reticulum present in some ion-transporting epithelia but appeared more to constitute a network of canaliculi and is referred to as the canalicular reticulum (CR). Many typical small Golgi complexes invariably accompanied the CR in the fibrocytes and sulcus cells, as we have found to be true of other epithelia known to contain CR and function in ion transport. Numerous mitochondria populated cytosol-containing CR. CONCLUSIONS: The data support the concept of transcellular K+ flux in type I, II, IV, and V fibrocytes and outer sulcus cells in the cochlea and lend credence to the view of CR as functioning in the movement of ions through cells. The constant and precise association of Golgi complexes with CR in the different cell types implies a functional relationship possibly concerned with biosynthesis of CR by Golgi elements, and the abundance of mitochondria near CR indicates an energy requirement for function of the reticulum or its biosynthesis.

Animals↗

PubMed1997

Increased laminin deposition in capillaries of the stria vascularis of quiet-aged gerbils.

The distribution of laminin (LA) and type IV collagen (IV-C) in the gerbil inner ear was investigated by light and electron microscopic immunohistochemistry. Changes in protein expression were assessed from birth to old age to determine the relation of these constituents to maturation of the cochlea and development of presbyacusis. The distribution of LA paralleled that of IV-C during postnatal development, and both were visualized in the basement membrane (BM) of endothelial, epithelial and spiral ganglion cells in neonatal and young adult gerbils. Immunopositive BM underlying the stria vascularis disappeared at 8-12 days after birth coincident with the development and maturation of the strial capillaries. Immunoreactivity for LA afforded an index to the thickness of the BM and was found to increase with age only in the BM of strial capillaries. At 6 months of age, occasional strial capillaries in the apex of the cochlea showed thickening of the LA-positive BM. Abnormal deposition of LA in strial capillary BM spread to lower turns and increased in prevalence with advancing age, affecting apical and basal more than middle cochlear turns. Thickening of the capillary BM appeared to precede capillary obstruction which eventuated in complete strial atrophy. Staining for IV-C in the walls of the strial capillaries did not increase with age. The data show that LA and IV-C play important roles in postnatal development of the cochlea and that LA deposition increases with age only in the BM of strial capillaries.

Aging↗

PubMed1997

Immunoglobulin deposition in thickened basement membranes of aging strial capillaries.

The presence of immunoglobulins in the thickened basement membrane (BM) of aging strial capillaries was investigated as a possible indicator of autoimmunity in the genesis of atypical BM. Cochleas from young and old Mongolian gerbils raised in quiet were examined by immunostaining at the light microscopic level for IgG and IgM and for the BM components laminin (La) and type IV collagen (IV-C). Another age-graded series of cochleas was stained for IgG at the ultrastructural level. No immunoreactive IgG was detected in specimens from animals less than 6 months old. In contrast, 2 of 12 cochleas from 20- to 28-month-old gerbils and 11 of 20 cochleas from gerbils 30 months or older showed positive staining for IgG in strial capillary BM. IgM was not detected at any age. At the electron microscope level, no immunoreactive IgG was detected in the stria of cochleas younger than 30 months. However, labeling demonstrative of IgG was observed in the thickened BM of some strial capillaries in all six cochleas from gerbils older than 33 months. Lysosome-like granules in endothelial cells and the superiormost marginal cells also stained for content of IgG as did fibrillar material in edematous regions in the intrastrial space. In addition to showing accumulation of IgG, the findings confirm our prior demonstration of increased La deposition in the thickened strial capillary BM of all cochleas from old gerbils. The BM alterations appear confined to strial capillaries in old gerbils, since morphological observations and immunostaining for La and IgG failed to detect changes in BMs at any other site in a wide survey of aged gerbil organs including vessels in other regions of the affected cochleas. The results point more towards the development of an age-dependent permeability to IgG selectively in strial capillaries than to autoimmunity as an explanation of the IgG in BM.

Aging↗

PubMed1997

Age-related thickening of basement membrane in stria vascularis capillaries.

Ultrastructural examination was undertaken to investigate the pathogenesis of age-related atrophy of the stria vascularis (StV). Basement membrane (BM) thickness was increased in 65-85% of strial capillaries in gerbils aged 33 months or older and often exceeded by several-fold that observed in young controls. In an early stage of thickening the BM expanded slightly around the full capillary profile, after which nodular expansions of BM encircling slender cell processes were often observed at or near one or both poles of the elliptical vessel profile. As widening progressed, the BM consisted of 2-3 layers separated by cell processes in the nodules but fewer strata elsewhere. Association of slender processes of both endothelial cells and pericytes with focal thickening outside the process suggested their participation in genesis of the capillary lesion. In later stages of atrophy, pericytes degenerated and disappeared, while endothelial cells remained intact. Eventually, thick multilayered BM devoid of endothelial cells surrounded a narrow lumen occluded by debris. The age-related change in BM in the inner ear was confined to StV capillaries. Degenerative changes in StV epithelial cells occurred apparently as a secondary consequence of the capillary lesion. The pathologic alterations in marginal cells included extrusion of blebs from the luminal surface, separation and loss of basolateral interfoldings, alteration and depletion of mitochondria and nuclear pyknosis. At the end-stage of degeneration, the StV consisted of a simple or multiple layer of squamous cells lining the scala media.

Aging↗

PubMed1997

Expression patterns of ion transport enzymes in spiral ligament fibrocytes change in relation to strial atrophy in the aged gerbil cochlea.

Fibrocytes of the lateral wall function in conjunction with the stria vascularis (StV) to mediate cochlear ion homeostasis. Age-related changes in the expression patterns of ion transport enzymes in spiral ligament fibrocytes were investigated to ascertain their relation to metabolic presbyacusis in the gerbil. Immunoreactivity of fibrocytes for Na,K-ATPase (Na,K), carbonic anhydrase isozyme II (CA) and creatine kinase isozyme BB (CK) varied among and within cochleas from aged but not from young gerbils. The variable immunostaining was related to the extent and location of StV atrophy. Age-dependent degeneration and loss of Na,K in the StV occurred predominantly in the apex and lower base and hook of the cochlea, largely sparing more central regions. Immunostaining intensity for Na,K, CK, and CA in fibrocytes changed in relation to declines in strial marginal cell Na,K initially showing upregulation followed by downregulation. Spiral ligament fibrocytes in cochleas with more than two remaining normal turns often disclosed overexpression of CK in regions of strial atrophy. Conversely, CA in such cochleas was often increased in regions of normal StV adjacent to foci of atrophic StV. Senescent cochleas with two or fewer functional turns generally contained fibrocytes with diminished CK or CA immunoreactivity in regions of atrophic StV but in isolated instances exhibited fibrocytes with enhanced staining. Heightened staining for CK in type Ia fibrocytes underlying regions of complete or partial strial atrophy indicated an increased metabolic demand in fibrocytes in response to strial insufficiency. The findings provide further support for the role of spiral ligament fibrocytes in cochlear fluid and ion homeostasis.

Aging↗

PubMed1996

Differentiation of glycoconjugates localized to sensory terminals and selected sites in brain.

Distribution of complex carbohydrates in the peripheral and central nervous systems was investigated cytochemically with a lectin that binds specifically to terminal alpha GalNAc and with monoclonal antibodies against carbohydrate epitopes, including glucuronic acid 3-SO4 and chondroitins 6-SO4 and 4-SO4. Comparative staining with these methods differentiated and partially characterized several glycoconjugates in various sites and allowed a comparison of chemical heterogeneity to neural specialization. Distal terminals of sensory neurons concerned with hearing, balance, taste, touch, and sight expressed glucuronyl 3-SO4, which apparently was present in an undefined glycoprotein. Some neurons in sensory nuclei of the brainstem exhibited a similar constituent on their surfaces. Retinal rod outer segments and the cerebellar granular layer possessed masked glucuronyl 3-SO4 that became immunopositive after digestion with chondroitinase ABC and that occurred in chondroitin 6-SO4 and chondroitin 4-SO4, respectively. The surface of neurons in the eighth nerve root and in neighboring nodes of Ranvier stained for unmasked glucuronic acid 3-SO4 and chondroitin 6-SO4. Some neurons of the cerebral cortex expressed unmasked glucuronyl 3-SO4, chondroitin 6-SO4, and terminal alpha GalNAc on their surfaces. Certain cortical neurons and nerve tracts with chondroitin 6-SO4 and terminal alpha GalNAc lacked glucuronyl 3-SO4, and other neurons possessing chondroitin 6-SO4 failed to express either glucuronyl 3-SO4 or terminal alpha GalNAc. Lability of lectin affinity to hyaluronidase suggested the presence of terminal alpha GalNAc in the chondroitin 6-SO4 on cortical neurons. The findings document further the heterogeneity of neural glycoconjugates, expand knowledge about the diversity of neurons with respect to their content of partially characterized glycoconjugates, and link glucuronyl 3-SO4 with or without chondroitin 6-SO4 spatially to sites of active Na+ transport in sensory nerves.

Animals↗

PubMed1996

Focal expression of A-CAM on pillar cells during formation of Corti's tunnel in gerbil cochlea.

BACKGROUND: The organ of Corti in the mammalian cochlea develops from a simple epithelium into a complex structure consisting of as many as ten highly specialized cell types. The purpose of the present study was to examine the possible role of a cell adhesion specific molecule (A-CAM) in mediating morphogenesis of the organ of Corti. METHOD: The expression of A-CAM was studied in a series of inner ears collected from neonatal gerbils at two days intervals from 0 to twenty days after birth. Immunostaining was performed with a mouse monoclonal antibody raised against A-CAM isolated from chicken cardiac muscle. RESULTS: The adhesion molecule appeared just prior to opening of the tunnel of Corti and disappeared after full expansion of tunnel space. A-CAM was detected in the basal turn of the cochlea as early as two days after birth and its expression moved progressively toward the apex of the cochlear spiral. It was observed in all three cochlear turns at eight days after birth but disappeared after postnatal day twelve. Immunostaining for A-CAM was localized only to the region where inner and outer pillar cells separate to form the tunnel of Corti. CONCLUSIONS: A-CAM apparently plays a role in the formation of the tunnel space by modulating apical adhesion above the separation between inner and outer pillar cells.

Age Factors↗

PubMed1996

Stage-specific expression of fuco-neolacto- (Lewis X) and ganglio-series neutral glycosphingolipids during brain development: characterization of Lewis X and related glycosphingolipids in bovine, human and rat brain.

We have purified and characterized a bovine brain pentaglycosylceramide as Lewis X and identified it in human and rat brain using anti-Lewis X (anti-SSEA 1) monoclonal antibody. Neutral glycosphingolipid expression in developing rat brain has been examined by digoxigenin immunostaining and TLC-immunostaining using anti-SSEA 1 and anti-GgOse4Cer (GA1) monoclonal antibodies. Five transient Lewis X-series bands were identified in brain at embryonic day 15 that disappear by postnatal day 5 (one disappears at embryonic day 18). Gangliotetraosylceramide (GA1) first appears at embryonic day 21 and increases in concentration with age until postnatal day 21. In addition, we have purified another minor brain neutral glycosphingolipid and tentatively identified it as a Lewis X-series glycolipid by gas chromatography-mass spectrometry analysis followed by TLC-immunostaining with anti-SSEA 1 antibody.

Aging↗

PubMed1996

Localization of actin in basal cells of stria vascularis.

The distribution of actin in the lateral wall of the cochlear duct was investigated in the gerbil, rat, mouse and hamster. A monoclonal antibody specific for muscle alpha and gamma actins, and a polyclonal antiserum reactive with smooth muscle gamma and non-muscle beta actins yielded strong immunostaining of basal cells in the stria vascularis and of smooth muscle cells in lateral wall blood vessels. Both cell types stained in all four genera. Diffuse cytosolic staining was observed along the full-length of the basal cell layer including the blunt cell processes which they extend toward strial marginal cells. Immunoreactive basal cells appeared continuous with morphologically similar cells investing vessels penetrating the stria from the spiral ligament. The basal cells failed to bind antibodies to smooth muscle alpha actin and sarcomeric actin. By electron microscopic immunocytochemistry, gold labeling for actin was observed on dense, fine fibrils in the cytoplasm of the basal cells. In paraffin sections adjacent to those stained for actin, antibody to vimentin stained intermediate and basal cells in the stria vascularis whereas antibody to isoform 1 of the facilitated glucose transporter protein family (GLUT1) labeled only the non-overlapping apical and basal plasmalemma of basal cells. Content of vimentin, GLUT1 and muscle gamma actin supports the derivation of basal cells from mesoderm. The presence of stress fibers containing muscle gamma actin points to a possible contractile activity of basal cells which conceivably could be related to transport of K+ to and within the intrastrial compartment or regulation of blood flow in the stria vascularis.

Actins↗

PubMed1996

The fine structure of spiral ligament cells relates to ion return to the stria and varies with place-frequency.

Ultrastructural analysis of cells in the cochlea's lateral wall was undertaken to investigate morophologic features relevant to the route of K+ cycling from organ of Corti (OC) to stria vascularis (StV) and to the question of a transcellular versus an extracellular path. The fine structure of outer sulcus cells (OSCs) evidenced their capacity for uptake of K+ from Claudius cells and from perilymph in inferior spiral ligament. Plasmalemmal amplification and mitochondrial density together with known content of Na,K-ATPase testified to activity of type II, IV and V fibrocytes in resorbing K+. Location and fine structure afforded a basis for distinguishing subtypes among the type I, II and IV cells. The type II, IV and V fibrocytes can be viewed as drawing K+ from surrounding perilymph and from OSCs and generating an intracellular downhill diffusion gradient for K+ flow through gap junctions to subtype Ib and Ia fibrocytes and strial basal cells. Pumping action enabled by extreme structural specialization of type II fibrocytes is considered to mediate K+ translocation across the interruption between the gap junction connected epithelial and gap junction connected fibrocyte systems and to explain ion flow directed toward StV through OSCs and fibrocytes despite their lack of polarity. The OSC bodies shrank, their root bundles expanded and the gap junction contact between OSCs and Claudius cells increased toward the base of the cochlea. Expanding root bundles and type I and IIb fibrocyte populations contrasted with shrinking OHCs and Deiters and tectal cells from the apex to the base of the cochlea. These differences indicated an increased magnitude and alternate route of K+ transport toward the StV in high as compared to low-frequency regions. The augmented K+ transport through spiral ligament in basal cochlea correlates with and provides a possible basis for the larger endocochlear potential in the base. The findings appear consistent with current flow extracellularly through scalae tympani and vestibuli and transcellularly through OC, OSCs and class I, II, IV and V fibrocytes.

Acoustic Stimulation↗

PubMed1995

Postnatal expression of the facilitated glucose transporter, GLUT 5, in gerbil outer hair cells.

The fifth isoform from the family of facilitative glucose transporters (GLUT 5) was identified in the gerbil cochlea by light and electron microscopic immunohistochemistry. The immunostaining procedure employed a polyclonal antibody raised against a synthetic peptide representing the carboxy terminus of human GLUT 5. Immunoreactive GLUT 5 was abundant in the basolateral plasma membrane of outer hair cells (OHCs) in the mature gerbil cochlea. No immunostaining was observed in any other site in the cochlea or vestibular system. During postnatal development of the gerbil inner ear, OHCs were first observed to express GLUT 5 in a punctate pattern at 10 days after birth. Immunostaining intensity increased gradually and developed a linear pattern along the entire OHC basolateral plasmalemma between 10 and 16 days after birth when it approached adult levels. The developmental expression of GLUT 5 corresponded with the appearance of glycogen in OHCs and structural maturation of the organ of Corti. This time period also coincided with the onset and rapid maturation of auditory function in the gerbil. GLUT 5 apparently supports OHC function by facilitating uptake of glucose which enables these cells to sustain a high level of metabolic activity in a relatively anaerobic environment.

Animals↗

PubMed1995

Cytological changes related to maturation of the organ of Corti and opening of Corti's tunnel.

Maturation of the organ of Corti in the gerbil was analyzed between 2 and 16 days after birth (DAB) by electron microscopy and immunostaining for beta-tubulin. At 2 DAB, the organ of Corti consisted of stratified epithelium bearing immature sensory hair cells (HCs) and supporting cells. Maturation of OHCs and Deiters cells progressed in a medial-to-lateral direction and cytoskeletal development in inner pillar cells preceded that in outer pillar cells at the single location studied along the frequency-place map. Pillar cell differentiation progressed through a unique stage characterized by the appearance and stratification of structural features apparently concerned with opening of Corti's tunnel and subsequently showed other structural changes related to maturity toward the adult form. Development of the microtubule cytoskeleton occurred first in the cell's apex and proceeded basally. Ruffling of a middle region of the cell surface by microvilli appeared to promote separation between inner and outer pillar cells and initiate tunnel opening at 4 DAB. Proliferation of distended cisternae of granular reticulum evidenced proteinaceous secretion by these cells between 4 and 8 DAB. Subsequent tunnel expansion at about 14 DAB coincided with appearance in outer pillar cells of tubulocisternal endoplasmic reticulum and associated Golgi complexes that are thought to mediate fluid and ion secretion. Sixteen days postnatally after disappearance of granular and tubulocisternal reticula and Golgi complexes and at the time of clearing of tunnel fluid, lysosomes interpreted as mediating catabolism of endocytosed protein congregated beneath the apical and apicolateral plasmalemmae of inner pillar cells. As with pillar cells, development of the microtubule system in Deiters cells proceeded from the cell's apex to base. Following differentiation of their microtubule system by 8 DAB, Deiters cells showed expansion of Golgi cisternae between 10 and 15 DAB and development of tubulocisternal endoplasmic reticulum at 15 DAB. Hair cells possessed abundant, distinctively large mitochondria from 4 to 10 DAB. The subsurface cisternae matured earlier in medial as opposed to lateral outer hair cells. Vesicles budding from underlying cisternae appeared associated with development of subsurface cisternae and at 16 DAB were still observed in third row but not in more mature first row HCs.

Animals↗

PubMed1995

The rosette complex in gerbil Deiters cells contains gamma actin.

The relationship of selected cytoskeletal elements with the rosette complex of Deiters cells was examined immunocytochemically in the gerbil cochlea. By light microscopy, the staining pattern for actin in the apical portion of Deiters cells corresponded with the location of the rosette complex. At the ultrastructural level, the actin antibodies bound selectively at the periphery of the dense trabeculae in the center of the complex. Comparative staining with a battery of polyclonal and isoform-specific monoclonal antibodies revealed selective presence of the gamma muscle actin isoform in this location. The loose meshwork at the periphery of the rosette complex stained selectively with a monoclonal antibody to vimentin. beta-tubulin was not associated with the rosette complex but occurred in abundance in the microtubule-rich stalk. Actin and vimentin were not detected in the apical compartment of Deiters cells at the extreme base of the cochlea, thus confirming their association with the rosette complex which is not present in regions of the gerbil cochlea tuned to frequencies of 20 kHz or higher (Spicer and Schulte, 1993, 1994). The cytoarchitecture of the rosette complex and its preferential distribution along the place-frequency map promote speculation that Deiters cells may play a role in regulating ion homeostasis and/or micromechanical response properties of the organ of Corti.

Actins↗

PubMed1995

Biodistribution and radioimmunopharmacokinetics of 131I-Ama monoclonal antibody in atherosclerotic rabbits.

Monoclonal antibodies have been raised against Ama isolated from human and experimental atherosclerotic plaque. 131I-Ama-MoAb in the whole antibody form was injected into normal NZW rabbits and Watanabe hyperlipidemic rabbits. Biodistribution studies showed that atheromatous aortas had a significantly higher (5-7X) uptake of 131I-Ama-MoAb than that of normal aortas. However, 131I-Ama-MoAb was cleared very slowly from atherosclerotic rabbits. As a result, atheromas could not be identified by imaging because of the low target to non-target ratios.

Animals↗

PubMed1995

Ultrastructural localization of Na,K-ATPase in the gerbil cochlea.

The transport enzyme Na,K-ATPase has been localized to several different cell types within the inner ear by enzyme cytochemistry, immunohistochemistry, and in situ hybridization. Although these histochemical procedures have provided a fairly consistent pattern of the enzyme's distribution, the precise location of Na,K-ATPase in the cell membrane of some polarized and non-polarized cell types remains uncertain. We addressed this problem in the gerbil cochlea using electron microscopic immunogold cytochemistry. The results confirmed prior ultrastructural localization of Na,K-ATPase along the basolateral plasma membrane of strial marginal and outer sulcus epithelial cells but differed from a previous report in failing to detect the enzyme at the surface of strial intermediate cells. The findings also concurred with and extended previous work in showing immunogold labeling along the entire cell membrane of non-polarized Type II fibrocytes in the inferior portion of the spiral ligament and of subpopulations of fibrocytes in the suprastrial and supralimbal regions. Our observations agreed further with light microscopic immunostaining in displaying uniform gold labeling for Na,K-ATPase in the neurilemma of Type I spiral ganglion neurons, even though these cells are completely ensheathed by myelin. Surprisingly, the enzyme was detectable in the neurilemma of afferent but not that of efferent nerve processes beneath hair cells.

Animals↗