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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The interrelationships of corticotropin-releasing factor (CRF) immunoreactive neuronal cell bodies and processes have been examined in the paraventricular nucleus (PVN) of adrenalectomized-dexamethasone treated rats. Antisera generated against ovine CRF (oCRF) were used in the peroxidase-anti-peroxidase-complex (PAP)-immunocytochemical method at both the light and electron microscopic levels. In this experimental model, a great number of CRF-immunoreactive neurons were detected in the parvocellular subdivisions of the PVN and a few scattered labelled parvocellular neurons were also observed within the magnocellular subunits. Characteristic features of immunolabeled perikarya included hypertrophied rough endoplasmic reticulum with dilated endoplasmic cisternae, well developed Golgi complexes and increased numbers of neurosecretory granules. These features are interpreted to indicate accelerated hormone synthesis as a result of adrenalectomy. Afferent fibers communicated with dendrites and somata of CRF-immunoreactive neurons via both symmetrical and asymmetrical synapses. Some neurons exhibited somatic appendages and these structures were also observed to receive synaptic terminals. Within both the PVN and its adjacent neuropil, CRF-immunoreactive axons demonstrated varicosites which contained accumulations of densecore vesicles. CRF-containing axons were observed to branch into axon collaterals. These axons or axon collaterals established axo-somatic synapses on CRF-producing neurons in the parvocellular regions of the PVN, while in the magnocellular area of the nucleus they were found in juxtaposition with unlabeled magnocellular neuronal cell bodies or in synaptic contact with their dendrites. The presence of CRF-immunoreactive material in presynaptic structures suggests that the neurohormone may participate in mechanisms of synaptic transfer. These ultrastructural data indicate that the function of the paraventricular CRF-synthesizing neurons is adrenal steroid hormone dependent. They also provide morphological evidence for the existence of a neuronal ultrashort feed-back mechanism within the PVN for the regulation of CRF production and possibly that of other peptide hormones contained within this complex.
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PMID:Evidence for local corticotropin releasing factor (CRF)-immunoreactive neuronal circuits in the paraventricular nucleus of the rat hypothalamus. An electron microscopic immunohistochemical analysis. 390 7

Oxytocin-containing neurons and axon terminals contacting the neurons of the rat paraventricular nucleus were investigated by the peroxidase-antiperoxidase technique for light and electron microscopy. At the light microscopic level the reaction product was seen to fill the somata, dendrites and axons of the neurons. At the ultrastructural level the immunoprecipitate was localized on cytoplasm (including ergastoplasm) and neurosecretory granules (NSG) of the somata; microtubules, ergastoplasm and NSG of the dendrites; and NSG of the axons. Axon terminals synapsing on the surface of the labelled somata and dendrites were exclusively unlabelled. The somata and dendrites were observed to receive both asymmetrical (Gray's type I) and symmetrical (Gray's type II) synapses with clear, mostly spherical and flattened vesicles, respectively. Frequently, pleomorphic vesicles and a few densecore vesicles occurred in both types of synapses. There also were present some unlabelled bridge-like axon terminals making 'double' synapses either on two labelled dendritic processes or on one unlabelled and one labelled dendrite. The present findings demonstrate that the somata and dendrites of the oxytocin-containing neurons receive diverse innervation. At the same time there was no evidence in this study for synaptic input to the labelled axons of the neurons.
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PMID:A light and electron microscopic study of oxytocin-containing neurons in the paraventricular nucleus of the rat. 391 66

The solitary nucleus is the first level of the central nervous system where processing of taste information can occur. A structural basis for that processing was investigated. Facial taste afferent axons were labelled by application of horseradish peroxidase to either the chorda tympani or the geniculate ganglion. The labelled afferent fibers in the rostral solitary nucleus were studied with light and electron microscopy. Preterminal facial taste afferent axons enter the nucleus from the solitary tract with a pronounced lateral to medial trajectory. The axons bear numerous preterminal and terminal swellings that, with the electron microscope, were identified as synaptic endings located in glomeruli. The endings are ovoid or scalloped, indented by structures that surround them. The primary afferent endings contain large, round vesicles and synapse, by means of slightly asymmetrical junctional complexes, on small dendrites and spines. Two types of unlabelled endings, surrounding the labelled ones, contact the dendrites receiving taste afferent input or contact the endings of taste afferent axons themselves. One type is variable in size and contains scattered large round vesicles. It resembles a presynaptic dendrite. The other is a small axonal ending packed with small, pleomorphic vesicles, that engages in symmetrical junctions. The synaptic milieu of the taste endings allows for the possibility of modulation of taste-elicited activity in afferent endings or second-order neurons by other, possibly interneuronal, inputs.
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PMID:Anatomy of the gustatory system in the hamster: synaptology of facial afferent terminals in the solitary nucleus. 395 91

Neurons in the ventrolateral (VL) subdivision of rat trigeminal nucleus oralis (Vo) have most of their dendritic arbors confined within this region. This study examines the morphology and synaptic connections of a population of myelinated primary trigeminal axons that arborize within VL and are in a position to provide input directly to VL neurons. Primary axons were visualized for light and electron microscopic analysis by injecting 30% horseradish peroxidase (HRP) in 2% dimethylsulfoxide (DMSO) into the sensory root of the trigeminal nerve and allowing 24-36 hours for the anterograde transport of HRP into the terminal axonal arbors. This population is characterized by its cone-shaped terminal arbors, which generate many axonal endings (2-8 micron in diameter) along unmyelinated terminal strands. These arbors arise from collaterals emanating from thinly myelinated (2-5 micron in diameter) parent branches descending in the spinal V tract, which, on the basis of their size, are considered to be small myelinated (A sigma) primary trigeminal axons. HRP-labeled P endings belonging to this population of primary axons are scalloped, filled with spherical to ovoid (40-70 nm in diameter) synaptic vesicles, and lie centrally in glomeruli where they make asymmetrical axodendritic synapses on dendritic shafts and spine heads. It is at these synapses that this population of primary trigeminal axons is probably transferring its input directly to the dendritic arbors of VL neurons. The dendritic shafts and spine heads also receive symmetrical to intermediate axodendritic synapses from endings containing flattened (70 X 29 nm) synaptic vesicles. These terminals also establish axo-axonic synapses on the P ending. Other synaptic components found less often in the glomeruli include small terminals containing oval (14-23 nm) synaptic vesicles that establish symmetrical to intermediate synapses on the P ending, boutons containing pleomorphic (35-80 nm) synaptic vesicles that form symmetrical to intermediate synapses on the P ending as well as on dendritic shafts, and small peripheral endings containing round (20-40 nm) synaptic vesicles that establish asymmetrical synapses on dendritic shafts.
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PMID:Morphology and synaptic connections of myelinated primary axons in the ventrolateral region of rat trigeminal nucleus oralis. 395 93

The rostral thalamo-hyperstriatal projection in young chicks was examined following large injections of wheat germ agglutin labelled with horseradish peroxidase (HRP-WGA) into the hyperstriatum. Retrograde labelling of thalamic neurons was present in the dorsolateral thalamus, rostrolateral part (DLAlr) and dorsolateral thalamus, lateral part (DLL). There was no evidence of a contralateral projection from the lateral anterior thalamic nucleus (LA) to the posterior aspect of the visual hyperstriatum as reported recently by Boxer and Stanford (1985). Furthermore, a comparison of labelled neurons in the contralateral rostral thalamus following injections into either the left or right hyperstriatum revealed no difference in the number of neurons. The study could therefore not confirm the presence of an asymmetrical LA-hyperstriatal projection, as reported by the above authors.
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PMID:A note on the projection from the rostral thalamus to the visual hyperstriatum of the chicken (Gallus gallus). 395 34

Neurons of the dorsal motor nucleus of the vagus nerve were studied following injections of horseradish peroxidase into the vagus nerve in a monkey (Macaca fascicularis). In frozen sections, the dorsal motor nucleus appeared to be completely filled by labeled medium-sized (20-30 micron in long axis) neurons. Labeled dendrites from these neurons often extended outside the borders of the nucleus into the nucleus of the tractus solitarius. In 1 micron thick plastic sections and ultrathin sections of the dorsal motor nucleus, two distinct types of neurons were observed with the light and electron microscope. Medium-sized neurons with abundant cytoplasm and an oval nucleus were retrogradely labeled with HRP, while small (10-15 micron in long axis) neurons with a paucity of organelles and an invaginated nucleus remained unlabeled. Medium-sized neurons outnumbered the small neurons by approximately five to one. The synaptic organization of the dorsal motor nucleus in monkey was studied and compared with that in cat. The porportions of different types of axosomatic synapses were similar in both species. Terminals containing round vesicles and making symmetrical or asymmetrical contact with the postsynaptic structure were more common than synaptic terminals containing pleomorphic vesicles. In both species, there was a slightly greater synaptic density on the medium-sized neurons than on the small neurons. The synaptic density in the monkey dorsal nucleus was greatest on the smallest dendrites in the neuropil and least on the somata.
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PMID:Ultrastructure of the dorsal motor nucleus of the vagus nerve in monkey with a comparison of synaptology in monkey and cat. 396 33

In a light and electron microscopic study of the substantia nigra of the rat, the distribution and morphology of nigrotectal neurons and the pattern of termination of striatonigral fibres have been examined following the placement of horseradish peroxidase injections in the superior colliculus and kainic acid lesions in the dorsal striatum. In confirmation of previous findings, nigrotectal neurons which had been identified by the retrograde transport of horseradish peroxidase from the superior colliculus had mainly medium sized somata, varied from fusiform to stellate in shape and were found in mainly ventral regions of the rostral two-thirds of the substantia nigra pars reticulata. On electron microscopic examination, single and multiple (from two to six) degenerating striatonigral boutons were found in synaptic contact with the soma, proximal mainstem dendrites and small dendrites (but mainly on small dendrites) of labelled nigrotectal and unlabelled nigral neurons in the ventral region of the pars reticulata. In addition, a small number of degenerating striatonigral boutons formed axoaxonic synapses with degenerating or normal boutons which were presynaptic to nigral dendrites. Almost all of the identified striatonigral synapses were of the symmetrical type, although a few degenerating boutons established asymmetrical synaptic contacts on unlabelled dendrites. These findings provide evidence of a monosynaptic input from the dorsal striatum to nigrotectal projection neurons in the substantia nigra and thus demonstrate the existence of a bineuronal pathway from the striatum through the substantia nigra to the superior colliculus. The possible significance of the pattern of termination of striatonigral fibres in the substantia nigra is discussed with reference to the known dendritic arborization of nigral neurons.
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PMID:The striatonigral projection and nigrotectal neurons in the rat. A correlated light and electron microscopic study demonstrating a monosynaptic striatal input to identified nigrotectal neurons using a combined degeneration and horseradish peroxidase procedure. 400 Apr 78

The organization of projections from the principal sensory trigeminal nucleus (PSN) to the hypoglossal nucleus (XII) in the rat was investigated at the light and electron microscopic level with retrograde and anterograde axonal tracer techniques. Microiontophoretic injection of horseradish peroxidase (HRP) into XII resulted in retrograde labeling of neurons confined to the dorsal one-third of the PSN. Labeled neurons were found bilaterally, although a clear preponderance for ipsilateral distribution was evident. Most labeled neurons were found in the medial one-third and caudal two-thirds of the PSN. Labeled neurons were large (30-50 micron), round-to-pear shaped multipolar cells with dendrites oriented primarily in the mediolateral direction. At the electron microscopic level, HRP reaction product was found throughout the cytoplasm of soma and processes of PSN projection neurons. The ultrastructural characteristics of these cells included a round, centrally placed nucleus and invaginated nuclear envelope, sparse Nissl bodies, numerous free ribosomes, mitochondria, lysosomes and Golgi complexes. Three to four main stem dendrites gradually tapered from the cell body and numerous synaptic terminals impinged upon soma and dendrites of labeled PSN neurons. Microiontophoretic injection of tritiated amino acids or HRP into the dorsal one-third of the PSN resulted in moderately dense terminal labeling in XII bilaterally, although mainly ipsilaterally. Terminal labeling was found diffusely throughout all regions of XII. Fibers descended the brainstem in the dorsolateral reticular formation and entered XII ventrolaterally. At the electron microscopic level, boutons containing HRP reaction product were found to synapse on dendritic processes in XII. Labeled boutons were characterized by clear, spherical vesicles and an asymmetrical postsynaptic density. The significance of these results are discussed in relation to oro-lingual motor behavior.
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PMID:Organization of projections from the principal sensory trigeminal nucleus to the hypoglossal nucleus in the rat: an experimental light and electron microscopic study with axonal tracer techniques. 401 94

Cholinergic neurons in the basal forebrain which project to the frontal cortex were studied by combining the retrograde transport of a conjugate of horseradish peroxidase and wheat germ agglutinin with choline acetyltransferase immunohistochemistry. Neurons that were both retrogradely labelled and immunoreactive were found on the medial, lateral, and ventral borders of the globus pallidus, within the globus pallidus, as well as in the substantia innominata and ventral pallidum region. The cell bodies averaged 31 by 19 micron in size and had sparsely branching dendrites. Cells which were labelled by both techniques were first characterised in the light microscope and then studied in the electron microscope. The perikarya had large amounts of cytoplasm with abundant organelles. The nuclei were indented, were usually eccentrically placed, and contained prominent nucleoli. The synaptic input onto the cell bodies and their dendrites was studied in serial sections. The synaptic input onto the perikarya and proximal dendrites was sparse but the density increased on more distal regions of the dendrites. Subjunctional bodies were associated with the postsynaptic membrane in 20-30% of the synaptic contacts and these were classified as asymmetrical; the remaining contacts could not be classified because of an association of the immunoreaction product with the postsynaptic membrane. The synaptic input to these cells was distinctly different from that onto typical globus pallidus cells, the perikarya and dendrites of which were characteristically ensheathed in synaptic boutons.
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PMID:A correlated light and electron microscopic study of identified cholinergic basal forebrain neurons that project to the cortex in the rat. 404 33

We used wheatgerm agglutinin conjugated to horseradish peroxidase (WGA:HRP) as an anterograde tracer to label the terminals of the lemniscal, spinothalamic, and trigeminothalamic pathways in the ventrobasal complex of the rat thalamus (VB). The use of benzidine dihydrochloride (BDHC) as the chromogen allowed us to view the labeled profiles with the electron microscope and permitted us to compare the morphology of the terminals from the various pathways. We found that all the labeled somatosensory pathways terminate in the VB in the form of large terminals that contain round synaptic vesicles and make numerous asymmetrical synaptic contacts, usually with dendritic protrusions and proximal dendrites. The present results demonstrate that pathways conveying noxious and non-noxious somatosensory information terminate upon thalamic neurons with synaptic terminals having similar morphological features.
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PMID:Ultrastructural analysis of the terminals of various somatosensory pathways in the ventrobasal complex of the rat thalamus: an electron-microscopic study using wheatgerm agglutinin conjugated to horseradish peroxidase as an axonal tracer. 407 Aug 93


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