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  • 1
    Electronic Resource
    Electronic Resource
    The perineuronal net in the fastigial nucleus of the rat cerebellum (1984)
    Springer
    Anatomy and embryology 170 (1984), S. 79-85 
    Details
    ISSN: 1432-0568
    Keywords: Perineuronal net ; Astrocytes ; Fastigial nucleus ; Cerebellum ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The morphological study of the rat fastigial nucleus with the Golgi-Rio Hortega method showed the presence of glial perineuronal nets surrounding the large neurons, but not the small ones. This perineuronal net appeared as a mesh of tenuous glial processes which covers the neuronal perikarya and proximal dendrites. The small alveolate compartments in this mesh seem to correspond to the holes for the synaptic boutons. Our results also indicate that the perineuronal net is derived from interneuronal protoplasmic and velate astrocytes. Using camera lucida drawings of this perineuronal net we have made a quantitative estimation of the size and density of synaptic boutons on these large neurons. The average numerical density of synaptic boutons was about 19 per 100 μm2 of the neuronal surface, the mean area of the synaptic holes being 2.5 μm2. Furthermore, the quantitative data evidence that about 52.5% of the neuronal surface is presumably occupied by synaptic boutons whereas the remaining 47.5% is covered by the glial processes of the perineuronal net. Semithin sections prepared from thick Golgi sections were used for the cytological study of the neurons surrounded by this glial pericellular network. The possible functional significance of the perineuronal net in the regulation of synaptic transmission in the fastigial cerebellar nucleus is briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319461
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  • 2
    Electronic Resource
    Electronic Resource
    Number of nucleoli and coiled bodies and distribution of fibrillar centres in differentiating Purkinje neurons of chick and rat cerebellum (1995)
    Springer
    Anatomy and embryology 191 (1995), S. 359-367 
    Details
    ISSN: 1432-0568
    Keywords: Nucleoli ; Coiled bodies ; Nucleolar organizer regions ; Fibrillar centres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We used differentiating chick and rat Purkinje cells to investigate in homologous neurons the influence of the number of nucleolar organizer regions (two in the chick and six in the rat) on the behaviour of the nucleolus and coiled bodies. We employed specific silver-staining methods on smear preparations and on semithin and ultrathin sections. In chick Purkinje cells the number of nucleolar silver-staining granules increased from 15.7±3 (mean±SD) at embryonic day 13 to 23.8±3 at post-hatching day 7. These nucleolar granules were unevenly distributed between the two nucleoli of binucleolated cells. Electron-microscopic cytochemistry showed that nucleolar granules are equivalent to the fibrillar centres with their associated shell of dense fibrillar component. A reduction in the number of nucleoli was found during the differentiation of both chick and rat Purkinje cells, although in mature cells the average number of nucleoli per cell was higher in the chick (1.60) than in the rat (1.07). The number of coiled bodies decreased from 1.33 in newborn rats to 0.47 at postnatal day 90 in the rat. Coiled bodies were not observed in homologous chick Purkinje cells. The dynamic behaviour of nucleoli and coiled bodies during neuronal differentiation and the relationship of these two nuclear organelles with the number of nucleolar organizer regions is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00534689
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  • 3
    Electronic Resource
    Electronic Resource
    Cajal-Smirnow ansiform fibers in the molecular layer of the rat cerebellar cortex (1987)
    Springer
    Anatomy and embryology 176 (1987), S. 367-372 
    Details
    ISSN: 1432-0568
    Keywords: Cajal-Smirnow ansiform fibers ; Mossy fibers ; Axonal guidance ; Cerebellar cortex ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present light and electron microscopic study deals with the morphology and organization of Cajal-Smirnow ansiform fibers (AFs) in the molecular layer of the cerebellar cortex. The cerebella of normal adult rats were processed with Cajal's reduced silver method and conventional electron microscopy. With the silver method AFs appear as isolated elements or, more frequently, as small bundles of myelinated fibers, which emerge from the medullary rays, ascend through the granular, Purkinje cell and molecular layers and curve back to reenter the granular layer or cerebellar white matter. They traced an arciform trajectory of variable width and height in the molecular layer. Relatively large bundles of AFs were rarely found. The occurrence of AFs was confirmed in semithin sections as myelinated fibers of variable diameter ranging from 1 to 6 μm. Oligodendrocytes were often observed near AFs. At the ultrastructural level, the most common type of AF is large, with a relatively thin myelin sheath and a moderately dense axoplasm. Nodal or terminal synaptic differentiations were not observed. We suggest that AFs are misoriented cerebellar mossy fibers and their occurrence may be the consequence of a small-scale error in the axonal guidance of growing mossy fibers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310190
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  • 4
    Electronic Resource
    Electronic Resource
    Protein-synthesis inhibition induces perichromatin granule accumulation and intranuclear rodlet formation in osmotically stimulated supraoptic neurons (1993)
    Springer
    Anatomy and embryology 187 (1993), S. 363-369 
    Details
    ISSN: 1432-0568
    Keywords: Supraoptic nucleus ; Cell nucleus ; Perichromatin granules ; Nuclear inclusions ; Osmotic stimulation ; Cycloheximide ; Coiled body
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The distribution of perichromatin granules (PGs), a storage form of pre-mRNAs, was studied in supraoptic neurons of control and osmotically stimulated rats, and also after treatment with cycloheximide, a protein-synthesis inhibitor. In non-cycloheximide-treated rats, neuronal activation by dehydration significantly decreased the number of PGs. Conversely, PGs were drastically increased in the supraoptic neurons of dehydrated rats treated with cycloheximide for 4 h. This suggests that cycloheximide does not interfere with the transcriptional activation induced by dehydration, but it affects the processing of newly synthesized pre-mRNAs. Moreover, protein-synthesis inhibition was associated with the formation of intranuclear bundles of tubular filaments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185894
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  • 5
    Electronic Resource
    Electronic Resource
    Reactive gliosis of immature Bergmann glia and microglial cell activation in response to cell death of granule cell precursors induced by methylazoxymethanol treatment in developing rat cerebellum (1998)
    Springer
    Anatomy and embryology 198 (1998), S. 111-122 
    Details
    ISSN: 1432-0568
    Keywords: Key words Cerebellar cortex ; Apoptosis ; Brain macrophages ; Proliferating cell nuclear antigen ; Astroglial plasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The morphology, organization and expression of proliferating cell nuclear antigen (PCNA) and the cytoskeletal proteins vimentin and GFAP in immature Bergmann glial cells were studied after a developmental injury induced by a single dose of the cytotoxic agent methylazoxymethanol (MAM) administered on postnatal day 5. This drug, which produces cell death of cerebellar granule cell precursors, did not induce apoptosis in Bergmann glial cells, which are in a proliferative stage. After MAM treatment, PCNA staining showed a severe depletion of PCNA-positive granule cell precursors, whereas PCNA-positive Bergmann glial nuclei in the Purkinje cell layer were preserved. Moreover, the quantitative analysis revealed an increase in the density of both Purkinje cells and PCNA-positive Bergmann glial cells per mm of Purkinje cell layer in MAM-treated rats relative to age-matched controls, but the numerical ratio between these two cell populations remains invariable after MAM treatment. Vimentin and GFAP immunocytochemistry revealed a reinforcement of the Bergmann glial palisade with overexpression of both proteins and thicker immunoreactive glial processes in MAM-treated rats. At the ultrastructural level, Bergmann glial processes closely associated with dying cells in different stages of apopotosis were observed. Frequently, these processes enclosed dying cells in extracellular compartments. Furthermore, phagosomes containing apoptotic bodies were found in Bergmann fibers of MAM-treated rats. These data indicate that the cell death of granule cell precursors triggers a reactive response in immature Bergmann glia. We suggest that this response reflects the plasticity of Bergmann glia to control the neuronal microenvironment in the maturing molecular layer, protecting healthy cells against the potentially harmful contents of dying cells. In situ labeling of cell death with the TUNEL method revealed that the cell death of granule cell precursors is of the apoptotic type. The participation of ameboid microglial cells in the phagocytosis of apoptotic cells was shown with tomato lectin histochemistry and ultrastructual analysis. Moreover, the presence of mitosis in this microglial population demonstrates its proliferative activity in regions of extensive cell death.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050169
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  • 6
    Electronic Resource
    Electronic Resource
    Creutzfeldt-Jakob disease with severe involvement of cerebral white matter and cerebellum (1990)
    Springer
    Virchows Archiv 417 (1990), S. 533-538 
    Details
    ISSN: 1432-2307
    Keywords: Creutzfeldt-Jakob disease ; Cerebellar de-generation ; Leucoencephalopathy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We describe a patient with Creutzfeldt-Jakob disease (CJD) of the ataxic and panencephalopathic type. Postmortem examination revealed the characteristic lesions of CJD in the grey matter and profound white matter involvement was seen with immunocytochemical techniques. Ultrastructural white matter lesions were identical to those described in experimentally transmitted CJD. There was marked loss of cerebellar granule cells with virtual disappearance of parallel fibres, but Purkinje cells were only slightly reduced. Electron microscopic studies revealed extensive degenerative changes including cytoplasmic vacuoles in both cell types. Silver methods disclosed massive impregnation of white matter and striking abnormalities of Purkinje cells consisting of hypertrophy and flattening of thick dendritic branches, reduction in the number of terminal branchlets, segmentary loss of spines and polymorphic spines. These findings show the extensive involvement of all three cerebellar cortical layers and the reactive plasticity of Purkinje cells to deafferentiation. They favour the hypothesis that demyelination represents a primary lesion of the white matter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01625735
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  • 7
    Electronic Resource
    Electronic Resource
    Interactions between astroglia and ectopic granule cells in the cerebellar cortex of normal adult rats: a morphological and cytochemical study (1990)
    Springer
    Experimental brain research 80 (1990), S. 397-408 
    Details
    ISSN: 1432-1106
    Keywords: Cerebellar cortex ; Ectopic granule cells ; Astrocytes ; Bergmann glia ; Neuron-astroglia interactions ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cytology and organization of astroglial cells associated with ectopic granule cells (EGCs) have been studied in the cerebellar cortex of normal adult rats, using Golgi preparations, immunohistochemistry against the glial fibrillary acidic protein (GFAP) and ultrastructural analysis. Elongated perikarya of EGCs scattered in the molecular layer were usually attached to radial Bergmann fibers, which exhibited a normal morphology. A second configuration of EGCs consisted of intrafissural colonies of ectopic neurons. The molecular layer that surrounded these ectopic colonies showed disorientation of both Bergmann fibers and parallel fibers. Within the ectopic tissue, typical velate astrocytes were commonly observed. They formed homologous associations with EGC perikarya and cerebellar glomeruli. However, a restricted astroglial plasticity was detected in the form of heterologous interactions between astrocytes and Purkinje cell dendrites, including their associated synapses with parallel fibers. In spite of this astroglial plasticity, our results suggest that in the physiological systems of granule cell ectopia studied here, the different specific interactions of Bergmann glia and astrocytes with neurons tend to be conserved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228167
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  • 8
    Electronic Resource
    Electronic Resource
    Schwann cell nuclear remodelling and formation of nuclear and coiled bodies in Guillain-Barré syndrome (1996)
    Springer
    Acta neuropathologica 92 (1996), S. 386-394 
    Details
    ISSN: 1432-0533
    Keywords: Key words Guillain-Barré syndrome ; Nuclear bodies ; Coiled bodies ; Nuclear size ; Schwann cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have examined the reorganization of the cell nucleus in myelin-related Schwann cells (SCs) in a case of acute Guillain-Barré syndrome (GBS). Spinal root samples of the GBS case and human controls were processed for light and electron microscopy. The cytochemical EDTA method for ribonucleoproteins (RNPs) and a specific silver staining technique for nucleolar organizer regions were used on ultrathin sections. In SCs of the GBS case, we observed a significant increase in nuclear size (64.99 ± 10.47 μm2 in the GBS vs 35.07 ± 8.74 μm2 in the controls mean ± SD) accompanying partial decondensation of heterochromatin domains and elaboration of an extensive network of RNP-containing perichromatin fibrils. In addition, the formation of two types of nuclear structures, coiled bodies and nuclear bodies of Bouteille, was induced in SCs of the case of acute GBS. Free coiled bodies were observed in the nucleoplasm and were characteristically stained with both RNP and silver procedures. Typical “simple” and “complex” nuclear bodies were regularly found, sometimes in association with coiled bodies. On the basis of cell nucleus physiology, all of these changes are considered cytological indicators of enhanced transcription and cellular hyperactivity, and they seem to reflect a reactive response of SCs triggered by the constellation of cellular and humoral signals associated with acute GBS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050534
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  • 9
    Electronic Resource
    Electronic Resource
    Regulation of Schwann cell numbers in tellurium-induced neuropathy: apoptosis, supernumerary cells and internodal shortening (1998)
    Springer
    Acta neuropathologica 95 (1998), S. 269-279 
    Details
    ISSN: 1432-0533
    Keywords: Key words Schwann cell ; Apoptosis ; Supernumerary cells ; Internodal shortening ; Tellurium neuropathy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have used an experimental model of tellurium(Te)-induced demyelinating neuropathy in the rat to study cellular mechanisms involved in regulating Schwann cell (SC) numbers during remyelination. Starting at postnatal day 21, weaned rats were fed a diet containing 1.1% elemental Te. Following 7 days of Te treatment and at several time points of post-tellurium treatment (PTe), the animals were processed for ultrastructural analysis, SC nuclei quantification and teased fibre preparations. It is well-established that Te induces a transient demyelinating/remyelinating sequence in sciatic nerves. The loss of the myelin sheath in this neuropathy produces active proliferation and overproduction of immature SCs. By electron microscopy analysis most mitotic SCs were located along demyelinated segments. Quantitative determination of SC nuclei per transverse section of sciatic nerve revealed a dramatic increase of SCs at 2 days PTe relative to control nerves. The number of SC nuclei then decreased progressively during the long-term period of recovery studied (330 days PTe). In Te-treated rats, SCs undergoing cell death were regularly found within the nerve fibre compartment, especially on demyelinated segments. Dying cells exhibited morphological features of apoptosis and appeared enclosed by lamellar processes of adjacent healthy SCs in extracellular compartments. Both healthy immature SCs and endoneurial macrophages were involved in the phagocytosis of apoptotic SCs. Particularly during remyelination, supernumerary endoneurial SCs were observed surrounding myelinated fibres. These cells progressively became atrophic with a morphological phenotype similar so that of “onion bulb” cells. On the other hand, teased fibre measurements revealed a remarkable permanent internodal shortening in remyelinated fibres from Te-treated sciatic nerves. These results indicate that a portion of redundant immature SCs are susceptible to elimination by apoptosis. However, other distinct biological mechanisms such as the persistence of supernumerary SCs in the endoneurium and the shortening of internodal lengths are also involved in regulating SC numbers during the remyelination stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050797
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  • 10
    Electronic Resource
    Electronic Resource
    Activation of the autophagy, c-FOS and ubiquitin expression, and nucleolar alterations in Schwann cells precede demyelination in tellurium-induced neuropathy (1999)
    Springer
    Acta neuropathologica 97 (1999), S. 143-155 
    Details
    ISSN: 1432-0533
    Keywords: Key words Schwann cell ; Early intermediate genes ; Endoplasmic reticulum ; Macroautophagy ; Nucleolus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have used an experimental model of tellurium (Te)-induced demyelinating neuropathy in the rat to study cellular mechanisms involved in the early response of myelinating Schwann cells (SCs) to injury, prior to demyelination. Starting at postnatal day 21, weaned rats were fed a diet containing 1.1% elemental Te. The animals were killed daily within the 1st week of Te diet and the sciatic nerves were processed for the ultrastructural and immunocytochemical studies. Immunohistochemistry revealed that Te induces an increased nuclear expression of c-Fos in SCs. By electron microscopy analysis, the early cytoplasmic alteration was a dramatic disorganization of the rough endoplasmic reticulum (ER) with cisternal dilations and redistribution and loss of membrane-bound ribosomes. This was followed by a prominent activation of the macroautophagy in SCs. This process involved the formation of autophagosomes containing well-preserved cell organelles, autolysosomes with cellular remnants in various phases of degeneration and lysosomes. Te treatment also induced the expression of free ubiquitin in the perikaryal region of the SC cytoplasm. Immunogold electron microscopy showed the subcellular distribution of ubiquitin in the cytosol, around of dilated ER cisterns and in the matrix of autolysosomes and residual bodies. At the nucleolar level, fibrillarin immunofluorescence revealed nucleolar segregation in SCs exposed to Te. The ultrastructural study confirmed the segregation of the nucleolar components with a peripheral distribution of the dense fibrillar component. These results support the hypothesis that the depletion of cholesterol induced by Te treatment triggers a stress response in myelinating SCs mediated by immediate early genes of the fos family. The cellular response includes a severe disruption of the protein synthesis machinery, namely the rough ER and nucleolus, with the subsequent activation of both ubiquitin and autophagic pathways of proteins and cell organelle degradation. This cytoplasmic remodeling may represent a cytoprotective mechanism in the response of SCs to a neurotoxic stress. Furthermore, it must be a prerequisite for the induction of phenotypic changes and cell repair mechanisms in SCs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050967
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