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  • 1
    Electronic Resource
    Electronic Resource
    Organization of identified fiber tracts in the rat fimbria-fornix: an anterograde tracing and electron microscopic study (1996)
    Springer
    Anatomy and embryology 193 (1996), S. 481-493 
    Details
    ISSN: 1432-0568
    Keywords: Phaseolus vulgaris-leucoagglutinin ; Hippocampus ; Septum ; Entorhinal cortex ; Limbic system ; Fimbria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The fimbria is a major route for afferent and efferent fibers of the hippocampal formation. However, little is known about the intrinsic organization of the fimbria-fornix complex. In this study, the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHAL) was used to analyze the ultrastructure and topography of identified fiber tracts within the fimbria-fornix. Septo-hippocampal fibers are loosely distributed throughout the fimbria-fornix. Commissural fibers cross the midline in the ventral hippocampal commissure and form a tight fiber bundle in the fimbria. Crossed entorhino-hippocampal fibers cross the midline in the ventral hippocampal commissure rostral to the commissural fiber bundle, and crossed entorhino-entorhinal fibers pass through the dorsal hippocampal commissure. This suggests a topographical organization of fiber tracts within the fimbria-fornix that reflects the laminar organization of the hippocampal target structure: fibers of the diffusely terminating septohippocampal projection are loosely distributed throughout the fimbria-fornix, while those projections that are known to terminate in specific laminae of the hippocampal formation (commissural projection, crossed entorhino-hippocampal projection) form fiber bundles within the fimbria and the ventral hippocampal commissure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185879
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  • 2
    Electronic Resource
    Electronic Resource
    Septal innervation of mossy cells in the hilus of the rat dentate gyrus: an anterograde tracing and intracellular labeling study (1997)
    Springer
    Experimental brain research 114 (1997), S. 423-432 
    Details
    ISSN: 1432-1106
    Keywords: Key words Fascia dentata ; Mossy cells ; Interneurons ; Lucifer yellow ; Phaseolus vulgaris leucoagglutinin ; Septohippocampal projection ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Mossy cells in the hilus of the rat dentate gyrus are the main cells of origin of the dentate commissural and associational projections. They project along the septotemporal axis of the dentate gyrus and may thus influence the hippocampal signal flow in a longitudinal direction. To analyze the septal innervation of these hilar neurons, anterograde tracing with Phaseolus vulgaris leucoagglutinin (PHAL) was used in combination with intracellular labeling of mossy cells (Lucifer yellow). Anterogradely labeled septal fibers impinge on proximal and distal dendrites of hilar mossy cells but spare the cell body. In contrast, numerous aspiny hilar neurons, presumably GABAergic interneurons, receive a septal innervation on their somata and proximal primary dendrites. These data demonstrate that septal fibers show a specificity for the dendritic segments of hilar mossy cells. Since mossy cells project predominantly to adjacent hippocampal lamellae, the activity of adjacent portions of the dentate gyrus may be influenced by the septal input onto these neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00005651
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  • 3
    Electronic Resource
    Electronic Resource
    Hippocampal mossy fiber sprouting is not impaired in brain-derived neurotrophic factor-deficient mice (1998)
    Springer
    Experimental brain research 120 (1998), S. 399-402 
    Details
    ISSN: 1432-1106
    Keywords: Key words Neurotrophin ; Sprouting ; Dentate gyrus ; Mossy fibers ; Timm staining ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  In human temporal lobe epilepsy, a loss of hilar neurons followed by the sprouting of recurrent mossy fiber collaterals and the reinnervation of free synaptic sites on granule cell dendrites are discussed as possible mechanisms underlying hippocampal hyperexcitability. Dentate granule cells have been shown to upregulate brain-derived neurotrophic factor (BDNF) as well as TrkB, the high-affinity receptor for BDNF, in response to limbic seizures. This raised the possibility that BDNF is an important factor in hippocampal mossy fiber sprouting. Here we have used slice cultures of hippocampus, in which mossy fibers sprout and form a supragranular plexus in response to granule cell deafferentation, and have compared cultures from early postnatal BDNF-deficient mice and wild-type mice. We demonstrate that there is sprouting of supragranular mossy fibers in cultured slices from both BDNF knock-out and wild-type mice. We conclude that BDNF is not an essential factor for mossy fiber sprouting. However, our data do not exclude a role for BDNF in mossy fiber sprouting in wild-type mice, as compensatory mechanisms might have become effective in the mutant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050413
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  • 4
    Electronic Resource
    Electronic Resource
    Ultrastructure of mossy fiber endings in in vitro hippocampal slices (1981)
    Springer
    Experimental brain research 41 (1981), S. 247-255 
    Details
    ISSN: 1432-1106
    Keywords: Hippocampal slice ; Ultrastructure ; Mossy fiber synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 0.2 to 0.4 mm thick slices of guinea pig hippocampus were studied morphologically after varying periods of incubation at 36 ° C in Krebs-Ringer solution. Prior to fixation, the slices were tested for the presence of synaptically driven discharges of CA 3 neurons following mossy fiber (mf) stimulation because tissue preservation was satisfactory only in slices in which electrical responses were obtained. The fine structure of the mf layer in slices was compared with the ultrastructure of this region in hippocampal tissue fixed by transcardial perfusion or immersion of the tissue in the fixative. In the central part of the slices many intact neuronal structures of the mf layer could be seen even after 4 h of incubation. In the outer parts of the slices, neurons were swollen and vacuolated. These alterations were not observed in hippocampal tissue fixed by transcardial perfusion or by immersion. In all parts of the slices dark neurons and processes were found. Since dark neurons were also numerous in tissue blocks immersed in the fixative but were rare in perfused material, these changes were obviously caused by damage to unfixed tissue and fixation by immersion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238881
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  • 5
    Electronic Resource
    Electronic Resource
    Termination of cortical afferents on identified neurons in the caudate nucleus of the cat (1981)
    Springer
    Experimental brain research 41 (1981), S. 329-337 
    Details
    ISSN: 1432-1106
    Keywords: Caudate nucleus ; Golgi/EM ; Corticocaudate projection ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A combined Golgi/electron microscopic technique was used to investigate the fine structure and synaptology of Golgi-stained spiny neurons in the caudate nucleus of the cat. In order to study the termination sites of cortical afferents on Golgistained spiny neurons, cortical fibres were caused to degenerate by making extensive cortical lesions 3 days prior to fixation of the animals. When examined in the electron microscope, perikarya of labelled spiny neurons have a round nucleus, a few mitochondria and microtubules, and a poorly developed Golgi apparatus and rough endoplasmic reticulum. Only rarely are axo-somatic contacts seen. Labelled dendrites exhibit a moderate number of microtubules and sometimes elongated mitochondria. Numerous labelled spines are seen in the vicinity of their parent dendrites. They are contacted by smaller type I and type III boutons and larger type IV boutons (Hassler et al. 1978). Large boutons filled with clear round vesicles establish symmetric contacts with labelled dendritic shafts. Degenerating boutons of cortical afferents are seen in contact with spines and, more rarely, with dendritic shafts of Golgi-stained spiny neurons. All degenerating boutons synapsing with labelled structures are found some distance from the cell body. No contacts of degenerating cortical boutons with the soma or with stem dendrites of Golgi-stained spiny neurons are found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238890
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  • 6
    Electronic Resource
    Electronic Resource
    Transneuronal effects of entorhinal lesions in the early postnatal period on synaptogenesis in the hippocampus of the rat (1977)
    Springer
    Experimental brain research 30 (1977), S. 549-560 
    Details
    ISSN: 1432-1106
    Keywords: Hippocampus ; Synaptogenesis ; Entorhinal lesion ; Transneuronal effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The granule cell axons of the dentate gyrus (mossy fibers, MF) terminate with large, characteristic boutons on neurons of the regio inferior of the hippocampus. To study transneuronal effects on mossy fiber synaptogenesis, the entorhinal cortex, which is the source of the main afferent to the granule cells, was removed in 3-day old rats. After a postoperative survival time of 27 days, the animals were killed and the brain prepared for electron microscopy. No clear postlesional changes were observed in the inner structure of the presynaptic mossy fiber terminals. The mean size of MF boutons was roughly the same in the experimental animals as compared to normal, unoperated rats of the same age (4.19 μm2, SD 1.9; and 4.29 μm2, SD 2.2, respectively). On the postsynaptic side, however, some remarkable changes were found. In the operated animals, the number and total area of dendritic spines in synaptic contact with MF has significantly decreased in comparison with the controls. Also the size of a single spine in the operated animals was only 64 % of that in the normal. These changes were accompanied by a decrease in MF total perimeter and MF-dendritic contact length in the experimental animals. The length of the MF specialized synaptic contact was found to be correlated with the number and size of dendritic spines. Thus accordingly, though the length of the MF specialized contact with the dendritic shaft did not change, the absolute length of MF specialized contact with postsynaptic spines was decreased in the lesioned animals due to the numerical and size reduction of the spines. This suggests that normally functioning entorhinal afferents to the granule cells are necessary for the normal development of dendritic spines in contact with hippocampal mossy fibers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237644
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  • 7
    Electronic Resource
    Electronic Resource
    Heterogeneity in the Membrane Current Pattern of Identified Glial Cells in the Hippocampal Slice (1992)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 4 (1992), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Glial cells, acutely isolated or in tissue culture, have previously been shown to express a variety of voltage-gated channels. To resolve the question whether such channels are also expressed by glial cells in their normal cellular environment, we have applied the patch-clamp technique to study glial cells in hippocampal slices of 10–12-day-old mice. Based on the membrane current pattern, we distinguished four glial cell types. One was characterized by passive, symmetrical K+ currents activated in depolarizing and hyperpolarizing directions. A second population showed a similar current pattern, but with a marked decay of the current during the 50-ms voltage jumps. In a third population, the decaying passive currents were superimposed with a delayed rectifier outward current and, in some cases, with a slow inward current activated by depolarization. The fourth population expressed delayed rectifying outward currents, an inward rectifier K+ current and fast inward currents activated by depolarization. To unequivocally identify the glial cells we combined electrophysiological and ultrastructural characterizations. Therefore, cells were filled with the fluorescent dye lucifer yellow during characterization of their membrane currents, the fluorescence of the dye was used to convert diaminobenzidine to an electron-dense material, and subsequently slices were inspected in the electron microscope. Recordings were obtained from cells in the stratum radiatum and were identified as glial by their size, the characteristic chromatin distribution, and the lack of synaptic membrane specializations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1992.tb00897.x
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  • 8
    Electronic Resource
    Electronic Resource
    Recovery of ChAT lmmunoreactivity in Axotomized Rat Cholinergic Septal Neurons Despite Reduced NGF Receptor Expression (1997)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 9 (1997), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Previous studies have suggested that target-derived nerve growth factor (NGF) is essential for the survival of cholinergic basal forebrain neurons. Thus, axotomy of septohippocampal neurons in adult rats resulting in the withdrawal of target-derived NGF caused a dramatic loss of choline acetyltransferase (ChAT)-immunoreactive neurons in the medial septum-diagonal band complex. We have recently shown that this loss of immunolabelled neurons does not indicate cell death, since many septohippocampal cholinergic neurons recover their immunoreactivity for ChAT after a long survival time despite disconnection from target-derived neurotrophins. One possibility would be that these surviving ChAT-immunoreactive neurons have gained access to other, probably local, NGF sources. Here we provide evidence that the recovery of ChAT immunoreactivity after axotomy is not accompanied by a similar recovery of NGF receptor expression in these neurons. In situ hybridization for p75NTR mRNA and trkA mRNA 6 months after bilateral fimbria-fornix transection revealed a substantial loss of labelled cells. In addition, there was a persisting loss of p75NTR-immunoreactive and NGF-immunoreactive medial septal neurons. Cholinergic neurons in controls did not express NGF mRNA, but were heavily immunostained for NGF protein due to receptor-mediated uptake. These data suggest that at least some cholinergic septohippocampal neurons re-express ChAT either independently of NGF or with a reduced need for NGF.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1997.tb01488.x
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  • 9
    Electronic Resource
    Electronic Resource
    Ultrastructural localization of calcium in the myocardium of cardiomyopathic Syrian hamsters
    Amsterdam : Elsevier
    Journal of Molecular and Cellular Cardiology 20 (1988), S. 753-762 
    Details
    ISSN: 0022-2828
    Keywords: Calcium distribution ; Cardiomyopathic hamster ; Cytochemistry ; Mitochondria ; Sarcolemma
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0022-2828(88)80019-1
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  • 10
    Electronic Resource
    Electronic Resource
    GABAergic input of cholecystokinin-immunoreactive neurons in the hilar region of the rat hippocampus (1987)
    Springer
    Histochemistry and cell biology 86 (1987), S. 287-290 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Double immunostaining was performed for electron microscopy to analyze the synaptic connections between glutamate decarboxylase (GAD)-immunoreactive axons and cholecystokinin (CCK)-immunoreactive neurons in the hilar region of the rat hippocampal formation. Following immunostaining for CCK, the diaminobenzidine (DAB) reaction product was silver-intensified and gold-substituted. In a subsequent second immunostaining for GAD, the immunoreactive elements were labeled using a single DAB reaction. Electron microscopic analysis of the double-stained Vibratome sections demonstrated that the single DAB-labeled GAD-immunoreactive boutons form symmetrical synaptic connections on the soma and primary dendrites of the DAB-gold-labeled CCK-immunoreactive neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00490260
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