| Postnatal changes in the numerical density and total number of asymmetric and symmetric synapses in the hypoglossal nucleus of the rat. | |
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MedLine Citation:
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PMID: 9693795 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Morphometric analyses were performed to investigate the progressive and regressive phases of synaptogenesis in the hypoglossal nucleus of the rat during normal postnatal development. The total volume of the hypoglossal nucleus and both the numerical density (NV, contacts per mm3) and total number of synapses were measured at 5-day intervals from birth to postnatal day 30 and in young adults. Values of NV were calculated separately for asymmetric and symmetric synapses as well as for axospinous, axodendritic and axosomatic contacts. The volume of the hypoglossal nucleus increased significantly from birth to postnatal day 30 (414%) with no further increase in the adult. The NV of all synapses increased significantly from birth to day 20 (131%), followed by a significant decreases in adults (45%). The total number of synapses increased significantly from birth to day 20 (843%), followed by a significant decrease in adults (30%). Similar developmental changes in density and total number were observed for asymmetric and symmetric synapses. The magnitude of synapse elimination, occurring after day 20, was approximately 30% for both morphological types. During postnatal development the vast majority of synapses in the hypoglossal nucleus were found to form axodendritic contacts (85-95%). Synapse elimination was observed for axospinous, axodendritic and axosomatic contacts. These findings indicate that the progressive and regressive phases of synaptogenesis occur earlier in the hypoglossal nucleus than in the cerebral cortex of the rat, suggesting a caudal-to-rostral gradient. Synapse elimination was not restricted on the basis of morphological type or postsynaptic target site. |
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Authors:
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J R O'Kusky |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Brain research. Developmental brain research Volume: 108 ISSN: 0165-3806 ISO Abbreviation: Brain Res. Dev. Brain Res. Publication Date: 1998 Jun |
Date Detail:
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Created Date: 1998-10-21 Completed Date: 1998-10-21 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 8908639 Medline TA: Brain Res Dev Brain Res Country: NETHERLANDS |
Other Details:
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Languages: eng Pagination: 179-91 Citation Subset: IM |
Affiliation:
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Department of Pathology, University of British Columbia, Vancouver, Canada. jrokusky@unixg.ubc.ca |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Age Factors Animals Hypoglossal Nerve / cytology*, growth & development* Microscopy, Electron Neurons / ultrastructure Rats Rats, Sprague-Dawley Synapses / physiology*, ultrastructure* |
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