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.CITAZIONEcosa sono le cellule unipolari a spazzola e dove si trovano?
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devo provare a rispondere a questa, non la ho ancora prenotata . -
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Per il momento ho trovato questo
cellule unipolari a spazzola. -
Foster83.
User deleted
Mai sentite.... . -
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cellule a spazzola unipolari, un elemento cellulare del circuito corticocerebellare fino ad ora pochissimo conosciuto, dimostrando per la prima volta che esse costituiscono un sistema attivato dalle afferenze muscoidi, che possiede azione eccitatoria mediata dal glutammato, su cui convergono fibre provenienti da strutture extracerebellari come i recettori vestibolari.
(fonte: http://66.102.9.104/search?q=cache:WXd9uFY...lient=firefox-a ). -
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Bisognerebbe trovare qualche microfotografia o qualche disegno.
A pag. 9 di questo link parla delle fibre muscoidi
afferenze muscoidi. -
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dalla tabella che ho pubblicato sul mio sito:
CELLUEL A SPAZZOLA: chiamate anche brush cells. cellule epiteliali di forma cilindrica, presenza di un orletto a spazzola costituito da microvilli lunghi circa 3 um. si pensa abbiano funzione recettoriale per la presenza di terminazioni nervose
(fonte: http://www.tursiops-biology.com/i_200_tipi_di_cellule.htm )
Forse ci siamo:
Unipolar brush cells are a distinct class of excitatory interneurons situated in the granular layer of the cerebellar cortex, where they form giant synapses with individual mossy fiber terminals. We have previously shown that primary cerebellar cell cultures from embryonic and postnatal rodents contain neurons displaying morphological and chemical phenotypes characteristic of unipolar brush cells in situ, including intense staining with calretinin antiserum.
(fonte: http://www.springerlink.com/content/8ej9mhqk7cw76nvc/ )
Ancora:
Unipolar brush cells are a class of interneurons in the granular layer of the mammalian cerebellum that receives excitatory mossy fiber synaptic input in the form of a giant glutamatergic synapse. Previously, it was shown that the unipolar brush cell axon branches within the granular layer, giving rise to large terminals. Single mossy fiber stimuli evoke a prolonged burst of firing in unipolar brush cells, which would be distributed to postsynaptic targets within the granular layer. Knowledge of the ultrastructure of the unipolar brush cell terminals and of the cellular identity of its postsynaptic targets is required to understand how unipolar brush cells contribute to information processing in the cerebellar circuit. To investigate the unipolar brush cell axon and its targets, unipolar brush cells were patch-clamped in fresh parasagittal slices from rat cerebellar vermis with electrodes filled with Lucifer Yellow and Biocytin, and examined by confocal fluorescence and electron microscopy. Biocytin was localized with diaminobenzidine chromogen or gold-conjugated, silver-intensified avidin. Light microscopic examination revealed a single thin axon emanating from the unipolar brush cell soma that gave rise to 2-3 axon collaterals terminating in mossy fiber-like rosettes in the granular layer, typically within a few hundred μm of the soma. In some cases, axon collaterals crossed the white matter within the same folium before terminating in the adjacent granular layer. Electron microscopic examination of serial ultrathin sections revealed that proximal unipolar brush cell axons and axon collaterals were unmyelinated and devoid of synaptic contacts. However, the rosette-shaped enlargements of each collateral formed the central component of glomeruli where they were surrounded by dendrites of granule cells and/or other unipolar brush cells, with which they formed asymmetric synaptic contacts. A long-latency repetitive burst of polysynaptic activity was observed in granule cells in this cerebellar region following white matter stimulation. The unipolar brush cell axons, therefore, form a system of cortex-intrinsic mossy fibers. The results indicate that synaptic excitation of unipolar brush cells by mossy fibers will drive a large population of granule cells, and thus will contribute a powerful form of distributed excitation within the basic circuit of the cerebellar cortex.
(fonte: http://cat.inist.fr/?aModele=afficheN&cpsidt=1460015 )
e per finire (dopo di che dovrò tradurre per riassumere il tutto):
The unipolar brush cell (UBC) is a novel type of small neuron that is characterized by sets of morphological and chemical phenotypes. UBCs occur in the granular layer of the mammalian cerebellar cortex, particularly in folia of the vestibulocerebellum, and in the granule cell domains of the dorsal cochlear nucleus. The UBC is characterized by a single dendrite that terminates with a brush-like tip of dendrioles. The soma, the dendritic stem, and especially the dendrioles emit short, non-synaptic appendages. The dendrioles represent the main synaptic apparatus of the UBC and articulate tightly with a single mossy fiber rosette forming a glomerular array characterized by an extraordinarily extensive synaptic contact. Electron microscopic and electrophysiological observations indicate that the unusual synaptic ultrastructure may produce entrapment of neurotransmitter in the synaptic cleft. While ionotropic glutamate receptors are enriched in correspondence of the postsynaptic density, metabotropic glutamate receptors are situated extrasynaptically and are particularly enriched at the appendages, which usually do not bear synaptic junctions. Some of the UBCs receive their input from choline acetyltransferase-positive mossy rosettes originating from the vestibular nuclei, suggesting that ACh and glutamate are co-released at these synapses. The UBC brush occupies a glomerulus where granule cell dendrites are intermixed with the UBC dendrioles, both of which receive synapses from the same mossy fiber rosette and portions of the Golgi axonal plexus. In addition, the dendrioles are presynaptic to granule cell dendrites, forming dendrodendritic contacts that display features of excitatory synapses. Branches of the UBC axon in the granular layer bear large endings resembling mossy fibers. The UBCs may represent an extraordinary device for feedforward, excitatory links along the mossy fiber pathways of cerebellum and dorsal cochlear nucleus.
(fonte: NCBI - PubMed )
sono riuscito a trovare solo questo:
ok, ho prenotato la domanda
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Le cellule unipolari a spazzola sono una classe di interneuroni eccitatori presenti nello strato granulare della corteccia cerebellare (o cervelletto). Qui ricevono gli impulsi provenienti da grandi sinapsi di tipo glutammatergico.
Queste cellule sono caratterizzate da un singolo dendrite che termina con una "punta a spazzola" di dendrioli.
I dendrioli rappresentano il principale apparato sinaptico e si articolano strettamente con una singola fibra "muschiosa" formando un glomerulo caratterizzato da un contatto sinaptico straordinariamente estensivo.
Osservazioni elettrofisiologiche e tramite microscopia elettronica hanno evidenziato che l’inusuale ultrastruttura sinaptica potrebbe promuovere l’intrappolamento del neurotrasmettitore nella vescicola sinaptica.
Alcune delle cellule unipolari a spazzola ricevono il loro input dalle fibre muschiose acetiltrasferasi positive originatosi dai nuclei vestibolari suggerendo che l’acetilcolina e il glutammato sono co-rilasciate a queste sinapsi.
Di seguito alcuni link con articoli di approfondimento:
http://www.springerlink.com/content/8ej9mhqk7cw76nvc/
http://cat.inist.fr/?aModele=afficheN&cpsidt=1460015
http://www.ncbi.nlm.nih.gov/entrez/query.f...2&dopt=Abstract
http://pacs.unica.it/biblio/lezione12.pdf
http://www.unipv.it/golgi/Fisiologia/abstract/Perin.doc
http://www.jneurosci.org/cgi/content/full/26/36/9184
Edited by Tursiops - 1/4/2007, 15:16.
cellule unipolari |
