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  • 1
    Electronic Resource
    Electronic Resource
    Vertical bundles of dendrites in the neocortex (1972)
    Springer
    Anatomy and embryology 136 (1972), S. 213-223 
    Details
    ISSN: 1432-0568
    Keywords: Neocortex ; Dendrites ; Columns ; Rabbit ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In frontal and tangential paraffin sections through the sensory-motor cortex of the rabbit, vertical bundles of dendrites have been found. Each bundle consists of several apical dendrites of layer V pyramids and extends through layer IV into layer III/II where the dendrites begin to ramify. Electron microscopy reveals that within the bundle some of the dendrites approach each other so closely as to be separated by the extracellular space only. A vertical bundling of dendrites has, also been found in various regions of the sensory-motor cortex of the cat. — The hypothesis is put forward that the vertical bundles of dendrites are the morphological substrate of the vertical functional units deduced from electrophysiological observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00519179
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  • 2
    Electronic Resource
    Electronic Resource
    Functional changes of the neuronal and glial elements at the surface of the external layer of the median eminence (1974)
    Springer
    Anatomy and embryology 143 (1974), S. 255-262 
    Details
    ISSN: 1432-0568
    Keywords: Median eminence ; Neuro-vascular contacts ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The vascular surface of the external layer of the median eminence is composed of neuronal and glial processes. Neuro-vascular contacts are supposed to be necessary for the release of hypophysiotropic neurohormones. The present study confirms the hypothesis that the relative extent of neuro-vascular and glio-vascular contacts varies under different functional conditions of the tubero-hypophysial system. Morphometric analysis shows that in normal rats about 20% of the surface is lined by neuro-vascular contacts. After bilateral adrenalectomy the neuro-vascular contacts are enlarged to 40% whereas application of an extract of stalk-median eminence tissue is followed by a decrease of the neuro-vascular contacts to 15%. The implications of these results are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00519869
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  • 3
    Electronic Resource
    Electronic Resource
    Changes of extent of Neuro-vascular contacts and number of neuro-glial synaptoid contacts in the pituitary posterior lobe of dehydrated rats (1974)
    Springer
    Anatomy and embryology 146 (1974), S. 157-165 
    Details
    ISSN: 1432-0568
    Keywords: Neurohypophysis ; Neuro-vascular contacts ; Neuro-glial synaptoid contacts ; Dehydration ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The posterior lobe of the hypophysis consists of neurosecretory nerve fibres and glial cells, both abutting on the perivascular space of sinusoidal capillaries. Nerve fiberes and glial cells are connected with each other by a high number of synaptoid contacts. Several ultrastructural changes following dehydration have been described by other authors. This study presents the data of some morphometric investigations on normal and dehydrated rats. The relative extent of neuro-vascular contacts is not contstant; it increases significantly from 52 (±2.8)% in normal rats to 67(±1.2)% in rats with a dehydration time of 3 days. Correspondingly the extent of glio-vascular contacts is diminished. In addition, water-deprived animals show a clear increase in the number of neuro-glial synaptoid contacts with 3.1 (±0.4) per square unit nervous tissue compared to 2.1 (±0.3) per Square unit in untreated controls. These results indicate a dynamic motility of neuronal and glial elements depending on functional conditions, as was found for the external layer of the median eminence. Furthermore there seems to be a relationship between secretory activity and the number of neuroglial synaptoid contacts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315592
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  • 4
    Electronic Resource
    Electronic Resource
    Rearrangement of the retino-collicular projection after partial optic nerve crush in the adult rat (2004)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 19 (2004), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The establishment of retino-collicular topography is a well-investigated model of axon pathfinding and it was believed that this topography is irreversibly fixed throughout life. We now report that, after partial crush of the adult rat optic nerve, the anterograde transport of intravitreally-injected tracers via axons of surviving retinal ganglion cells (RGC) in all retinal quadrants is confined to the rostro-medial part of the superior colliculus (SC). This indicates that the retino-collicular topography is rearranged after partial crush of the adult rat optic nerve. The reorganization starts in the injured optic nerve where surviving axonal fibres are demyelinized and bundled in the periphery of the optic nerve distal to the crush site. This is followed by a displacement of surviving axons to the medial part of the optic tract (OT) within 2 weeks. The infiltration of macrophages with the subsequent production of tumour necrosis factor-α at the lesion site is a prerequisite for the altered retino-collicular projection as blockade of tumour necrosis factor-α signalling with the neutralizing antibody Infliximab abolishes reorganization in the SC and lateralization of RGC axons in the optic nerve and OT. This suggests that optic nerve inflammation is necessary for a progressive bundling of surviving RGC axons, probably via clearance of cellular debris which, in turn, may lead to a redistribution of RGC axons to the medial OT and rostro-medial SC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.2004.03087.x
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  • 5
    Electronic Resource
    Electronic Resource
    Expression and functional characterization of the mt1 melatonin receptor from rat brain in Xenopus oocytes: evidence for coupling to the phosphoinositol pathway (2001)
    Copenhagen : Munksgaard International Publishers
    Journal of pineal research 30 (2001), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Melatonin-sensitive receptors were expressed in Xenopus laevis oocytes following an injection of mRNA from rat brain. The administration of 0.1–100 μmol/L melatonin to voltage-clamped oocytes activates calcium-dependent chloride currents via a pertussis toxin-sensitive G protein and the phosphoinositol pathway. To determine which melatonin receptor type (mt1, MT2, MT3) is functionally expressed in the Xenopus oocytes, we used (i) agonists and antagonists of different receptor types to characterize the pharmacological profile of the expressed receptors and (ii) a strategy of inhibiting melatonin receptor function by antisense oligonucleotides. During pharmacological screening administration of the agonists 2-iodomelatonin and 2-iodo-N-butanoyl-5-methoxytryptamine (IbMT) to the oocytes resulted in oscillatory membrane currents, whereas the administration of the MT3 agonist 5-methoxycarbonylamino-N-acetyltryptamine (GR135,531) exerted no detectable membrane currents. The melatonin response was abolished by a preceding administration of the antagonists 2-phenylmelatonin and luzindole but was unaffected by the MT3 antagonist prazosin and the MT2 antagonist 4-phenyl-2-propionamidotetralin (4-P-PDOT). In the antisense experiments, in the control group the melatonin response occurred in 45 of 54 mRNA-injected oocytes (83%). Co-injection of the antisense oligonucleotide, corresponding to the mt1 receptor mRNA, caused a marked and significant reduction in the expression level (13%; P〈0.001). In conclusion, the results demonstrate that injection of mRNA from rat brain in Xenopus oocytes induced the expression of the mt1 receptor which is coupled to the phosphoinositol pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-079X.2001.300302.x
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  • 6
    Electronic Resource
    Electronic Resource
    Alterations of neuronal fibers after epileptic activity induced by pentylenetetrazole: fine structure investigated by calcium cytochemistry and neurobiotin labeling (buccal ganglia, Helix pomatia) (1996)
    Springer
    Cell & tissue research 286 (1996), S. 43-53 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Epilepsy ; Dendrites ; Degenerative changes ; Endoplasmic reticulum ; Calcium-binding sites ; Helix pomatia (Mollusca)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The influence of epileptic activity on both the fine structure of neuronal processes and the subcellular distribution of calcium-binding sites was investigated in an epileptic model system, the buccal ganglion of Helix pomatia. Pentylenetetrazole was used to induce epileptic activity. Calcium-binding sites were visualized as electron-dense precipitates. Epileptic and control activity was intracellularly recorded from neuron B3 labeled with neurobiotin. After epileptic treatment, many processes contained vacuolated or electron-lucent areas next to morphologically intact areas. Most of these areas were enveloped by layers of endoplasmic reticulum. Lamellar formations of membranes occurred frequently. Calcium cytochemistry revealed a high content of dense precipitates within these formations of the endoplasmic reticulum. Local accumulations of diffuse precipitates were more frequent after epileptic activity than in controls. In contrast, structures such as lamellar bodies, cytosomes, and synapse-like formations, all of which contained many electron-dense precipitates, were apparently unchanged after epileptic activity. This study demonstrates that epileptic activity can lead to local degeneration of neuronal fibers and an associated increase in calcium-binding sites. It is suggested that calcium sequestration is locally increased within neuronal processes during epileptic activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050673
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  • 7
    Electronic Resource
    Electronic Resource
    Changes in TSH-immunoreactivity in the pars tuberalis and pars distalis of the fetal rat hypophysis following maternal administration of propylthiouracil and thyroxine (1990)
    Springer
    Cell & tissue research 260 (1990), S. 403-408 
    Details
    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Pars tuberalis ; Immunocytochemistry ; Thyroid-stimulating hormone (TSH) ; Propylthiouracil (PTU) ; Thyroxine (T4) ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pars tuberalis (pt) of the adenohypophysis is unique in its close spatial relationship to the neurohemal contact area of the median eminence. The morphology of pt-specific secretory cells does not resemble cell types of the pars distalis (pd); the functional role of these cells within the endocrine system is still unknown. One group of young mature female Wistar rats received propylthiouracil (PTU), a second group thyroxine (T4) (10 mg/l each in drinking water) from about 3 weeks prior to the expected pregnancy and throughout the experiment. On gestation day 20, the fetuses were obtained by laparatomy. Serial sections from the rostral portion of the pt and from the pd were immunostained using the peroxidase-antiperoxidase method. TSH concentrations were determined by RIA in serum and pituitaries; T4 was measured in serum. An antiserum against rat (r) TSH revealed a moderate positive reaction of nearly all cells of the pt in the control group. In both experimental groups the pt-specific cells showed weak or no immunoreactivity. Sections of all groups were negative with anti(r)-LH,-GH,-PRL. In contrast to controls, only a few immature TSH-cells could be found in sections of the pd in the T4-group, while concentrations of TSH in blood and hypophysis were very low. TSH-cells in the PTU-group were enlarged and less intensely stained. TSH-concentrations were decreased in the hypophysis, blood levels were elevated. All sections of the pd-specific cell populations showed positive immunoreactions with anti(r)-LH,-GH,-PRL. The present results suggest that pt-specific secretory cells of the fetal rat possess TSH immunoreactivity but do not resemble the thyrotropes of the pd. Marked differences in immunoreactivity displayed by the experimental groups indicate that pt-specific cells respond to changes in the fetal thyroid status and are a component of the thyroid-regulating system in addition to the thyrotropes of the pd. This novel aspect of pt function is discussed in connection with recent results concerning melatonin receptors found in the pt and the inhibitory influence of the pineal gland exerted on the thyroid gland.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318643
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of photoperiod on the ultrastructure of the hypophysial pars tuberalis of the Djungarian hamster, Phodopus sungorus (1984)
    Springer
    Cell & tissue research 238 (1984), S. 213-216 
    Details
    ISSN: 1432-0878
    Keywords: Photoperiods ; Pituitary gland, pars tuberalis ; Ultrastructure ; Phodopus sungorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Conspicuous cytological differences are found between specific secretory cells of the hypophysial pars tuberalis of Djungarian hamsters exposed to long and short photoperiods. The cells differ with respect to the shapes of perikarya and nuclei and show diverse amounts of secretory granules, lysosome-like bodies and glycogen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215166
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