bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fine structure of hepatic sinusoids and sinusoidal cells in disease
Authors: Le Bail B. , Bioulac‐Sage P. , Senuita R. , Quinton A. , Saric J. , Balabaud C. 
Published: February 2005

AbstractLiver sinusoids are special capillaries that are limited by fenestrated endothelial cells, without a genuine basement membrane, surrounded by perisinusoidal cells storing vitamin A, and harbouring Kupffer cells and pit cells, resident macrophages, and large granular lymphocytes, respectively. Each nonparenchymal cell and parenchymal cell of the liver interacts with all others and with the extracellular matrix. Therefore, the functional ability of each cell is constantly being modified by the metabolic activity of the others.Human liver biopsies (132), needle or surgical, perfusion‐fixed with glutaraldehyde and processed for transmission electron microscopy (TEM), and occasionally for scanning electron microscopy (SEM), were examined. The study included liver diseases (such as alcoholic liver diseases, benign and malignant liver tumors, cholestasis of various origins, fulminant hepatitis, acute rejection after orthotopic liver transplantation, Budd‐Chiari syndrome), as well as general or extrahepatic diseases (such as diabetes, hemochromatosis, hypervitaminosis A, various hematological disorders), and normal controls.Ultrastructural abnormalities are described and illustrated under two different headings: (1) elementary lesions of sinusoidal cells (endothelial, Kupffer, perisinusoidal and pit cells), nonsinusoidal cells (in the space of Disse and/or in the lumen), the extracellular matrix; and (2) the major pathological entities including perisinusoidal fibrosis, capillarization of sinusoids, sinusoidal dilatation, and peliosis. In the discussion, an overview of the major abnormalities reported in the literature is presented, and some specific questions regarding (1) perisinusoidal fibrosis in liver with normal histology, (2) the overload of perisinusoidal cells with lipids in non‐hypervitaminosis A intoxication and (3) the etiological relationship of sinusoidal dilatation, peliosis, perisinusoidal fibrosis, or sinusoidal tumors with drugs and toxic compounds are discussed. In the event that lesions are not specific to any diagnosis, the knowledge of the ultrastructure of sinusoids is extremely useful from the perspective of the liver as an ecosystem.
Lanthanum probing of cell membrane permeability in the rat heart: Pathological versus artefactual alterations
Authors: Harper I. S. , Williams K. , Lochner A. 
Published: February 2005

AbstractThe influence of fixation on membrane permeability has been examined in the isolated rat heart using lanthanum as a permeability probe. Normal and ischaemic hearts were probed at various stages during a conventional fixation programme with either ionic or colloidal lanthanum and compared with lanthanum saline administered prior to fixation. Fixation of the myocardium coincident with or followed by lanthanum probing resulted in an influx of the probe into most myocytes in normal tissue. Alterations in permeability after ischaemic episodes could not be distinguished from this artefact. However, lanthanum saline prior to fixation showed exclusion of the probe from normal tissue, while the increased permeability demonstrated after ischaemia was associated with declining myocardial performance during subsequent reperfusion. These results illustrate the need for caution in the application and evaluation of methods determining permeability in fixed tissue. Probes of differing size and charge permeated fixed tissue to varying degrees thereby implicating the formation of specific lesions during chemical fixation.
Comparison of osmium/sonication and edta/sonication microdissection techniques in exposing the adepithelial basal lamina surface of developing rat colon
Authors: McCarthy Kevin J. , Kaye Gordon I. 
Published: February 2005

AbstractWe have used two epithelial‐stripping techniques in our studies of the basal lamina in the developing rat colon. The first involves prolonged osmication followed by sonication; the second uses chelation of calcium by EDTA followed by sonication. Both techniques remove the epithelium from the basal lamina; however, the EDTA/sonication technique appears to produce a cleaner adepithelial surface of the basal lamina. In addition, the fine structure of the basal lamina appears to be better preserved in specimens prepared by the EDTA/sonication technique. In contrast, the basal lamina of specimens prepared by the osmium/sonication technique has a shattered appearance that we believe is due to an increase in the fragility of the delicate fetal basal lamina.
Monoamine synaptic structure and localization in the central nervous system
Authors: Maley Bruce E. , Engle Mary Gail , Humphreys Suzanne , Vascik Debra A. , Howes Kimberly A. , Newton Bruce W. , Elde Robert P. 
Published: February 2005

AbstractThe monoamines dopamine, noradrenaline, adrenaline, and serotonin as well as the diamine histamine have a widespread distribution in the central nervous system within synaptic terminals and nonsynaptic varicosities. In certain regions of the central nervous system the monoamines are contained in varicosities that have no synaptic specialization associated with them, suggesting a possible neuromodulatory role for some of the monoamines. The majority of monoamine labelled structures are synaptic terminals which are characterized by the presence of small, clear vesicles (40–60 nm) and large, granular vesicles (70–120 nm) within the terminal. A third population of vesicles—small, granular vesicles—which are visible only after histochemical staining, are probably the equivalent of the small, clear vesicles present after either autoradiographic or immunohistochemical labelling. Most monoamine containing terminals contact dendrites and dendritic spines and, less frequently, neuronal somata and other axons. Both asymmetrical and symmetrical membrane specializations are associated with monoaminergic terminals; however, asymmetrical contacts are the most frequent type found. These ultrastructural results indicate that monoamine containing terminals and varicosities in general share many common morphological features, but still have diverse functions.
Freeze‐fracture organization of hair cell synapses in the sensory epithelium of guinea pig organ of Corti
Authors: Saito Kogaku 
Published: February 2005

AbstractThe fine structure of both the afferent and efferent hair cell synapses in the sensory epithelium of guinea pig organ of Corti was examined by freeze‐fracture electron microscopy. In the afferent synapse, barlike aggregates of intramembrane particles (IMPs) of about 10 nm in diameter were seen on the P‐face of the afferent presynaptic membrane directly beneath the presynaptic dense projection which is located in the active zone of the presynaptic membrane. Small and large depressions have been seen on the presynaptic membrane. The former were observed in the proximity of the barlike aggregates, while the latter were observed some distance from the aggregate. In outer hair cells, IMPs of about 10 nm in diameter were seen on the P‐face of the afferent postsynaptic membrane at a density of 3,000/μm2.In the efferent synapse, many aggregates composed of from several to tens of large IMPs of 13 nm in diameter were observed on the presynaptic membrane. These aggregates were localized to small membrane depressions, which tended to be deeper as particle number per aggregate increased.Dense populations of IMPs of about 9 nm in diameter were observed on the P‐face of the efferent postsynaptic membrane at a density of 4,000/μm2. A fenestrated subsynaptic cistern completely covers the efferent postsynaptic membrane. Moreover, the subsynaptic cistern spans several efferent postsynaptic membranes when efferent synapses are gathered in a group.In the afferent and efferent synapses of hair cells, specializations of the synaptic membranes were represented by marked aggregates characteristic of IMPs. In the efferent synapse, IMP movement inside the synaptic membrane was proposed in relationship to retrival of synaptic vesicle membrane. Structural relationship between the subsynaptic cistern and efferent postsynaptic membrane was revealed.
High resolution scanning electron microscopy of stereocilia in the cochlea of normal, postmortem, and drug‐treated guinea pigs
Authors: Osborne Michael P. , Comis Spiro D. 
Published: February 2005

AbstractThe morphology of hair bundles has been studied by high resolution scanning electron microscopy using a variety of fixatives, including glutaraldehyde, glutaraldehyde‐picrate, glutaraldehyde‐tannic acid, glutaraldehyde followed by post‐fixation in osmium tetroxide, and the osmium thiocarbohydrazide technique. Critical evaluation of several metal coatings, gold, gold‐palladium, and platinum has been carried out.Both the surface texture of stereocilia and their cross‐links are sensitive to fixation and metal coating. We are of the opinion that glutaraldehyde gives the best general quality of fixation and preservation for all types of cross‐links. We have described three major sets of cross‐links: first, lateral links connecting stereocilia within the same row; second, lateral links connecting stereocilia of adjacent rows; and third, upward‐pointing links, one per stereocilium, connecting the tip of each shorter stereocilium to the lateral surface of the adjacent taller stereocilium. Current physiological and anatomical evidence suggests that the lateral links couple the individual stereocilia within the hair bundle so that they function as a single mechanical unit. The upward‐pointing tip links are ideally placed to respond to mechanical deformation of the hair bundle, being stretched when the stereocilia are deflected in the excitatory direction towards the tallest row and relaxed when deflected in the opposite, inhibitory direction.Postmortem morphological changes are detected within 15 minutes of cardiac arrest and become progressively more pronounced in time. These results enabled us to distinguish specific druginduced changes which could not be attributed simply to cell death. Effects of cisplatin and kanamycin upon hair bundles are described. The work reported here is based on studies using the guinea pig cochlea. Some of the postmortem changes described have also been confirmed in human cochleas.It is stressed that many of the postmortem and drug‐induced effects can only reliably be studied by high resolution scanning electron microscopy coupled with appropriate prearation procedures.
Intracellular distribution of actin in cells of the orgen of Corti: A structural basis for cell shape and motility
Authors: Slepecky Norma B. , Hozza Mark J. , Cefaratti Lisa 
Published: February 2005

AbstractImmunofluorescence staining and phalloidin labeling have provided localization of actin in the sensory and supporting cells of the inner ear at the light microscopic level. However, with electron microscopy, neither actin nor actin filaments have been found in the outer hair cell body. This paper describes various techniques utilized to preserve and identify cytoplasmic actin at the ultrastructural level. Post‐embedding staining of Lowicryl K4M sections, pre‐embedding staining of permeabilized cells of the organ of Corti, pre‐embedding staining of vibratome sections, and pre‐embedding staining of permeabilized dissociated cells documented the presence of actin, but each of these techniques was best suited to localize actin in specific parts of the cell. Cytoplasmic actin was labeled when isolated cells were lightly fixed and membranes were permeabilized with detergent—conditions under which the cell ultrastructure was compromised. Under conditions of optimal fixation, cytoplasmic filaments embedded in the dense granular matrix of the hair cell cytoplasm were observed.
Analysis of neuronal networks: A review of techniques for labeling axonal projections
Authors: Ralston Henry J. 
Published: February 2005

AbstractIn order to analyze connections between neurons in the vetebrate central nervous system, methods have been developed to label a given population of axons of known origin so that they can be differentiated from other, non‐labeled structures. Three such methods are reviewed here: experimentally induced orthograde (Wallerian) degeneration, axon transport of radioactive proteins demonstrated by autoradiography, and axon transport of macromolecules that can be reacted histochemically to yield a visible reaction product. Each of the methods has particular strengths and weaknesses. Degeneration methods may differentiate between different functional classes of axons which have different fiber diameters. However, degeneration distorts the morphology of axon terminals, making them more difficult to interpret, and degenerating terminals may be removed rapidly by phagocytosis. Autoradiography of radioactive terminals preserves normal fine structure, but the necessary exposure times extend the method by weeks or months, and care must be exercised to distinguish labeled axons from other structures exhibiting background or transneuronal radioactivity. Histochemical methods, such as those used to demonstrate horseradish peroxidase conjugated to wheat germ lectin (WGA‐HRP), are sensitive and rapid, but the injection site must be carefully characterized, and the presence of transneuronal label may make interpretation of the results difficult.Experimental methods of axonal labeling have been invaluable in studying neuronal networks. Each of the methods described here may be of particular value, given the nature of the system to be analyzed.
Synaptic connections of neurones identified by Golgi impregnation: Characterization by immunocytochemical, enzyme histochemical, and degeneration methods
Authors: Somogyi Peter 
Published: February 2005

AbstractFor more than a century the Golgi method has been providing structural information about the organization of neuronal networks. Recent developments allow the extension of the method to the electron microscopic analysis of the afferent and efferent synaptic connections of identified, Golgi‐impregnated neurones. The introduction of degeneration, autoradiographic, enzyme histochemical, and immunocytochemical methods for the characterization of Golgi‐impregnated neurones and their pre‐and postsynaptic partners makes it possible to establish the origin and also the chemical composition of pre‐and postsynaptic elements. Furthermore, for a direct correlation of structure and function the synaptic interconnections between physiologically characterized, intracellularly HRP‐filled neurones and Golgi‐impregnated cells can be studied. It is thought that most of the neuronal communication takes place at the synaptic junction. In the enterprise of unravelling the circuits underlying the synaptic interactions, the Golgi technique continues to be a powerful tool of analysis.
Preparation of fetal rat brains for light and electron microscopy
Authors: Åström Karl E. , Webster Henry deF. 
Published: February 2005

AbstractTo study cellular shapes, growth patterns, and fine structure during early stages of CNS development in rat embryos, preparative procedures were evaluated and modified to meet two criteria: (1) Coronal semithin sections should reveal undeformed telencephalic hemispheres that were symmetrically expanded on both sides of midline structures and were surrounded by contiguous mesenchyme. (2) In electron micrographs, cells should have intact, undistorted surface membranes, evenly distributed nucleoplasm and well preserved cytoplasmic organelles. To meet these criteria, 378 fetuses with a gestational age of 11–20 days (E11–E20) were used to test and modify procedures for anesthesia, embryo removal and handling, dissection, fixation, dehydration, and embedding of the embryonic CNS. Most specimens were in an early stage of development (E11–E13), which, in case of the neopallial wall, is the preneural period. The tests produced methods that met the above criteria and identified the most common artifacts and their causes. Deformities of the cerebral hemispheres and separations between the brain and its coverings were usually caused by trauma during embryo removal and during handling before fixation. Changes in cellular volumes, especially swelling during fixation and dehydration, were the most important causes of histological artifacts. The procedures and methods that consistently produced the best light and electron microscopic preservation of the E11–E13 rat CNS are described. Fixation was best when the brains were treated with glutaraldehyde and s‐collidine buffer, followed by osmium tetroxide in s‐collidine buffer. A surprisingly beneficial effect of sodium chloride in the dehydrating alcohol was noted.
Fasting induces modifications of the endoplasmic reticulum in intestinal cells
Authors: McLeese Jennifer , Bergeron Michel 
Published: February 2005

AbstractThe polymorphism of the endoplasmic reticulum (ER) in epithelial cells with different transport functions such as the enterocyte suggests that the ER may be involved in some way in molecular transport. To further access this possibility, we examined the ER from the intestine of winter flounder, Pseudopleuronectes americanus, a species which undergoes an annual fast of approximately 6 months' duration, a time during which previous work indicates nutrient carrier number does not change. Fish from June (feeding) and January (8–10 weeks fasted) were sampled. Tissues from the pyloric caeca, foregut, midgut, and hindgut were prepared for electron microscopy using two techniques of staining. Cell height was unaltered in any section, although microvillar length shortened variably. Cellular organization, including position of nuclei, number and distribution of mitochondria, and presence of basolateral membranes, did not change. The ER appeared equally abundant in June and January. However, use of the osmium impregnation technique, which is specific for ER cisternal contents, revealed a change in the impregnation of ER, from a heavily impregnated network in summer to little or no impregnation in winter. These results suggest that a shift in function of the ER had occurred when nutrient transport ceased, and supports a role of the ER in nutrient transport.
Cellular and developmental biological aspects of bovine meiotic maturation, fertilization, and preimplantation embryogenesis in vitro
Authors: Van Blerkom Jonathan , Bell Hobart , Weipz Deborah 
Published: February 2005

AbstractCellular aspects of reinitiated meiosis, fertilization, and early preimplantation embryogenesis in the bovine species were examined under in vitro conditions. An analysis of the cytoplasmic distribution of mitochondria, lipid droplets and vesicles in over 5,000 living GV‐stage oocytes, with subsequent examination by electron microscopy, indicated that the organization of cytoplasm was pleomorphic and that five distinct cellular phenotypes could be identified. Inspection of oocytes during the resumption of arrested meiosis in vivo and in vitro demonstrated that the subcellular organization of the bovine oocyte cytoplasm remains unchanged during maturation to metaphase II. The influence of culture conditions and media on the frequency of maturation, cytoplasmic organization, fertilizability, and early preimplantation embryogenesis was also determined. The findings indicate that meiotic maturation and fertilization in the bovine species can occur at high frequency under comparatively simple and defined conditions. However, the acquisition of developmental competence for fertilization, and the ability of the egg to develop progressively after fertilization appears to be related to the organization of the cytoplasm at the GV stage. The relationship between cytoplasmic organization and conditions of maturation, fertilization, presence or absence of cumulus cells, and the acquisition of developmental competence is discussed with respect to (1) cell biological aspects of mammalian oocyte maturation, (2) the potential influence of extrinsic factors (e. g., differential intrafollicular biochemistry and morphophysiology) on sub‐cellular organization of the GV‐stage oocyte, and (3) the finding that morphologically equivalent bovine embryos derived from the in vitro fertilization of in vitro‐matured oocytes may be developmentally heterogeneous. The studies also revealed that nuclear and cytoplasmic aberrations which could preclude normal embryogenesis can develop shortly after fertilization. The significance of this finding with respect to cytoplasmic phenotype of the oocyte and conditions of maturation, fertilization, and early embryo culture is discussed.
Real space modulation in bi2Sr2CanCun+1O6+2n and TI2Ba2CuO6 Superconductors Derived From Electron Diffraction Information
Authors: Verwerft Marc , Tendeloo Gustaaf Van 
Published: February 2005

AbstractWe will try to illustrate here that, simply from the geometry of the electron diffraction pattern of an incommensurably modulated structure, conclusive information can be obtained on the real space shape of this modulation. The method applied here is based on the 3 + 1 dimensional description of symmetry operations and can be summarized as follows: (1) reconstruct the three‐dimensional reciprocal space geometry of the modulated structure from electron diffraction information along different zone axes; (2) deduce the complete Bravais type symbol of the four‐dimensional structure from the general reflection conditions; and (3) derive the modulation function for each atom type from the superspace symmetry elements which result from the information of both modulation and basic structure. This method will be applied here in short on the Bi2Sr2CanCun+1O6+2n structure, for which system the results are in agreement with the ones recently obtained from neutron diffraction. For Tl2Ba2CuO6 where no data from other diffraction techniques are available, a more complete calculation will be performed, in order to determine the shape of the displacement function for the different atom types; the results are in agreement with the observed High Resolution Electron Microscopy (HREM) images.
Microwave energy fixation of plant tissue: An alternative approach that provides excellent preservation of ultrastructure and antigenicity
Authors: Benhamou Nicole , Noel Sylvain , Grenier Jean , Asselin Alain 
Published: February 2005

AbstractImmunocytochemical techniques are confronted with the problem of obtaining adequate tissue preservation together with retention of protein antigenicity. Various methods, including freeze‐drying and freeze‐substitution, have been devised to circumvent this problem. In the present study, we report that microwave energy used in combination with low concentrations of glutaraldehyde (0.1%) and paraformaldehyde (2%) preserves the structural integrity of plant tissue and antigenicity of proteins. Tobacco leaf samples fixed in a time as brief as 15–20 s exhibited excellent preservation of fine structures. By contrast, specimens irradiated for shorter (5–10 s) or longer (30–40 s) periods showed poor morphological preservation. Microwave irradiation for 15–20 s was found useful for immobilizing large amounts of soluble antigens. The fast microwave fixation method was successfully used to preserve pathogenesis‐related (PR) proteins, which were subsequently localized by a postembedding immunogold procedure. In addition to soluble antigens, cellulose subunits and pectic substances, two major plant cell wall components, were found to be highly preserved in microwave‐irradiated tobacco plant tissue. The present study demonstrates that microwave fixation of plant tissue is a simple and inexpensive method that is easy to perform with commercially available microwave ovens. The incubation time for fixation is reduced from 2 h to 15–20 s without loss of fine structural details. This method will undoubtedly acquire increasing applicability and relevance in plant biology.