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  • 1995-1999  (38)
  • 1980-1984
  • 1999  (38)
  • Ultrastructure
  • Nuclear reactions
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  • 1995-1999  (38)
  • 1980-1984
Year
  • 1
    ISSN: 1432-041X
    Keywords: Key words Imaginal disc ; Axonal trajectories ; Ultrastructure ; Chaoborus (Insecta ; Diptera)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In one of his classical studies on insect metamorphosis, Weismann compared the imaginal anlagen of the ancestral phantom midge, Chaoborus, with those of advanced brachycerans. We have expanded his findings on the relationships between larval and imaginal organs using electron microscopy and cobalt backfilling of the antenna and leg anlagen and the axonal trajectories of corresponding larval sensilla. We show that both primordia are confluent with the larval antennae and ”leg” sensilla (an ancestral Keilin organ), respectively. These fully developed larval organs represent the distal tips of the imaginal anlagen rather than separate cell clusters. The axons of the larval antenna and leg sensilla project across the corresponding anlagen to their target neuromeres within the central nervous system (CNS). Within the discs, nerves composed of these larval axons, developing afferent fibres and efferences ascending from the CNS are found. Both the structure of the primordia and the axonal trajectories thus relate the situation found in advanced brachycerans with that seen in more ancestral insects. In addition, the larval antennae, legs, wings and even the eyes possess very similar afferent pioneer trajectories supporting the idea that the described pattern is generally used in the ontogeny of sensory systems.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 200 (1999), S. 81-90 
    ISSN: 1432-0568
    Keywords: Key words Elastic fibre system ; Microfibrils ; Collagen type IV ; Ultrastructure ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  This study deals with the examination of the elastic fibre system as well as collagen fibrils and collagen type IV in the amnion of the human chorionic plate of uncomplicated pregnancies at term. In organs other than placenta, the elastic fibre system comprises elastic fibres, elaunin and oxytalan microfibrils. The investigation was performed by light and electron microscopy and immunocytochemistry. Abundant oxytalan fibres were present in all amnionic layers, while no elastic fibres were found. Oxytalan microfibrils formed a broad subepithelial layer and were intermingled with collagen fibrils in the subjacent compact layer and in the amnionic mesoderm. Light microscopically, bunches containing orcein-stained oxytalan and collagen-type-IV-immunostained microfibrils were seen rising from the amnionic mesoderm perpendicularly towards the epithelial layer, where they obviously inserted. It can be assumed that the subepithelial microfibrillar layer and the following compact layer form an anchoring zone between the amnionic mesoderm and the epithelium that may contribute to the maintenance of strength. The ultrastructure of the bunches clearly showed collagen fibrils mixed with oxytalan microfibrils. No collagen type I-immunostaining was found in the bunches. After pretreatment of cryostat sections with elastase, oxytalan-orcein-staining was absent, but collagen type IV-immunoreactivity was not altered. Furthermore, after oxytalan-orcein-staining resp. anti-collagen type IV incubation, all positive fibres revealed an identical morphological pattern. We propose that oxytalan and collagen type IV may represent further members of the microfibril complex.
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  • 3
    ISSN: 1432-0568
    Keywords: Key words Intrinsic laryngeal motoneurons ; Cholera toxin HRP ; Ultrastructure ; Swallowing ; Respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The laryngeal motoneurons innervating the cricothyroid muscle (CT) are located in the semicompact formation just ventral to the rostral part of the compact formation of the nucleus ambiguus. The motoneurons innervating the posterior cricoarytenoid muscle (PCA) are located in the loose formation. We retrogradely labeled the CT and the PCA motoneurons using cholera toxin subunit B-conjugated horseradish peroxidase, and determined the ultrastructure and synaptic organization of these neurons. The CT and the PCA motoneurons had the appearance of α-motoneurons, i.e., large, oval or polygonal cells containing well-developed organelles and a prominent spherical nucleus. Two kinds of neurons were recognized among the PCA motoneurons. The one (PCA-A) was significantly smaller than the other (PCA-B). The average number of axosomatic terminals in a section was significantly largest in the PCA-B (56.6), smaller in the PCA-A (36.0), and smallest in the CT (32.3) neurons. Most of the axosomatic terminals (64.7%) contained pleomorphic vesicles and made symmetric synaptic contacts (Gray’s type II) with the PCA-A neurons, while more than 60% contained round vesicles with asymmetric synaptic contacts (Gray’s type I) in the CT (69.5%) and the PCA-B (60.6%) neurons. A few terminals associated with subsurface cisterns were present on all laryngeal motoneurons. These results indicated that the CT motoneurons may receive mostly excitatory terminals, whereas the PCA muscle may be regulated by neurons having many inhibitory terminals, and neurons having many excitatory terminals.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 199 (1999), S. 407-418 
    ISSN: 1432-0568
    Keywords: Key words Placenta ; Vascular wall ; Smooth muscle cell ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The vascular wall structure in the human full-term placental villi of normal pregnancy was studied by means of light and electron microscopy with an improved technique of perfusion fixation and tissue preparation. We observed 81 sections of stem villi that showed cross-sectional profiles of paired vessels in their center. Both vascular walls contained a large amount of extracellular matrix and no elastic lamina between smooth muscle cells of the media, making identification of the artery and the vein quite difficult at first sight. We then noted that the density of the smooth muscle cell population was always considerably higher in one than the other, and identified the former as artery and the latter as vein on the basis of their connection with larger arteries and veins running on the chorionic plate. Between the paired vessels, the artery had a smaller caliber than the vein, and the ratio of venous to arterial caliber was distributed from 1.0 to 2.5. The thickness of media was usually thicker in the vein than in the artery. Clusters of elastic fibers were found occasionally in the media of arteries and veins, and basement membrane-like materials were associated frequently with the elastic fibers and were distributed widely in the media as well as in the adventitia. In the veins, the smooth muscle cells of the most superficial part of the media contained well-developed rough endoplasmic reticulum and Golgi apparatus, indicating differentiation to secrete extracellular matrices. The present study revealed the difference of wall structure between arteries and veins in the placental stem villi for the first time at the ultrastructural level, and suggested differentiation of venous smooth muscle cells, possibly by some influence from the luminal side.
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  • 5
    ISSN: 1432-072X
    Keywords: Key wordsClostridium xylanolyticum ; Cinnamic acid ; Esterase ; Lignocellulose ; Sporogenesis ; Ultrastructure ; Cell envelope
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microorganisms that hydrolyse the ester linkages between phenolic acids and polysaccharides in plant cell walls are potential sources of enzymes for the degradation of lignocellulosic waste. An anaerobic, mesophilic, spore-forming, xylanolytic bacterium with high hydroxy cinnamic acid esterase activity was isolated from the gut of the grass-eating termite Tumilitermes pastinator. The bacterium was motile and rod-shaped, stained gram-positive, had an eight-layered cell envelope, and formed endospores. Phylogenetic analysis based on 16S rRNA indicated that the bacterium is closely related to Clostridium xylanolyticum and is grouped with polysaccharolytic strains of clostridia. A wide range of carbohydrates were fermented, and growth was stimulated by either xylan or cellobiose as substrates. The bacterium hydrolysed and then hydrogenated the hydroxy cinnamic acids (ferulic and p-coumaric acids), which are esterified to arabinoxylan in plant cell walls. Three cytoplasmic enzymes with hydroxy cinnamic acid esterase activity were identified using non-denaturing gel electrophoresis. This bacterium possesses an unusual multilayered cell envelope in which both leaflets of the cytoplasmic membrane, the peptidoglycan layer and the S layer are clearly discernible. The fate of all these components was easily followed throughout the endospore formation process. The peptidoglycan component persisted during the entire morphogenesis. It was seen to enter the septum and to pass with the engulfing membranes to surround the prespore. It eventually expanded to form the cortex, verification for the peptidoglycan origin of the cortex. Sporogenic vesicles, which are derived from the cell wall peptidoglycan, were associated with the engulfment process. Spore coat fragments appeared early, in stage II, though spore coat formation was not complete until after cortex formation.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 124 (1999), S. 89-99 
    ISSN: 1432-1106
    Keywords: Key words Microglial culture ; Brain macrophages ; Isolectin ; Ultrastructure ; Intracellular pathway
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The present study examined the lectin labeling of diverse morphological forms of microglia in culture. Similar to amoeboid microglial cells in vivo, polymorphic microglia showed lectin labeling at their plasma membranes, as well as in a few cytoplasmic vesicles and vacuoles. This labeling pattern was observed in cultured microglia incubated with isolectin at 4°C for 30 min. Five minutes after the temperature was raised to 37°C, the surface lectin receptors appeared to be internalized, as shown by the occurrence of many subsurface lectin-labeled vesicles, vacuoles and tubule-like structures. With longer incubation (up to 1–2 h at 37°C), many lysosomes and a few trans-Golgi saccules and associated lysosome-like structures became labeled. Concomitant with these changes was a reduction of lectin labeling at the plasma, with labeling having vanished in most of the cells after 1–2 h of incubation. By 24 h, only a few cells retained surface lectin labeling. It appears, therefore, that irrespective of morphology, lectin labeling (including its intracellular pathway) of microglia in culture parallels that of amoeboid microglia in vivo. This would offer a useful model for the study of lectin turnover in microglia and help to explain the roles of such receptors in microglial differentiation and function.
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  • 7
    ISSN: 1437-773X
    Keywords: Key words pHGF ; HGF ; Acute liver injury ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The protective effect of hepatocyte growth-promoting factor (pHGF) against CCl4-induced acute hepatitis in rats was examined by light and electron microscopy. Hepatocyte growth-promoting factor, purified from infant pig liver in an active form, has been used clinically in patients with hepatitis in China. Four hours after administration of CCl4, a single dose of pHGF was administered intraperitoneally. Six hours after administration of CCl4, inhibition of CCl4-induced hepatic necrosis and hepatocytes with severely dilated endoplasmic reticula were evident in rats treated with pHGF. At 48 h post administration, most hepatocytes had recovered, and not only mitotic hepatocytes (10–13 mitotic cells/100) but also mitotic Kupffer cells were observed. At 72 h, it was evident that the differentiation of hepatic stellate cells (Ito cell) into myofibroblast-like cells and the development of fibrosis around the central veins was prevented by pHGF. These results suggested that (1) pHGF may stabilize cell membranes, (2) pHGF acts as a mitogen not only for hepatocytes but also for Kupffer cells, and (3) pHGF prevents fibrogenesis in the case of CCl4-induced liver injury by preventing the differentiation of hepatic stellate cells.
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  • 8
    ISSN: 1437-773X
    Keywords: Key words Cerebral blood flow ; Blood–brain barrier ; Repeated brief cerebral ischemia ; Hippocampal CA1 ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Neuronal damage and changes in cerebral blood flow (CBF) and the permeability of the blood–brain barrier (BBB) following repeated brief periods of ischemia were studied in Mongolian gerbils. The cerebral ischemia was produced by three repeated occlusions of bilateral common carotid arteries for 3 min at 1-h intervals. CBF and permeability of the BBB were examined with tracers (China ink and silver nitrate) at 1, 3, and 7 days post ischemia using light and electron microscopy. Three days after the reperfusion, significant extravasation of tracers, consequential reduction of CBF, extensive neuronal destruction, and intravascular platelet aggregation were observed. Such vascular changes in the CA1 region were more severe than those in the frontal cortex. These findings strongly support the view that microcirculatory disturbance may be a mechanism responsible for delayed neuronal death in the CA1 region of the hippocampus.
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  • 9
    ISSN: 1437-773X
    Keywords: Key words: Secretory carcinoma ; Breast ; Intracytoplasmic lumina ; Immnohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a rare case of secretory carcinoma of the breast in a 50-year-old Japanese woman. The patient had been aware of a right breast tumor for 8 years, but had left it untreated. The tumor enlarged in size and became painful, and she visited our hospital. Breast carcinoma was diagnosed, and mastectomy was performed. Histopathological examination revealed features of a secretory carcinoma characterized by prominent secretory activity in the glandular and microcystic spaces, with some areas showing a follicular pattern resembling the thyroid gland. The secretory material was PAS-positive and immunohistochemically α-lactalbumin-positive. Ultrastructurally, the tumor cell contained many secretory vacuoles in the cytoplasm. In addition, extracellular and intracytoplasmic lumina were conspicuous; these were lined by microvilli projection and contained secretory material. By flow cytometric analysis, the DNA index was 1.14, which was diploid, showing relatively low proliferative activity.
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  • 10
    ISSN: 1437-773X
    Keywords: Key words KSHV ; HHV-8 ; TPA ; Ultrastructure ; Primary effusion lymphoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The ultrastructure of Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus-8 (HHV-8) has not yet been fully elucidated, although some findings have been reported using primary effusion lymphoma (PEL) cell lines, KS-1, harboring no Epstein–Barr virus (EBV) coinfection. In the present study, detailed fine structural examination of KSHV/HHV-8 was performed after stimulation of the PEL-derived cell line KS-1 with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) in vitro. While unstimulated KS-1 cells contained a small number of intranuclear virus particles associated with no extracellular mature particles, KS-1 cells stimulated with TPA produced many extracellular mature particles as well as intranuclear particles, in addition to interesting tubulo-reticular structures and aggregated tubular structures in vesicles. The induced intranuclear particles were empty, doughnut shaped, and dense cored, with outer and inner diameters of 100–110 nm and 60–70 nm, respectively. Dense-cored extracellular mature particles were 150–160 nm in diameter, and some contained doughnut-shaped cores, together with a few megaloviruses, 260 nm in outer diameter. These findings indicate that KS-1 cells treated with TPA can produce extracellular mature particles as well as intranuclear particles, which were proven to be KSHV/HHV-8.
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  • 11
    ISSN: 1437-773X
    Keywords: Key words Heart ; Ultrastructure ; Capillaries ; Endothelium ; Stereology ; Cardioplegic solutions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In open heart surgery and transplantation, sufficient structural preservation of the myocardium immediately following cardioplegic arrest is a precondition for overcoming ischemia and for resumption of postischemic function. Therefore, we compared the protective effect of three clinically applied cardioplegic solutions with fibrillating and beating hearts using structural criteria. Left ventricular samples were taken from (1) beating, or (2) fibrillating or arrested hearts following coronary perfu-sion with (3) St. Thomas' Hospital solution, (4) histidine tryptophane ketoglutalate (HTK) (Custodiol), or (5) University of Wisconsin (UW) solution and fixed by immersion. Ultrastructural differences in the swelling of capillary endothelial cells and myocytes were quantitatively evaluated using stereological methods. Endothelial cells were somewhat more swollen after St. Thomas perfusion than those in beating and fibrillating hearts. HTK-arrested hearts showed significantly lower values for cellular edema than beating hearts. UW perfusion resulted in the (significantly) lowest degree of endothelial cell edema. Edematous changes in myocytes were significantly greater in St. Thomas-arrested hearts than in UW- or HTK-arrested hearts. Cardiomyocyte edema in beating and fibrillating hearts was comparable to that in St. Thomas-perfused hearts. Thus, the stereol-ogical analysis revealed significant differences between cardioplegic solutions in structural preservation of myocardial ultrastructure.
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  • 12
    ISSN: 1432-2307
    Keywords: Key words Inflammation of the lung ; Biopsy ; Ultrastructure ; Laser therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Examination of 127 biopsy specimens from 45 patients with inflammatory lung diseases showed changes consistent with increased permeability of the capillary endothelial cells as an initial stage in the development of the inflammatory reaction. Associated interstitial oedema, deformation of the interalveolar septa, and structural disorganization of alveolar epithelium cells occur, and local microcirculatory problems result in tissue hypoxia and fibrosis. The ultimate morphological picture is determined largely by the intensity of repair. Laser biostimulation minimizes the inflammation and stabilizes fibroplastic process.
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  • 13
    ISSN: 1432-2307
    Keywords: Key words Capillary basement membrane ; Inflammatory myopathy ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The capillary basement membranes from 16 skeletal muscle biopsies from patients with a clinical and histological diagnosis of inflammatory myopathy and from six controls were analysed ultrastructurally and morphometrically. Resin sections from 244 endomysial capillaries were examined by light microscope, and the results were correlated with findings seen in electron micrographs of these capillaries. The ultrastructural morphometric measurements and the statistical analysis showed that the capillary basement membrane was thick and multilaminated in 87% specimens affected by inflammatory myopathy. No thick or multilaminated basement membrane was observed in controls. In inflammatory myopathy the endomysial space next to the capillaries contained an increased amount of collagen fibrils and showed signs of a chronic reparative process. It is suggested that the thick multilaminated basement membrane in inflammatory myopathy represents an advanced stage of vascular regeneration.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Urological research 27 (1999), S. 454-461 
    ISSN: 1434-0879
    Keywords: Key words Cold-restraint stress ; Urinary bladder ; Interstitial cystitis ; Mast cell ; Urothelium ; Ultrastructure ; Ruthenium red ; Flow cytometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Stress is associated with many diseases of unknown aetiology. This study demonstrates the effects of cold-restraint stress on the morphology of the urinary bladder. Additionally, it compares the results obtained with the morphology of the interstitial cystitis. The animals were subjected to three hours of cold-restraint stress and then starved for 48 h. The morphology and histochemistry of the urinary bladder was investigated with light and electron microscopy. The proliferative activity was analysed via flow cytometry. Increased and degranulated mast cells in the mucosa, leucocyte infiltration in the lamina propria, vacuole formation in the urothelial cells, loose tight junction, dilated intercellular spaces and altered proliferative activity were observed in the stress group when compared with the control. The increase in the number of mast cells and especially degranulated mast cells and vacuole formation and the loose tight junction of the urothelium correlated with the histopathological findings of interstitial cystitis.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 12 (1999), S. 99-109 
    ISSN: 1432-2145
    Keywords: Key words Arabidopsis thaliana ; Megasporogenesis ; Meiosis ; Ultrastructure ; Cellular polarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In this study, megasporogenesis of the plant model Arabidopsis thaliana was investigated by electron microscopy for the first time. The data described here could constitute a reference for future investigations of Arabidopsis mutants. During the beginning of meiosis the megaspore mother cell shows a polarity created by unequal distribution of organelles in the cytoplasm. Plastids accumulate in the chalazal region and long parallel saccules of endoplasmic reticulum, small vacuoles and some dictyosomes are found in the micropylar region. Plasmodesmata are abundant in the chalazal cell wall. The nucleus is almost centrally localized and contains a prominent excentric nucleolus and numerous typical synaptonemal complexes. After the second division of meiosis the four megaspores are separated by thin cell walls crossed by numerous plasmodesmata and do not show significant cellular organization. The young functional megaspore is characterized by a large nucleus and a large granular nucleolus. The cytoplasm is very electron dense due to the abundance of free ribosomes and contains the following randomly distributed organelles: mitochondria, a few short saccules of endoplasmic reticulum, dictyosomes and undifferentiated plastids. However, there is no apparent polarity, except for the distribution of some small vacuoles which are more abundant in the micropylar region of the cell. The degenerating megaspores are extremely electron dense and do not show any substructure.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 97 (1999), S. 509-514 
    ISSN: 1432-0533
    Keywords: Key words Hereditary inclusion body myopathy ; Desmin storage myopathy ; Ultrastructure ; Immmunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report two adult familial cases of inclusion body myopathy (IBM) with desmin storage in skeletal muscle. Clinically, both patients presented late-onset, progressive, symmetrical, both proximal and distal muscle weakness. Muscle biopsy findings were identical in both cases and consisted of marked variability in fiber size, increased number of central nuclei and vacuolation involving 10% of fibers. Single or multiple vacuoles were located subsarcolemmally or in the center, and were rimmed by basophilic material. At the ultrastructural level, tubulofilamentous nuclear and cytoplasmic inclusions of 16–21 nm in diameter were frequently observed. In addition, large subsarcolemmal and central deposits composed of electron-dense granular material were present in many fibers. Immunocytochemistry revealed staining for desmin, vimentin and ubiquitin within both inclusions and vacuolated fibers. Possible structural and functional associations between these two types of muscle changes remain unclear. They may either represent two coexistent disease processes or merely reflect an abnormal form of muscle fiber degradation, with unidentifiable specificity.
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  • 17
    ISSN: 1432-0533
    Keywords: Key words Amyotrophic lateral sclerosis ; Bunina body ; Guam ; Immunohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An investigation of Bunina bodies is important when studying the pathoetiology and pathomechanisms involved in amyotrophic lateral sclerosis (ALS). It may serve as a clue essential for the study of the pathogenesis of Guamanian amyotrophic lateral sclerosis (ALS-G), and it may provide a means of answering the question of whether ALS-G is the same disease as classical ALS or a different entity. In ALS-G, however, no precise histochemical, immunohistochemical, or detailed ultrastructural examination has been published to date. To elucidate the pathological differences/similarities of Bunina bodies between classical ALS and ALS-G, we performed histochemical, immunohistochemical, topographic and ultrastructural examinations. Histochemically, hematoxylin and eosin, Masson’s trichrome, methylgreen-pyronin, phosphotungstic acid-hematoxylin, Klüver-Barrera, Bodian and periodic acid-Schiff staining were utilized. Immunohistochemical examination was performed using antibodies for cystatin C, ubiquitin, Tau-2, Cu/Zn superoxide dismutase, phosphorylated neurofilament and glial fibrillary acidic protein. Histochemical findings were consistent with those previously described for classical ALS. The immunohistochemical study showed that in ALS-G Bunina bodies were intensely labeled by an anti-cystatin C antibody. Topographic examination demonstrated that Bunina bodies were distributed in the spinal anterior horns and Clarke’s column in the spinal cord. Ultrastructurally, Bunina bodies were composed of electron-dense amorphous/ granular material accompanied by vesicular structures and neurofilaments. The results of the present study have revealed that the pathological features of Bunina bodies in ALS-G are identical to those seen in classical ALS. These findings strongly suggest that a similar degenerative process occurs in the spinal anterior horn cells in both ALS-G and classical ALS.
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  • 18
    ISSN: 1432-0533
    Keywords: Key words Polyglucosan body ; Periodic ; acid-Schiff-positive granules ; Mouse brain ; Immunohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Periodic acid-Schiff-positive granules (PGs) appear in the mouse brains in relation to advancing age. The exact location and pathophysiological significance of PGs, however, are not fully understood. The incidence, staining properties, and topographical distributions of PGs in the brains of 17 AKR mice ranging in age from 7 to 18 months were examined histochemically and immunohistochemically using antibody KM279 raised against a polyglucosan. In addition, to define the precise site of PG formation, we investigated the brains of 4 AKR mice of 24 months of age using conventional and immunoelectron microscopy. PGs were seen in all mice examined and the levels were increased with age. The PGs were located predominantly in the hippocampus and, to a lesser extent, in the cerebellum and olfactory bulb. Immunohistochemically, PGs in the hippocampus and cerebellum were labeled uniformly with KM279. On immunoelectron microscopy with this monoclonal antibody, the fibrillar or membranous structures corresponding to PGs seen using light microscopy were labeled specifically with gold particles. With conventional electron microscopy, fibrillar or membranous structures were seen along with synaptic vesicles and dense-core granules. Moreover, around the cells containing PGs, a few synaptic junctions with neighboring cells were observed, indicating that the cells contributing to formation of PGs were neuronal cells. The positive immunoreactivity of AKR mouse PGs for the antibody KM279 suggests that the PGs and similar structures in other species may share a common antigenicity. Thus, it is assumed that PGs in AKR mice might result from some abnormalities in glucose metabolism.
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  • 19
    ISSN: 1432-0533
    Keywords: Key words Ischemia ; Protein synthesis ; Translation ; Ultrastructure ; Hippocampus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract During post-ischemic brain reperfusion there is a substantial reduction of protein synthesis in selectively vulnerable neurons. Normal protein synthesis requires a functional translation initiation complex, a key element of which is eukaryotic initiation factor 2 (eIF2), which in a complex with GTP introduces the met-tRNAi. Phosphorylation of Ser51 on the α subunit of eIF2 [eIF2α(P)] generates a competitive inhibitor of eIF2B, thereby preventing the replenishment of GTP onto eIF2, thus blocking translation initiation. It has been shown that the conditional expression of an eIF2α mutant (Asp substituted for Ser51) imitating the negative charge of Ser51 (P) induces apoptosis. During the first 10 min of post-ischemic reperfusion, there is an approximately 20-fold increase in eIF2α(P) seen in the cytoplasm of CA1 hippocampal neurons, and, by 1 h, there is also accumulation of eIF2α(P) in the nucleus. We utilized post-embedding electron microscopical immunogold methods to examine the localization of eIF2α(P) during reperfusion. Immunogold particles (10 nm) were concentrated chiefly along the rough endoplasmic reticulum and in association with the membranes of the nuclear envelope in CA1 neurons. Aggregations of gold particles in the nucleus were concentrated: (1) within and around the nucleolus, (2) associated to strands of heterochromatin, and (3) along putative nuclear filaments. The presence of eIF2α(P) in the nucleolus probably reflects its association with nascent ribosomal subunits. The β-subunit of eIF2 has a zinc finger and polylysine blocks analogous to those on other proteins that affect transcription. The association of eIF2α(P) with chromatin may have important implications for transcription.
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  • 20
    ISSN: 1432-0533
    Keywords: Key words Amyloid precursor protein ; immunoreactivity ; Axonal injury ; Microwave antigen retrieval ; Traumatic brain injury ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Antibodies to the amyloid precursor proteins (APP) have become routine markers for detecting traumatically induced axonal injury (AI) in animals and man. Unfortunately, the techniques used to visualize these proteins are not compatible with routine electron microscopic (EM) analysis. In the current communication, we describe a method for the ultrastructural visualization of antibodies to APP and, using this method, we identify a previously unrecognized population of traumatically injured axons. Rats were subjected to an impact acceleration traumatic brain injury and allowed to survive 30 min to 3 h postinjury. The animals were then perfused, their brains sectioned on a vibratome and the sections prepared for immunocytochemistry using a computer-controlled microwave capable of temperature regulation. The use of temperature-controlled microwave energy unmasked APP antigenic epitopes without sacrificing ultrastructural detail. The APP antibody was found in two distinct populations of reactive axons that differed in size, morphology, location, and temporal progression. Comparable to previous descriptions, one population showed traumatically related reactive changes that led to swelling and disconnection. The other population, however, revealed unanticipated changes reflected in nodal and paranodal swelling of small continuous fibers that showed no evidence of disconnection during the time periods assessed. These studies provide new insight into the complexity of the pathobiology of AI, while describing a novel approach for enhancing APP immunoreactivity at the EM level.
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  • 21
    ISSN: 1432-069X
    Keywords: Key words p75 nerve growth factor receptor ; (p75 NGFr) ; Immunoreactivity ; Ultrastructure ; Prurigo nodularis ; Nerve fiber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Prurigo nodularis is an inflammatory skin disease characterized by neurohyperplasia. Neurotrophins and their receptors play a critical role in nerve growth, differentiation, maturation and maintenance, including cutaneous nerve fiber growth and innervation. They may also be responsible for events related to the growth and differentiation control of keratinocytes. To explore the exact distribution of the p75 low-affinity nerve growth factor receptor (p75 NGFr) in the cutaneous nerve components, p75 NGFr immunofluorescence as well as ultrastructural immunohistochemical studies were performed on prurigo nodularis lesional skin and normal human skin samples. The immunofluorescence results revealed that nerve fibers and bundles were increased in number and size in lesional upper dermis with stronger p75 NGFr immunoreactivity than in the corresponding normal tissue. At the ultrastructural level, a lot of nerve fibers clustered together in the prurigo nodularis dermal tissue. The axons were enlarged and branched, but the axons themselves seldom showed any NGFr immunoreactivity. The Schwann cell bodies were extended and irregularly shaped, and tended to separate into many branches enveloping the axons. The Schwann cell membrane showed strong p75 NGFr immunoreactivity. The perineurium cells also revealed strong p75 NGFr immunoreactivity. The Schwann cells inside the perineurium were less p75 NGFr-immunoreactive than those outside the perineurium. The membrane of certain basal keratinocytes showed NGFr immunoreactivity as well. The present results indicate that overexpression of p75 NGFr in Schwann cells and perineurium cells could contribute to the neurohyperplasia in prurigo nodularis.
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  • 22
    ISSN: 1432-0878
    Keywords: Key words ECL cells ; Gastrin ; Reserpine ; Organelles ; Ultrastructure ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The histamine-storing ECL cells in the stomach play a key role in the control of acid secretion. They contain granules, secretory vesicles and microvesicles, and sustained gastrin stimulation results in the additional formation of vacuoles and lipofuscin bodies. The cells are rich in the vesicle monoamine transporter type-2 (VMAT-2), which can be inhibited by reserpine. The present study examines the effect of reserpine on ECL-cell ultrastructure and histamine compartmentalization. Rats received reserpine and/or gastrin. Reserpine was given twice by the intraperitoneal route (25 mg/kg once daily). Gastrin-17 was given by subcutaneous infusion (5 nmol/kg/h), starting at the time of the first reserpine injection and continuing for 4 days when the rats were killed. At this stage, histamine in the oxyntic mucosa was unaffected by reserpine but elevated by gastrin. Immunocytochemical analysis (confocal microscopy) showed ECL-cell histamine in control and gastrin-treated rats to be localized in cytoplasmic organelles (e.g., secretory vesicles). After treatment with reserpine alone or reserpine+gastrin, ECL-cell histamine occurred mainly in the cytosol. Planimetric analysis (electron microscopy) of ECL cells showed reserpine to increase the number, size and volume density of the granules and to reduce the size and volume density of the secretory vesicles. Gastrin reduced the number and volume density of granules and secretory vesicles, increased the number and volume density of microvesicles and caused vacuoles and lipofuscin bodies to appear. Reserpine+gastrin increased the number, volume density and size of the granules. Reserpine prevented the effects of gastrin on secretory vesicles, vacuoles and microvesicles, but did not prevent the development of lipofuscin. Our findings are in line with the views: (1) that preformed cytosolic histamine is taken up by granules/secretory vesicles via VMAT-2, that histamine is instrumental in the transformation of granules into secretory vesicles and in their consequent enlargement and (2) that vacuoles are formed by the fusion of large secretory vesicles.
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  • 23
    ISSN: 1432-0878
    Keywords: Key words Mechanoreceptors ; Synaptic proteins ; Histochemistry ; Ultrastructure ; Slit sensilla ; Hair sensilla ; Cupiennius salei (Chelicerata)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Indirect immunocytochemical tests were used at the light- and electron-microscopic levels to investigate peripheral chemical synapses in identified sensory neurons of two types of cuticular mechanosensors in the spider Cupiennius salei Keys.: (1) in the lyriform slit-sense organ VS-3 (comprising 7–8 cuticular slits, each innervated by 2 bipolar sensory neurons) and (2) in tactile hair sensilla (each supplied with 3 bipolar sensory cells). All these neurons are mechanosensitive. Application of a monoclonal antibody against Drosophila synapsin revealed clear punctate immunofluorescence in whole-mount preparations of both mechanoreceptor types. The size and overall distribution of immunoreactive puncta suggested that these were labeled presynaptic sites. Immunofluorescent puncta were 0.5–6.8 μm long and located 0.5–6.6 μm apart from each other. They were concentrated at the initial axon segments of the sensory neurons, while the somata and the dendritic regions showed fewer puncta. Western blot analysis with the same synapsin antibody against samples of spider sensory hypodermis and against samples from the central nervous system revealed a characteristic doublet band at 72 kDa and 75 kDa, corresponding to the apparent molecular mass of synapsin in Drosophila and in mammals. Conventional transmissionelectron-microscopic staining demonstrated that numerous chemical synapses (with at least 2 vesicle types) were present at these mechanosensory neurons and their surrounding glial sheath. The distribution of these synapses corresponded to our immunofluorescence results.Ultrastructural examination of anti-synapsin-stained neurons confirmed that reaction product was associated with synaptic vesicles. We assume that the peripheral synaptic contacts originate from efferents that could exert a complex modulatory influence on mechanosensory activity.
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  • 24
    ISSN: 1432-0878
    Keywords: Key words Melanin-concentrating hormone neurons ; Lateral hypothalamic slice culture ; Immunocytochemistry ; Ultrastructure ; In situ hybridization ; Competitive RT-PCR ; Leptin assay ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Hypothalamic slices containing the lateral hypothalamic area (LHA) were prepared from 6- to 8-day-old rats and maintained in stationary culture for up to 35 days in order to analyse how well the melanin-concentrating hormone (MCH) neurons survived. As previously reported for other brain areas, this method yielded a long-term well-preserved organotypic organization. Light- and electron-microscopic investigations showed that differentiation continued and that synaptic contacts developed in vitro. After a period of elimination of damaged cells and fibres, most of the remaining neurons and glial cells retained a normal morphology throughout the culture period. MCH neurons, in particular, survived well as attested by the strong immunocytochemical and in situ hybridization signals still observed after several weeks. In a comparison with the day of explantation, competitive reverse transcription/polymerase chain reaction demonstrated the remarkable stability of the level of MCH mRNA at least until the 20th day in culture; after 30 days, the clear decrease in this level seemed to be correlated with a loss of MCH neurons, rather than with a decrease in MCH expression. After 10 days of culture, the incubation of slices in the presence of the hormone leptin (50 ng/ml) resulted in a strong decrease of MCH gene expression, suggesting that MCH neurons retained their physiological properties. Thus, the LHA slice stationary culture, especially between one and three weeks (i.e. after tissue stabilization and before extensive cell loss), appears to be a suitable method for physiological and pharmacological studies of these neurons.
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  • 25
    ISSN: 1432-0878
    Keywords: Key words Chloride cells (mitochondria-rich cells) ; Teleost larvae ; Osmoregulation ; Immunohistochemistry ; Quantification ; Ultrastructure ; Oreochromis mossambicus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Integumental and branchial chloride cells of tilapia larvae (Oreochromis mossambicus) were studied at the light-microscopical and ultrastructural level. Total numbers and distribution of chloride cells were quantified after immunostaining of cross sections of the entire larvae with an antibody against the α-subunit of Na+/K+-ATPase. The majority (66%) of Na+/K+-ATPase-immunoreactive (ir) cells, i.e. chloride cells, of freshwater tilapia larvae were located extrabranchially up to 48 h after hatching. Five days after hatching, the majority (80%) of chloride cells were found in the buccal cavity. Transfer of 24-h-old larvae to 20% sea water speeded up this process; 24 h after transfer (i.e. 48 h after hatching), the majority (59%) of chloride cells were located in the buccal cavity. The branchial chloride cell population of 24-h- and 120-h-old larvae consisted of immature, mature, apoptotic and necrotic chloride cells. However, relatively more immature chloride cells were observed in freshwater larvae (42–63%) than in (previously studied) freshwater adults (21%), illustrating the developmental state of the gills. After transfer to sea water, the incidence of degenerative chloride cells did not change. Furthermore, the incidence of immature cells had decreased and a new subtype of chloride cells, the ”mitochondria-poor” cells, appeared more frequently. These mitochondria-poor chloride cells were characterised by an abundant tubular system and relatively few mitochondria, which were aligned at the border or concentrated in one part of the cytoplasm. Most of these cells did not contact the water. The function of their enhanced appearance after seawater transfer is unknown.
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  • 26
    ISSN: 1615-2573
    Keywords: Endomyocardial biopsy ; Dilated cardiomyopathy ; Children ; Ultrastructure ; Basal lamina layering of capillary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We analyzed the electron-microscopic features of endomyocardial biopsy from pediatric patients with dilated cardiomyopathy (DCM). The specimens examined were taken from the right ventricle of ten patients aged from 2 to 15 years (mean 9.7 years). Biopsy specimens from eight patients with congenital heart disease (tetralogy of Fallot), aged from 3 to 12 (mean 7.3 years), and ten adult patients with DCM, aged from 32 to 60 (mean 45 years), were also examined. Patients considered to have endocardial fibroelastosis, arrhythmogenic right ventricular cardiomyopathy, specific cardiomyopathy, or coronary heart disease were excluded from this study. Specimens from pediatric patients with DCM showed various degrees of ultrastructural abnormalities of myocytes, including myofibrillar fragmentation, mitochondrial abnormalities, and intracellular edema. The ultrastructurally determined contractility failure index based on the severity of myocardial degeneration at the electronmicroscopic level was 4.9 ± 1.1. This value was significantly higher than that in patients with tetralogy of Fallot (0.9 ± 0.6,P 〈 0.001) but was not significantly different from that in adult patients with DCM (6.1 ± 2.6). The index of pediatric patients with DCM who died within 3 years was high (6.0 ± 0.8). Basal lamina layering of a capillary (BLL) in the myocardium was revealed in 1 of the 10 (10%) pediatric patients with DCM and in 6 of the 10 (60%) adult patients with DCM (P 〈 0.05). No BLL was noted in the patients with tetralogy of Fallot. These findings may be related to the pathogenesis of DCM in children and adults.
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  • 27
    ISSN: 1615-6102
    Keywords: Cumulus oophorus ; Ovarian follicle ; Fertilization ; Ultrastructure ; Immunocytochemistry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The fine structure of the human cumulus oophorus has been reviewed on the basis of scanning and transmission electron microscopic observations as well as of immunofluorescence data. Tissues sampled from preovulatory ovarian follicles and cumulus-enclosed oocytes and fertilized eggs (collected from the oviduct or obtained during in vitro fertilization procedures) have been evaluated from a microtopographic and morphodynamic point of view in order to better clarify the possible role of this population of cells. In particular, the following aspects have been studied and discussed: the presence of multiple close contacts (modulated by the interposition of the zona pellucida) between the oocyte surface and the long microvillous evaginations projecting from the inner aspect of corona cells surface (through these structures the intraovarian cumulus oophorus may control oocyte growth and metabolism up until the time of ovulation); the occurrence of different subpopulations of cells (steroid-synthetic cells, cells producing adhesive proteins, leukocytes, macrophages) in the postovulatory, extraovarian cumulus oophorus surrounding oocytes, zygotes and early developing embryos. All these elements found in the cumulus mass may positively act, through their paracrine activities, on the chemical composition of the microenvironment in which fertilization occurs.
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  • 28
    ISSN: 1615-6102
    Keywords: Anatomy ; Floral nectary ; Modified stomata ; Phloem ; Pisum sativum ; Stereology ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The floral nectary ofPisum sativum L. is situated on the receptacle at the base of the gynoecium. The gland receives phloem alone which departed the vascular bundles supplying the staminal column. Throughout the nectary, only the companion cells of the phloem exhibited wall ingrowths typical of transfer cells. Modified stomata on the nectary surface served as exits for nectar, but stomatal pores developed well before the commencement of secretion. Furthermore, stomatal pores on the nectary usually closed by occlusion, not by guard-cell movements. Pore occlusion was detected most frequently in post-secretory and secretory glands, and less commonly in pre-secretory nectaries. A quantitative stereological study revealed few changes in nectary fine structure between buds, flowers secreting nectar, and post-secretory flowers. Dissolution of abundant starch grains in plastids of subepidermal secretory cells when secretion commenced suggests that starch is a precursor of nectar carbohydrate production. Throughout nectary development, mitochondria were consistently the most plentiful organelle in both epidermal and subepidermal cells, and in addition to the relative paucity of dictyosomes, endoplasmic reticulum, and their associated vesicles, the evidence suggests that floral nectar secretion inP. sativum is an energy-requiring (eccrine) process, rather that granulocrine.
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  • 29
    ISSN: 1615-6102
    Keywords: Plasmalemmic cord ; Pollen grain ; Ultrastructure ; Magnolia ×soulangeana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary InMagnolia ×soulangeana pollen grains the generative cell (GC) does not become totally free within the vegetative cell (VC), at least until the pollen tube emergence. Due to a deviation in its detachment process from the sporoderm, the opposing ends of the VC plasmalemma do not fuse themselves when the GC moves away from the intine. Consequently, the interplasmalemmic space surrounding the GC does not become isolated but rather maintains continuity with the sporoderm through a complex formation that we have called plasmalemmic cord. The real existence of this formation was confirmed through serial sectioning showing the plasmalemmic cord to consist of the VC plasmalemma. In its initial portion it is occupied by a reasonably accentuated wall ingrowth of the inner layer of the intine (intine 3). In the remainder portion, neither of the cytochemical tests used in this work have revealed the presence of a significant amount of wall material. However, ultrathin sections of samples processed either chemically or by cryofixation showed the existence of an intricate system of tubules and vesicles, some of which are evaginations of the VC plasmalemma. The hypothesis that the plasmalemmic cord may have a role in the complex interactions between the two pollen cells is discussed.
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  • 30
    ISSN: 1615-6102
    Keywords: Endosymbiont ; Mycetocyte ; Mycetome ; Oocyte ; Transovarial transmission ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary All anoplurans live symbiotically with prokaryotic microorganisms hosted in specialized cells, termed mycetocytes. In nymphs and males mycetocytes are distributed between midgut epithelial cells. In females, besides the midgut, mycetocytes are found in the reproductive organs where they are located at the base of ovarioles in contact with lateral oviducts. The mycetocyte-associated symbionts are transmitted from one generation to the next transovarially. Here, the results of histological and ultrastructural studies on the distribution and transmission of symbiotic microorganisms within the ovaries of the anopluranHaematopinus suis are presented. Interestingly, during advanced oogenesis (i.e., choriogenesis) of this species all symbionts are localized extracellularly and form a tight mass located at the posterior pole of the oocyte just below the hydropyle. In insects studied so far, such localization of transovarially transmitted microorganisms has been reported only in the closely related speciesHaematopinus eurysternus.
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  • 31
    ISSN: 1432-0878
    Keywords: Key words Neuromelanin ; Neuron ; Peroxidase ; Oxygen metabolism ; High-definition light microscopy ; Electron microscopy ; Ultrastructure ; Cytochemistry ; Substantia nigra ; Lumbricusterrestris (Annelida)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Histochemical examination of 1-μm tissue sections from the dorsal nerve plexus of the earthworm, Lumbricus terrestris, reveals multiple brown intraneuronal granules. These granules contain material morphologically and histochemically consistent with neuromelanin. When viewed with transmission electron microscopy, these were seen as single membrane-enclosed biphasic granules with diameters of 370–730 nm. Exposure of L. terrestris to high-level environmental oxygen resulted in an increase in the number of neuromelanin-like pigment granules within the neurons of the circular muscle layer. As measured by ortho-phenylenediamine hydrochloride, the endogenous peroxidase activity of extracts from worms incubated in high-level environmental oxygen was 51% more than controls. The endogenous peroxidase activity was localized in situ with 3,3-diaminobenzidine (DAB) and was found to increase in and around the neuromelanin-like pigment-containing neurons within the circular muscle layer. These studies suggest that the nerve net of L. terrestris may serve as a model to study the role of neuromelanin production in oxidative stress and its relationship to endogenous peroxidases.
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  • 32
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 295 (1999), S. 151-158 
    ISSN: 1432-0878
    Keywords: Key words Class II MHC-positive cells ; Human leukocyte antigen-DR ; Dental pulp ; Dendritic cells ; Macrophages ; Ultrastructure ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The distribution and ultrastructure of class II major histocompatibility complex (MHC)-positive cells were investigated in human dental pulp, employing immunohistochemistry using an anti-human leukocyte antigen (HLA)-DR-monoclonal antibody. HLA-DR-immunopositive cells, appearing spindle-like or dendritic in profile, were densely distributed throughout the dental pulp. Under the electron microscope, these cells exhibited various sizes of vesicles containing clear or opaque contents, multivesicular bodies and characteristic fine tubulovesicular structures in their cytoplasm. Some reactive cells possessed coated pits and vesicles including electron-dense materials, indicating an active endocytosis. At the periphery of the pulp tissue, the HLA-DR-immunopositive cells were predominantly situated in the subodontoblastic layer, with some located in the odontoblast layer and/or predentin and extending their cytoplasmic processes into the dentinal tubules. Cell processes of these cells occasionally made contact with several odontoblast processes in the same way as the nerve fibers in the predentin. These cells never contained the typical phagosomes frequently observed in the HLA-DR-immunoreactive macrophages in the subodontoblastic layer and the pulp core. The results suggest that the HLA-DR-immunopositive cells in the odontoblast layer and/or predentin have some regulatory function on the odontoblasts under physiological conditions, in addition to their involvement in the initial defense reaction after tooth injury.
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  • 33
    ISSN: 1432-0878
    Keywords: Key words Teleost fish ; Puberty ; Testes ; Sex steroids ; Ultrastructure ; Steroidogenesis ; Clarias gariepinus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The present report focuses on the mechanism(s) involved in the steroid-induced decrease of androgen production in immature African catfish testes that was observed in previous studies. Juvenile animals were implanted with Silastic pellets containing different 11-oxygenated androgens (11-ketotestosterone, KT; 11β- hydroxyandrostenedione, OHA; 11-ketoandrostenedione, KA), testosterone (T) or estradiol-17β (E2). Control groups received steroid-free pellets. Two weeks later, testis tissue fragments were either incubated with increasing concentrations of catfish luteinizing hormone (LH), or incubated with [3H]-pregnenolone ([3H]-P5) or [3H]-androstenedione ([3H]-A). Tissue fragments were also prepared for the quantitative assessment of Leydig cell morphology. Most of the parameters studied were not affected significantly by implantation of E2. Implantation of all androgens inhibited both the basal and the LH-stimulated androgen secretory capacity in vitro. This was associated with a reduced size of the Leydig cells and loss of half of their mitochondria. The studies on the metabolism of tritiated steroid hormones indicated that steroidogenic steps prior to 11β-hydroxylation, probably C17–20 lyase activity, were affected by all androgens. Although the effects of 11-oxygenated androgens and T on Leydig cells were mostly similar, previous work showed that only the 11-oxygenated androgens stimulated spermatogenesis, suggesting that distinct mechanisms of action are used by 11-oxygenated androgens and T. These mechanisms, however, seem to merge on the same target(s) to impair Leydig cell androgen production. Such a negative feedback mechanism may be of relevance in the context of the decline in androgen secretion per milligram testis tissue that accompanies the first wave of spermatogenesis in pubertal African catfish.
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  • 34
    Electronic Resource
    Electronic Resource
    Springer
    Parasitology research 85 (1999), S. 999-1006 
    ISSN: 1432-1955
    Keywords: Key wordsEchinococcus granulosus ; Praziquantel ; Metacestode ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The efficacy of praziquantel against the metacestode of Echinococcus granulosus was studied by means of in vitro incubations or in vivo experiments. The results of in vitro incubations indicated that the effectiveness of praziquantel was higher when the parasite material comprised cysts from cyst masses than in the case of intact cysts that retained their adventitial layer. Ultrastructural alterations in the germinal layer of collapsed cysts incubated in vitro were detected. The results obtained in mice after 4 months of treatment demonstrated no significant difference between the control and treated groups with regard to the number and wet weight of developed cysts. However, ultrastructural alterations were detected in the cyst tissue that were similar to those described in the in vitro experiment. In contrast, the effect of chemoprophylaxis on the number and the wet weight of developed cysts was extremely significant as compared with the control value, the efficacy being 99.41% and 98.32%, respectively. Moreover, ultrastructural observations of the cyst tissue revealed loss of its integrity, and no intact cyton was observed in the germinal layer of the developed cyst.
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  • 35
    ISSN: 1432-1955
    Keywords: Key words Monogenea ; Capsalidae ; Benedenia rohdei ; B. lutjani ; Ectoparasites ; Lutjanus carponotatus ; Glands ; Ultrastructure ; Adhesion ; Attachment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The anterior adhesive areas of Benedenia rohdei from the gills and B. lutjani from the pelvic fins of Lutjanuscarponotatus at Heron Island, Australia, were studied using scanning and transmission electron microscopy. All specimens were fixed when detached from host tissue. Both monogenean species have two disc-like anteroventral attachment organs, each of which has an anterolateral adhesive area divided into three adjacent zones by tegument from the ventral surface of the attachment organ. A rod-shaped secretion and a smaller, roughly spherical secretion are associated with the anterior adhesive areas in both species; a third type of secretion occurs anteriorly but outside these adhesive areas. The electron-dense spherical secretory bodies released onto the anterior adhesive zones in these Benedenia spp. are of a single type and differ ultrastructurally from those previously reported in monogeneans living on teleost hosts. A correlation, therefore, between secretion morphology and host type is not supported. No relationship was found between parasite microhabitat and secretion morphology.
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  • 36
    ISSN: 1432-136X
    Keywords: Key words Freeze tolerance ; Sciatic nerve ; Cryoinjury ; Dehydration ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We investigated function and ultrastructure of sciatic nerves isolated from wood frogs (Rana sylvatica) endemic to the Northwest Territories, Canada, following freezing at −2.5 °C, −5.0 °C, or −7.5 °C. All frogs frozen at −2.5 °C, and most frogs (71%) frozen at −5.0 °C, recovered within 14 h after thawing began; however, frogs did not survive exposure to −7.5 °C. Sciatic nerves isolated from frogs frozen at −7.5 °C were refractory to electrical stimulation, whereas those obtained from frogs surviving exposure to −2.5 °C or −5.0 °C generally exhibited normal characteristics of compound action potentials. Frogs responded to freezing by mobilizing hepatic glycogen reserves to synthesize the cryoprotectant glucose, which increased 20-fold in the liver and 40-fold in the blood. Ultrastructural analyses of nerves harvested from frogs in each treatment group revealed that freezing at −2.5 °C or −5.0 °C had little or no effect on tissue and cellular organization, but that (lethal) exposure to −7.5 °C resulted in marked shrinkage of the axon, degeneration of mitochondria within the axoplasm, and extensive delamination of myelin sheaths of the surrounding Schwann cells.
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  • 37
    ISSN: 1861-387X
    Keywords: Meningioma ; Intranuclear inclusion ; Immunohistochemistry ; Ultrastructure ; Intermediate filament
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe a case of meningothelial meningioma with a large number of intranuclear inclusions. Morphologically, these are divided into cytoplasmic inclusions and nuclear vacuoles. The cytoplasmic inclusion has a limiting membrane with cell organelles and filaments. Inclusions of this type are generally eosinophilic, like the cytoplasm. However, there are many inclusions that are more eosinophilic than the cytoplasm or that have a ground-glass appearance. Some of them may contain fine or coarse granules. On the other hand, the nuclear vacuole lacks a limiting membrane and appears empty. In most of the inclusions of this type, there is a faintly basophilic substance in the margin. Generally, the cytoplasmic inclusions are as immunopositive as cytoplasm with vimentin, but some of these cytoplasmic inclusions are more reactive. Under the electron microscope, abnormal aggregation of intermediate filaments is recognized in the cytoplasmic inclusions. It is considered that a strong reaction of cytoplasmic inclusions with vimentin immunostaining is due to abnormal aggregation of intermediate filaments. The present study distinctly demonstrates abnormal localization of intermediate filaments in the cytoplasmic inclusions, and it is suggested that the cytoskeleton participates in the evolution of the cytoplasmic inclusions.
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  • 38
    ISSN: 1432-0878
    Keywords: Key words Chondrocyte ; Synoviocyte ; Co-culture ; Proliferation ; Lipid peroxidation ; Cytotoxicity ; Ultrastructure ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Objective: A new co-culture system of rat articular chondrocytes and synoviocytes (HIG-82; cell line) was incubated with phorbol myristate acetate (PMA), H2O2 or a combination of Fe2+ and ascorbic acid to simulate inflammation-like radical attacks in articular joints. Methods: Chondrocytes were characterized by immunocytochemistry against collagen type II, transmission electron (TEM) and light microscopy. Lipid peroxidation was investigated by measuring thiobarbituric-acid-reactive material in the supernatants, cytotoxicity by determining release of lactate dehydrogenase and proliferation by measuring [3H]thymidine incorporation, culture protein and DNA. Results: PMA or Fe2+ and ascorbic acid induced lipid peroxidation in chondrocytes and synoviocytes that was decreased significantly in co-cultures. PMA and H2O2 dose dependently induced release of lactate dehydrogenase in chondrocytes, which was lowered in co-cultures or in previously co-cultured chondrocytes to a nearly basal level. In contrast, conditioned media of synoviocyte cultures showed no lowering effect on the radical-induced toxicity. Protection against H2O2-induced damage of cellular membranes by co-culturing was also shown by TEM. Synoviocytes released chondrocyte-stimulating growth factors spontaneously without previous interaction. Conclusion: Chondrocytes establish protective mechanisms against reactive oxygen species via an interaction with synoviocytes. Our co-culture model presents a possible way to study mechanisms of inflammation in articular joints under defined conditions.
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