Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Acute osmotic/stress stimuli induce a transient decrease of transcriptional activity in the neurosecretory neurons of supraoptic nuclei (1998)
    Springer
    Journal of neurocytology 27 (1998), S. 205-217 
    Details
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Administration of hypertonic NaCl solutions by intraperitoneal injection evokes a transient expression of immediate-early genes in the hypothalamic magnocellular neurons of supraoptic nuclei (SON), which is followed by an upregulation of arginine vasopressin synthesis and a general increase in cellular metabolic activity. Here we have analysed the changes that occur in the nucleus of SON neurons during the period of transient Fos expression after injection of hypertonic saline. Within the first 30 minutes after injection, the nuclei become significantly smaller, contain more condensed chromatin and incorporate less 3H-uridine than the controls. By 12 hours these effects are reverting and at 24 hours the nuclei are already more active than the controls. Additionally, we observe an initial decrease in the number of coiled bodies per nucleus within the first 2 hours, followed by a 3-fold increase at 24 hours after injection. As coiled bodies are transcription-dependent subnuclear 'organelles', these results further support the view that injection of hypertonic saline causes a transient inhibition of nuclear activity. Our data show that SON neurons respond to acute osmotic/stress stimuli first with inhibition and then with activation of gene expression. Importantly, inhibition of transcriptional activity occurs simultaneously with maximal accumulation of Fos protein in the nucleus, raising the possibility that activation of c-fos expression may cause repression of target genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006937032068
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Apoptosis induced by methylazoxymethanol in developing rat cerebellum: organization of the cell nucleus and its relationship to DNA and rRNA degradation (1997)
    Springer
    Cell & tissue research 289 (1997), S. 25-38 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Cell death ; Cerebellar granule cells ; Chromatin ; Nucleolus ; Dispersed ribosomes ; DNA ladder ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. We present a cytological and biochemical study of the cell death of granule cell precursors in developing rat cerebellum following treatment with the cytotoxic agent methylazoxymethanol (MAM) during the first postnatal week. The density of apoptotic figures per square millimeter progressively increases after 6, 12, 24 and 44 h of treatment, whereas cells immunoreactive for proliferating cell nuclear antigen tend to disappear in the external granular layer (EGL). DNA migration on gel electrophoresis reveals a typical ladder pattern of internucleosomal cleavage following MAM treatment, whereas gel electrophoresis of rRNA shows a conspicuous degradation of both 28S and 18S rRNAs. Ultrastructural analysis has revealed the alterations of structures containing chromatin and ribonucleoprotein (RNP) in dying cells of the EGL. The typical granular beaded configuration of the condensed chromatin changes to a denser, more homogeneous texture suggesting nucleosomal disruption. The reorganization of RNP nuclear domains is reflected by the appearance of dispersed nucleoplasmic RNP particles and the formation of a coiled-body-like structure. However, typical nuclear domains involved in the splicing of RNAs, namely interchromatin granule clusters and typical ”coiled bodies”, are not found in apoptotic cells. Intranuclear bundles of filaments have also been detected. In the cytoplasm, the presence of dispersed single ribosomes is an initial sign of apoptosis. The massive dispersion and disruption of ribosomes detected after 24 h and 44 h of MAM treatment is reflected by the degradation of both 28S and 18s rRNAs. These results show that MAM treatment provides a useful experimental model for the study of apoptosis in the developing central nervous system. The organization of the cell nucleus in cells undergoing apoptosis clearly reflects a disruption of the nuclear compartments involved in transcription and the processing and transport of RNA and is related to the patterns of DNA and rRNA degradation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050849
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...