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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructural characterization of the postnatal development of the thalamic ventrobasal and reticular nuclei in the rat (1996)
    Springer
    Anatomy and embryology 193 (1996), S. 341-353 
    Details
    ISSN: 1432-0568
    Keywords: Thalamus ; Somatosensory system ; Synaptogenesis ; Nervous system ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Electron microscopy has been employed to analyze the normal maturationai sequence that characterizes the postnatal development of synaptic circuits in the ventrobasal (VB) and reticular (Rt) thalamic nuclei of rats at different ages (from birth to the end of the third postnatal week). Throughout the first postnatal week, similar signs of immaturity are observed in both nuclei, mainly consisting in scarcity of cytoplasmic organelles, presence of wide extracellular spaces, and absence of myelinated fibers. Several synaptic terminals are however present from birth, thus indicating that some of the afferents have already reached and contacted their thalamic target during embryonic life. Most of the terminals are small and contain only a few round, clear vesicles, and therefore their cytological features do not allow the identification of their origin. In particular, in both nuclei, terminals with flat vesicles and symmetric specialization are only rarely observed, and in VB the ascending terminals are not distinguishable from terminals of other sources as they are in adults. During the second postnatal week, progressive maturationai changes in VB and Rt lead to neurons having well-developed cytoplasmic organelles and to an elaborate neuropil containing myelinated fibers and synaptic terminals that are morphologically heterogeneous and resemble the adult ones. The permanence of growth cone-like profiles and of numerous somatic and dendritic protrusions, often contacted by synaptic terminals, indicates that a certain degree of reorganization is still taking place in both nuclei. By the end of the third postnatal week the synaptic organization of VB and Rt is indistinguishable from that observed in adults. This ultrastructural study shows that the appearance of the neuropil of VB and Rt and the morphological complexity of the synaptic arrangements characteristic of the adult rat are not present in neonates, but are gradually acquired during the first three postnatal weeks, and that they result from progressive modifications in circuit organization involving both pre- and postsynaptic elements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00186691
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Immunocytochemical demonstration of neurotransmitters in the nerve plexuses of the foot and the anterior byssus retractor muscle of the mussel, Mytilus galloprovincialis (1990)
    Springer
    Cell & tissue research 261 (1990), S. 467-476 
    Details
    ISSN: 1432-0878
    Keywords: Serotonin (5-HT) ; Substance P ; GABA ; Immunocytochemistry ; Invertebrate peripheral nervous system ; Mytilus galloprovincialis (Mollusca)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunocytochemical methods were applied to study the distribution of putative neurotransmitters (5-HT, substance P, GABA, glutamate and aspartate) in the nerve plexuses of the foot and the anterior byssus retractor muscle (ABRM) of Mytilus galloprovincialis (Mollusca, Bivalvia). The foot presents extensive nerve plexuses containing 5-HT and substance P-like immunoreactive material with a similar distribution beneath the surface epithelium, around the vessels and in the glandular regions. Coexistence of the two putative neurotransmitters was observed in a few nerve fibers, Conversely, muscle fibers, both in the foot and in the ABRM, are innervated only by 5-HT-positive fibers, while substance P-like material is present only in the networks of the ABRM epimysial sheath. Immunoreactivity for glutamate and aspartate was not demonstrated, while rare GABA-positive nerve cells and fibers were found only in the foot. The results of this investigation provide a morphological background to previous physiological studies on 5-HT in the nervous system of bivalve molluscs. Moreover, they confirm that the nervous system of Mytilus contains a remarkable amount of a substance related to the vertebrate tachykinin family.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00313525
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    Paper (German National Licenses)
    Fulltext
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