bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of spiral ganglion cells in mammalian cochlea
Authors: Romand M.‐R. , Romand R. 
Published: February 2005

AbstractThe development of the spiral ganglion in the cat, the rat, and the mouse was studied by electron microscopy, from fetal stages in the cat and from birth in the rodent. In the earliest stages, a single population of ganglion cells is present. Immature spiral ganglion neurons possess small perisomatic processes that seem to disappear with development, before the myelination ganglion cells are surrounded by one or two layers of Schwann cell processes. With maturation, the Schwann process increases in number around the perikaryon and its processes, which leads to the onset of myelination. The onset of myelination of the cell body processes is asynchronous. The perikaryon may be delayed in myelination by several days. Moreover, ganglion neurons from a given region of the cochlea do not myelinate simultaneously. The differentiation of two types of fibers in the intraganglionic spiral bundle and the first appearance of TII neurons occurs around birth in the cat and a few days after birth for the rat and the mouse. The distinction of TII cells is possible due to characteristic accumulation of neurofilamentous structures in the cytoplasm.
Freeze‐fracture and immunomorphological analysis of spiral ganglion cells
Authors: Anniko Matti , Thornell Lars‐Eric , Virtanen Ismo , Ramaekers Frans C. S. 
Published: February 2005

AbstractFreeze‐fracture analysis of adult spiral ganglion cells of CBA/CBA mice revealed two types of membrane specializations. Most cells (type I) had a smooth surface and were surrounded by Schwann cells. Type II spiral ganglion cells showed numerous membrane specializations with well‐delineated indentations similar to those previously found on hair cells adjacent to afferent and efferent nerve endings. Immunomorphological analysis (using well‐defined monoclonal antibodies directed against different subclasses of intermediate filament proteins) revealed a unique co‐expression of neurofilaments, vimentin and cytokeratins in spiral ganglion cells of 8‐to 22‐week human fetuses.
Comparison of demyelination and neural degeneration in spiral and Scarpa's ganglia of C57BL/6 mice
Authors: Cohen Glenn M. , Park Janie C. , Grasso Joseph S. 
Published: February 2005

AbstractSpiral and Scarpa's (vestibular) ganglia of female C57BL/6 mice, ranging in age from 1.5 to 32 months, were examined by light and electron microscopy. The spiral ganglia of C57BL/6 mice undergo sweeping neuronal losses. Based on cytological characteristics that repeat themselves in both young and old mice, we divided perikaryal demyelination and degeneration of spiral ganglia into four arbitary stages: (1) incipient demyelination, myelin sheaths begin to loosen and unravel; (2) contact, the partially demyelinated perikarya abut as the extracellular matrix disappear; (3) clumping, clusters of naked perikarya clump together, cytoplasmic processes surround the exterior of the clump; and (4) resorption, the clumps gradually disintegrate, leaving at completion large, fluid‐filled spaces and few cellular remnants. In Scarpa's ganglia, a small number of neurons demyelinate and clump, but none degenerate or undergo resorption.
Synaptic morphology of inner and outer hair cells of the human organ of Corti
Authors: Nadol Joseph B. 
Published: February 2005

AbstractInnervations of inner and outer hair cells of the organ of Corti of the human cochlea were studied by serial section electron microscopy. At the base of inner hair cells, presumed afferent fibers were of varying size and demonstrated synaptic specialization consisting of a presynaptic body, vesicles, and asymmetrical synaptic membrane specialization. Two types of neurons, vesiculated presumably efferent and nonvesiculated presumably afferent, synapsed at the base of outer hair cells. The synaptic specialization of afferent fibers included presynaptic body, vesicles, and asymmetrical membrane thickening, whereas efferent synapses demonstrated presynaptic vesicles and a subsynaptic cisterna. Some presumably afferent nerve terminals formed a reciprocal synapse with outer hair cells in both the human and the chimpanzee. Such a synaptic relationship demonstrated morphologic specialization consistent with both hair cell‐to‐neuron and neuron‐to‐hair cell transmission between the same outer hair cell and nerve terminal. The innervation density of inner and outer hair cells and the comparative anatomy of the afferent and efferent innervation are discussed.
Serial reconstruction of inner hair cell afferent innervation using semithick sections
Authors: Siegel Jonathan H. 
Published: February 2005

AbstractThe afferent innervation pattern of inner hair cells in the apex of the guinea pig cochlea was studied using serial reconstruction of semithick (0.25–μm) sections and high‐voltage electron microscopy (HVEM). This thickness produced a good compromise between the ability to resolve details of the synaptic contacts between the hair cells and sensory neurons and the number of sections required to reconstruct the nerve terminals within the receptor organ. The use of a goniometer allowed the sections to be tilted to angles optimum for viewing either the synaptic membrane specializations or the presynaptic bodies. Reasonably good images of 0.25‐μm sections could be obtained using a conventional 120‐keV microscope, but the images produced by the HVEM were clearly superior. The sensory nerve terminals and hair cells were reconstructed using a microcomputer‐based computer‐aided‐design system. Nerve terminals with complex shapes could be successfully rendered as surface models viewed as stereo pairs. The advantages and limitations of the techniques used are discussed.
Immunoelectron microscopic localization of neurotransmitters in the cochlea
Authors: Eybalin Michel , Altschuler Richard A. 
Published: February 2005

AbstractThis paper presents the works and methods of our respective laboratories using electron microscopic immunocytochemistry to identify and localize cochlear neurotransmitters. Antibodies to various prospective neurotransmitters and associated enzymes have been used to study the ultrastructural localization of several candidates for olivocochlear efferent neurotransmitters previously suggested by light microscopic immunocytochemistry. Antibodies against enkephalins label lateral olivocochlear efferent fibers. Antibodies against choline acetyltransferase (ChAT) (an enzyme marker for acetylcholine) label a major population of both lateral and medial efferent fibers and terminals, whereas antibodies to γ‐aminobutyric acid (GABA) label what might be a small subpopulation of both the lateral and medial efferent systems. The GABA‐like immunostained medial efferent fibers are preferentially located in the upper turns of the guinea pig cochlea, particularly the third turn. Immunoelectron microscopy shows that neither GABA nor ChAT immunolabels all medial efferent terminals, regardless of cochlear turn. All the different types of immunolabeled efferent terminals have been observed to make characteristic synaptic contacts; lateral efferent terminals on afferent dendrites and medial efferent terminals on outer hair cells and occasionally on type II afferent dendrites. Other types of contacts involving GABA‐like, and sometimes met‐enkephalin‐like, immunostained fibers are occasionally seen particularly in the upper turns of the cochlea. Immunoelectron microscopic results suggest that both medial and lateral efferent systems might be further subdivided on the basis of differences in neurotransmitters. Future trends of immunocytochemical research on cochlear neurotransmitters are proposed, particularly colocalization studies, which show a complex pattern of coexistence of neurotransmitters in the lateral efferent system.
Autoradiographic studies of selective amino acid uptake by neural and nonneural elements in the gerbil cochlea
Authors: Schwartz I. R. , Ryan A. F. 
Published: February 2005

AbstractThe cochlea is well suited for studies of the uptake properties of auditory neurons and nonneuronal supporting cells. Probe concentrations of radioisotopically labeled amino acids, including putative neurotransmitters and their precursors, breakdown products, and blockers, can be introduced via the natural, fluid‐filled channels of the inner ear. Uptake patterns can be mapped at cellular and intracellular levels using light and electron microscopic autoradiographic methods. The procedures for introduction of label, fixation, plastic embedment, and light and electron microscopic autoradiography are described with special reference to the cochlea. Labeling patterns observed with over 20 amino acids are summarized for hair cells, spiral ganglion neurons, efferents, and nonneural elements of the stria vascularis, limbus, and modiolus. Limitations on the interpretation of results and their implications for the general usefulness of the methods are discussed.
Synaptic circuitry identified by intracellular labeling with horseradish peroxidase
Authors: Hamos James E. 
Published: February 2005

AbstractDuring the past two decades new techniques have been developed to directly test the dogma that neuronal structure is correlated with neuronal function. In the earliest experiments, Procion yellow was injected into neurons after they had been characterized physiologically; these neurons were then viewed through the light microscope. Recent advances in the method generally employ horseradish peroxidase as the dye which is injected since it diffuses quite readily throughout the injected neuron and produces a stable reaction product for both light and electron microscopic studies. This review explores the utility of examining synaptic circuitry after physiologically recording from axons or neurons and then injecting horseradish peroxidase into them. As a model system, we studied the cat lateral geniculate nucleus and investigated, at the electron microscopic level, the synaptic contribution to this nucleus from retinogeniculate axons, from interneurons, and from the axon collaterals of neurons that project to visual cortex.
Scanning image detection (SID) system for conventional transmission electron microscope (CTEM) images
Authors: Tanji Takayoshi , Tomita Masahiro , Kobayashi Hiroyuki 
Published: February 2005

AbstractA new image detection system has been developed to display transmission electron microscope (TEM) images on a CRT without a video camera system. Deflection coils placed in both the upper space of an objective lens and in the lower space of the first intermediate lens scan a small electron probe simultaneously. The electrical signal acquired through an improved scintillator and a photomultiplier is synchronized with the scanning signal and displayed in a similar fashion to a conventional scanning TEM (STEM) instrument. A preliminary system using a 100 kV conventional TEM (CTEM) equipped with a hairpin‐type electron gun, produced an image with a spatial resolution of 1 nm.
On high‐resolution transmission electron microscopy in an unstable magnetic environment
Authors: Luzzi David E. 
Published: February 2005

AbstractOwing to the particular environment of the JEM4000EX HREM at the University of Pennsylvania, it became necessary to control the magnetic environment around the microscope. The unstable magnetic environment included two components, a slowly wandering vertical DC magnetic field and an AC magnetic field. The effects of these fields on the microscope performance were to introduce an uncertainty in the objective lens defocus value over a series of images and to reduce the attainable resolution of the microscope, respectively. A solution is presented in which these fields are stably reduced well within the limits of sensitivity of the JEOL, Ltd. JEM4000EX for high‐resolution imaging. This solution is based on a feedback loop using a pseudo‐Helmholtz coil to generate a well‐defined vertical magnetic field.
Lectin binding patterns to plasmalemmal glycoconjugates of goblet cells undergoing differentiation in vitro
Authors: Frisch Emily B. , Phillips Thomas E. 
Published: February 2005

AbstractThe plasmalemmal glycoconjugates of the HT29‐18N2 (N2) cell line were characterized on cells grown as (1) undifferentiated multilayers in glucose‐containing culture media and (2) monolayers of columnar cells acquiring the goblet cell phenotype in glucose‐free media. Lectins were unable to bind sheets of detached N2 cells in the absence of fixation. Following fixation with aldehydes, a dramatic unmasking of lectin binding sites was seen. When fixed monolayers were stained prior to embedding, biotinylated lectins, visualized by the avidin‐biotin‐complexed peroxidase technique, were more efficient than collodial gold‐coupled lectins. Lectin binding sites could also be detected by using collodial gold‐coupled lectins to stain monolayers embedded in LR White, Lowicryl K4M, and Lowicryl HM20. The binding of 5 lectins (wheat germ, Dolichos bifluros, peanut, soybean, and Ulex europeus) was found to be independent of the stage of differentiation; “pre‐differentiated” columnar cells which had prominent microvilli and no or few mucous secretory granules had identical staining patterns as well‐differentiated goblet cells with large numbers of secretory granules. Ricinus communis I was the only lectin whose binding was influenced by the stage of differentiation; it intensely labeled undifferentiated multilayers of N2 cells but only weakly labeled basolateral membranes of differentiated monolayers. Canavalia ensiformas (ConA) caused a moderate and even labeling of both apical and basolateral membranes of fixed monolayers stained prior to embedding, but post‐embedding labeling revealed heavy labeling along the lateral margins of all columnar cells and weak to moderate binding along the apical and basal cell surface.
A Stopped‐flow/rapid‐freezing machine with millisecond time resolution to prepare intermediates in biochemical reactions for electron microscopy
Authors: Pollard Thomas D. , Maupin Pamela , Sinard John , Huxley Hugh E. 
Published: February 2005

AbstractWe have developed an instrument capable of freezing transient intermediates in rapid biochemical reactions for subsequent freeze‐fracturing, replication, and viewing by transmission electron microscopy. The machine combines a rapid mixing unit similar to one widely used in chemical kinetics (Johnson, 1986) with a propane jet freezing unit previously used to prepare static samples for freeze‐fracturing (Gilkey and Staehelin, 1986). The key element in the system is a unique thin‐walled flow cell of copper that allows for injection and aging of the sample, followed by rapid freezing. During freeze‐fracturing, a tangential cut is made along the wall of the flow cell to expose the sample for etching and replication. The dead time required for mixing and injection of the reactants into the flow cell is less than 5 ms. Electronic controls allow one to specify, on a millisecond time scale, any time above 5 ms between initiation of the reaction and quenching by rapid freezing.
Ultrastructural aspects of oogenesis and oocyte growth in fish and amphibians
Authors: Wallace Robin A. , Selman Kelly 
Published: February 2005

AbstractOogenesis, the early events of primary oocyte growth (meiotic arrest, synapsis, ribosomal gene duplication), and folliculogenesis can be seen to particular advantage in the germinal ridge of the syngnathan ovary. After budding off the germinal ridge (a compartment of the luminal epithelium), nascent follicles then enter into a linear array of developing follicles within which temporal and stage‐specific events can be correlated with spatial distribution. Prominent features of the later phase of primary oocyte growth include intense transcriptional activity and the formation and subsequent dispersal of the Balbiani vitelline body (mitochondrial cloud) concomitant with an increase in cytoplasmic organelles and volume. Further oocyte growth is characterized by a period of cortical alveolus (in teleosts) or cortical granule (in anurans) formation, in which Golgi elements play a predominant role, and finally vitellogenesis. The latter process, which is responsible for the preponderance of oocyte growth, includes the hepatic synthesis and secretion of vitellogenin (VTG), the uptake of VTG from the bloodstream into the oocyte by receptor‐mediated endocytosis, and the transport of VTG via endosomes and multivesicular bodies to forming yolk platelets. In the process, VTG is proteolytically cleaved into the yolk proteins, which assume either a monoclinic (in cyclostomes) or orthorhombic (in teleosts and amphibians) crystalline array. Other structures associated with the growing oocyte are also briefly discussed, including nuage, the vitelline envelope, intercellular junctions between the oocyte and overlying follicle cells, pigment, intramitochondrial crystals in ranidae, and annulate lamellae.
Transmission electron microscopic X‐ray quantitative analysis of human dentin at 200 kV accelerating voltage
Authors: Yonehara Katsuhisa , Shinohara Minoru , Kanaya Koichi 
Published: February 2005

AbstractQualitative and quantitative x‐ray energy dispersive spectroscopy is now used successfully to analyze many features and processes in inorganic samples. When applied to inorganic samples, however, the results are often less satisfactory due to problems of preparation of organic samples, difficulty of measuring x‐rays from organic samples, damage of the sample by the electron beam, and other practical problems.In the present study we used a high voltage transmission electron microscope equipped with an energy dispersive x‐ray spectrometer to examine accurate quantitative standardless analysis of thin sections of an organic sample, human dentin.Based on our experiments we found the important parameters for quantitative analysis were sample thickness and appropriate choice of model sample. Further, we show that the method of Cliff and Lorimer can be used with biological samples at 200 kV, and we show that quantitative analysis of human dentin can be carried out at 200 kV. Finally, we show that areas of human dentin can be differentiated by their morphological characteristics and x‐ray analyses obtained in the transmission electron microscope.
Modified embedding procedure for microtomy of large particle zeolites
Authors: Ulan J. G. , Schooley C. , Gronsky R. 
Published: February 2005

AbstractA method is described to strengthen the binding of organic resin to inorganic zeolite, allowing large particles to be microtomed. For FeZSM‐5 aggregates the particle size limit increased from 3 μm to greater than 20 μm in diameter by application of this method. This technique can be applied to a variety of oxide powder samples, extending the utility of microtomy as a materials science tool.
Perspectives on golgi apparatus form and function
Authors: Mollenhauer Hilton H. , Morré D. James 
Published: February 2005

AbstractIn 1898, Camillio Golgi reported a new cellular constituent with the form of an extensive intracellular network (the apparato reticolare interno), which now bears his name. However, the history of Golgi's apparatus is replete with controversy regarding its reality, what components of the cell should be included under its aegis, and what terminology should be used when referring to it. Electron microscopy has resolved many of these controversies and it is appropriate that this volume emphasize that aspect of Golgi apparatus discovery.The principal structural component of the Golgi apparatus is the stack of cisternae, or dictyosome. As determined both biochemically and at the level of electron microscopy, the dictyosome is a highly ordered and polarized structure. The maintenance of order within the stack is thought to result from either intercisternal bonding constituents, or filamentous structures (or both) that bridge the space between adjacent cisternae.Mechanisms proposed for movement of membrane and product into and out of the dictyosome (i.e., the Golgi apparatus stack) include a serial mode which functions exclusively by the formation, displacement, and loss of cisternae from the stack, and a parallel mode which functions exclusively by the movement of membrane, product, or precursor molecules directly into the peripheral edges of the cisternae. In the parallel mode, all cisternae can be accessed either singly or simultaneously, at least in theory, at any position within the stack. It is probable that both the serial and the parallel modes function concomitantly and need not be mutually exclusive.Finally, the peripheral tubules of the cisternae represent a major membranous constituent of the cell with potentially unique functions. These tubules interconnect cisternae of adjacent stacks and may represent the major site of receptors for the shuttle (i.e., parallel) type of transfer among cisternae. Peripheral tubules as extensions of the cisternal lumina into the cytoplasm presumably have other functions, but these, like the tubules themselves, have only rarely been accommodated into functional models of Golgi apparatus dynamics in secretion or membrane flow.
Cytochemical characteristics of the golgi apparatus
Authors: Pavelka Margit , Ellinger Adolf 
Published: February 2005

AbstractLectinocytochemistry provides a useful tool for localizing subcompartments of the complex reticular apparatus of Golgi. The technique is based on interactions of lectins with glycoconjugates present in the limiting membranes and luminal spaces of Golgi elements. Application of a series of lectins of different sugar specificities permits a differentiation between Golgi subcompartments containing glycoconjugates with different oligosaccharide side chains. These may be (a) different glycoconjugates or (b) glycoconjugates at different stages during synthesis or repair of their glycans. The lectinocytochemical studies with mannose‐, glucose‐, N‐acetyl‐glucosamine‐, N‐acetylgalactosamine‐, galactose‐, fucose‐, and sialic acid‐recognizing lectins revealed predominating patterns that labeled distinct, i.e., cis, medial, trans, and transmost, regions of the Golgi apparatus. A further refinement could be achieved by differential lectin‐inhibition that enables a dissection of lectin binding reactions on the basis of their binding affinities. High‐affinity binding reactions showed that subcompartments are not necessarily confined to one single Golgi subregion and may change their position from one to another subregion. Some of the patterns observed may be interpreted in relation to certain steps during synthesis and modifications of glycans.