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  • 1
    Electronic Resource
    Electronic Resource
    Interrelations of basket cell axons and climbing fibers in the cerebellar cortex of the rat (1970)
    Springer
    Anatomy and embryology 132 (1970), S. 191-227 
    Details
    ISSN: 1432-0568
    Keywords: Cerebellar cortex ; Cytology ; Axons ; Synapses ; Purkinje cells ; Dendritic thorns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An analytical study was undertaken with both electron microscopy and the rapid Golgi method in order to clarify the interrelations of climbing fibers, basket cell axons, and Purkinje cell dendrites. The two fibers are readily distinguished in electron micrographs by means of their differing content of microtubules and neurofilaments, the packing density of synaptic vesicles, and the disposition of their synaptic junctions on the Purkinje cell dendrite. Climbing fibers are generally thin and contain many microtubules. They give off attenuated collaterals, whose rounded varicosities are densely packed with vesicles and which form en passant synapses with clusters of thorns projecting from the major Purkinje dendrites. In contrast, basket axons are relatively thick and contain many neurofilaments. By means of slight dilatations containing loosely aggregated vesicles, the axon and its collaterals form numerous synapses en passant with the smooth dendritic shafts and the perikaryon of the Purkinje cell. Climbing fibers and basket cell axons run along parallel with each other but without forming axo-axonic synapses as they ascend over the surface of the Purkinje dendrites. Both fibers form especially elaborate intertwined festoons at the branching points of the major dendrites. The kinds of synapses found are described in detail, and the functional implications are discussed. The hypothesis is developed that the dendritic thorn is a device for isolating the subsynaptic membrane from electrical events in the rest of the dendrite at the cost of reducing the effectiveness of the synapse. This principle is incorporated in the Purkinje dendrite—parallel fiber synapses, in which an individual fiber can be expected to have little importance. The disadvantage of using thorns as postsynaptic surfaces can be mitigated by clustering them and increasing the number of thorns contacted by each presynaptic terminal. This method is utilized at the junctions between the climbing fiber and the Purkinje dendrite to produce one of the most powerful excitatory synapses known. It is furthermore suggested that the elaborate plexus of climbing fibers and basket cell axons synapsing in the crotches of branching dendrites is strategically located to control the flow of information in the Purkinje cell dendritic tree.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00523377
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  • 2
    Electronic Resource
    Electronic Resource
    The synapse en marron between Golgi II neurons and mossy fibers in the rat's cerebellar cortex (1971)
    Springer
    Anatomy and embryology 133 (1971), S. 274-287 
    Details
    ISSN: 1432-0568
    Keywords: Cerebellum ; Cytology ; Synapses ; Mossy fibers ; Glomeruli ; Golgi II neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Mossy fibers engage in synapses en marron with the somata of some Golgi II cells. These synapses resemble in all particulars the synapses en marron made by climbing fibers except for the distinctive characteristics of the presynaptic terminal. The mossy fiber, with its axial stream of neurofilaments and mitochondria and its loose aggregations of round synaptic vesicles, makes an extensive contact with the wrinkled surface of the Golgi II perikaryon. Synaptic complexes are confined to the depths and sides of the furrows in the Golgi cell. The free side of the mossy fiber terminal often articulates with large numbers of granule cell dendrites, an arrangement similar to that found in ordinary glomeruli. These synaptic connections may be interpreted in the light of the physiological evidence that Golgi II cells inhibit granule cells that are not strongly activated by mossy fibers. Since each granule cell receives four to six mossy fibers, strong activation may require either a selected frequency pattern or synchrony of several inputs. The collateral inhibition indirectly evoked by the same mossy fiber via Golgi II cells would suppress those granule cells not receiving concurrent excitation from other mossy fibers or the favored pattern of excitation. In contrast, granule cells simultaneously activated by other mossy fibers would not be inhibited but would send impulses to the molecular layer. Thus, the glomerulus would behave as a filter that increases the signal-to-noise ratio of the excitatory input to the Purkinje cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00519303
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  • 3
    Electronic Resource
    Electronic Resource
    The nucleus paragigantocellularis lateralis in the rat (1981)
    Springer
    Anatomy and embryology 161 (1981), S. 355-371 
    Details
    ISSN: 1432-0568
    Keywords: Reticular Formation ; Serotonin ; Chemosensitive ; Cardiovascular ; Analgesia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The nucleus paragigantocellularis lateralis (PGCL) is located in the ventral portion of the rostral medulla. Serial sections of the rat brainstem were examined in the three cardinal planes and the boundaries of the PGCL were determined. In order to visualize the shape and extent of the nucleus, a three-dimensional reconstruction of the PGCL was made from a series of coronal sections. Measurements of neuronal areas, lengths, and widths indicate that a number of neuronal types are present. Small neurons measure less than 150 μm2 and large neurons greater than 250 μm2. Some neuronal types are distributed preferentially throught the PGCL, and on this basis the nucleus may be divided into caudal and rostral subgroups. Most large neurons (〉250 μm2) are found in the caudal portion. Certain neurons contain intranuclear rods, and these neurons are often disposed in small groups, especially common in the caudal PGCL. Two morphologically distinct neuronal types incorporate 3H-serotonin when this marker is infused into the ventricular system; the other neurons not marked by this method probably contain other, different transmitters. On the basis of neuronal measurements and staining qualities, it is ascertained that the PGCL is a parvocellular reticular nucleus characterized by many neuronal types.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00316048
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  • 4
    Electronic Resource
    Electronic Resource
    The nucleus paragigantocellularis lateralis in the rat (1981)
    Springer
    Anatomy and embryology 161 (1981), S. 373-390 
    Details
    ISSN: 1432-0568
    Keywords: Reticular formation ; Chemosensitive ; Cardiovascular ; Respiration ; Analgesia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Injections of horseradish peroxidase (HRP) were placed in the middle or caudal portion of the nucleus paragigantocellularis lateralis (PGCL) and 24 h later the entire spinal cord and brain were processed and examined for labeled neurons. Spinal afferents arise from all levels of the cord. Rexed's lamination scheme was adapted to the spinal cord of the rat and labeled neurons were localized to laminae IV, V, VII, VIII and X mainly on the side contralateral to the injection. At cervical levels, labeled neurons were consistently found bilaterally. The medial reticular nuclei of the medulla and pons contained HRP-labeled perikarya, which were concentrated most heavily in the nuclei reticularis medullae oblongatae ventralis, gigantocellularis, and pontis caudalis predominantly ipsilateral to the injection. The medial vestibular nucleus was consistently labeled. HRP-labeled perikarya were found bilaterally within the commissural portion and in the medial part of the nucleus of the solitary tract on the side of the injection. The rostral portion of the PGCL receives afferents from some secondary auditory nuclei: the ipsilateral inferior colliculus and the posterior ventral cochlear nucleus bilaterally. Thus, the rostral PGCL may be involved in auditory feedback loops. The caudal raphe nuclei are a major source of afferents to the caudal PGCL. The lateral hypothalamic area, para ventricular nucleus, and zona incerta also contain labeled neurons when injections are centered in the caudal portion of the nucleus. Because of its connections, the PGCL may be divided into two subnuclei which roughly correlate with two cytoarchitecturally distinct regions (Andrezik et al. 1981). The rostral PGCL is involved in auditory reflexes. The entire PGCL but especially its caudal portion modulates autonomic reflexes which regulate the cardiovascular system and respiration. Analgesia resulting from electrical stimulation and injections of morphine or enkephalins probably are mediated by the caudal portion of the nucleus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00316049
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  • 5
    Electronic Resource
    Electronic Resource
    Hyperinnervation of arrested granule cells produced by the transplantation of monoamine-containing neurons into the fourth ventricle of rat (1980)
    Springer
    Anatomy and embryology 159 (1980), S. 1-15 
    Details
    ISSN: 1432-0568
    Keywords: Transplant ; Monoamine neurons ; Cerebellar development ; Serotonin ; Norepinephrine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An attempt to learn whether chemically specific neurons affect the sequence of cerebellar development was made by transplanting ectopic tissues rich in monoamines adjacent to the early developing cerebellum of neonatal rat. Three types of brainstem grafts were used: (1) ventral midline raphe region, (2) inferior olivary region, (3) locus coeruleus region. When transplanted into the fourth ventricle of host animals, neurons from the transplant sprout axons into the host cerebellar parenchyma producing changes in cerebellar cytoarchitecture. The changes produced by the three types of brain grafts were investigated with conventional light and electron microscopy. Autoradiography with tritiated serotonin (3H-5HT) and norepinephrine (3H-NE) and immunocytochemistry using antibodies raised against serotonin allowed identification of the chemical specificity of the process. The three fundamental changes caused by the transplants were folial malformation, arrest of migration of external granule cells, and disruption of the Purkinje cell monolayer. By intraventricular infusion of 3H-5HT and immunocytochemistry with antibodies raised against serotonin, an extraordinarily rich serotonin innervation was detected within or around the foci of arrested granule cells after transplantation with raphe-rich tissue. In addition to an increase in the number of parallel fibers that accumulate 3H-5HT, numerous glomerulus-like structures were observed within the foci. After transplantation with locus coeruleus fragments, intraventricular infusion of 3H-NE demonstrated some increase of labeled fibers inside the foci of arrested granule cells, but the extent of the increase of NE fibers was less marked than the increase in 5-HT fibers. Conventional electron microscopic study revealed numerous synaptic formations within the arrested granule cell foci. Terminals containing large granular vesicles were seen, which resemble serotonin nerve terminals previously described (Chan-Palay, 1975, 1977). Thus ectopic neuronal tissues rich in monoamine neurons survive after transplantation into the fourth ventricle of neonatal rats, can disrupt cerebellar development, and sprout axons that hyperinnervate foci of neurons in disarray, in a pattern reminiscent of the normal innervation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00299251
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  • 6
    Electronic Resource
    Electronic Resource
    Autoradiographic experiments to examine uptake, anterograde and retrograde transport of tritiated serotonin in the mammalian brain (1980)
    Springer
    Anatomy and embryology 159 (1980), S. 137-149 
    Details
    ISSN: 1432-0568
    Keywords: Raphe serotonin cells ; Inferior olivary cells ; Cerebellum, afferent ; 3H-5HT ; Retrograde and anterograde transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In an attempt to define the potential application of neurotransmitter-specific transport as a method of tracing fiber connections, we have examined the uptake and subsequent ortho- and retrograde transport of tritiumlabeled serotonin (3H-5HT) in the cerebellum-raphe pallidus system. Injection of various concentrations of 3H-5HT followed by different post-injection survival times revealed different labeling patterns in the injected sites and different patterns of transport. The most striking feature is that nonserotonin neurons as well as serotonin cells were able to take up and transport the tritium label in both ortho- and retrograde fashion. The non-sertonin-specific nature of this uptake and transport is more obvious at higher concentrations of 3H-5HT (more than 9x10-5 M), with longer survival times and following pretreatment with monoamine oxidase inhibitors. At a concentration of 9x10-6 M 3H-5HT, only specific uptake seems to take place as evidenced by label in known serotonin cells and fiber systems; however, it was impossible to detect by autoradiography any ortho- or retrograde transport at this low concentration. Non-specific uptake and transport were observed following injection into the vestibular nuclei and oculomotor complex. This suggests that non-specific uptake and the transport of 3H-5HT or metabolites may also occur in other regions of the central nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304974
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  • 7
    Electronic Resource
    Electronic Resource
    Tendril and glomerular collaterals of climbing fibers in the granular layer of the rat's cerebellar cortex (1971)
    Springer
    Anatomy and embryology 133 (1971), S. 247-273 
    Details
    ISSN: 1432-0568
    Keywords: Cerebellar cortex ; Cytology ; Climbing fibers ; Collaterals ; Glomeruli ; Synapses ; Granular layer ; Purkinje cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Rapid Golgi preparations show that two kinds of collaterals issue from the climbing fiber in its course through the granular layer. The first resembles the tendrils found in the molecular layer and consists of globose varcosities connected by a very fine thread. In electron micrographs these varicosities in the granular layer contain dense aggregates of round synaptic vesicles at least 520 Å in diameter and the connecting threads contain numerous microtubules. The varicosities synapse on the somata of Golgi II cells and on the shafts of dendrites belonging to both Golgi II and granule cells. The second type of collateral emerges from the main stem of the climbing fiber as a stout branch that sprays out abruptly into a large efflorescence. In electron micrographs this terminal appears as the central stellate structure in a glomerulus and is packed with round synaptic vesicles like those in the tendril varicosities. Granule cell dendrites encircle the terminal and occasionally synapse with it. Often the terminal in the glomerulus also forms an extensive junction—a synapse en marron—with the some of Golgi II cell. In this region the surface of the cell is wrinkled like a Spanish chestnut and the glomerular terminal is reciprocally ridged and furrowed to match. Synaptic complexes occur only in the furrows of the cell surface. A broad subsynaptic zone is filled with a fine filamentous matrix. This study provides the first morphological identification and description of climbing fiber terminations in the granular layer, the existence of which has been suggested by earlier Golgi studies and postulated by neurophysiologists. The fact that climbing fibers synapse on both granule cells and Golgi II cells complicates the analysis of the way in which the cerebellar cortex operates, because these two cells have postsynaptic effects of opposite sign. The climbing fiber is known to evoke a complex discharge from the Purkinje cell, consisting of a large primary spike and smaller secondary potentials. It is suggested that when a climbing fiber volley traverses the granular layer, the granule cells on which it synapses are induced to excite stellate and basket cells in the molecular layer which in their turn inhibit the secondary spikes of the climbing fiber response in the Purkinje cell. Meanwhile the Golgi II cells, stimulated by the same climbing fiber volley, suppress the granule cells and thus transsynaptically limit the duration of the inhibitory effects exerted by the interneurons in the molecular layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00519302
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  • 8
    Electronic Resource
    Electronic Resource
    High voltage electron microscopy of rapid Golgi preparations. Neurons and their processes in the cerebellar cortex of monkey and rat (1972)
    Springer
    Anatomy and embryology 137 (1972), S. 125-152 
    Details
    ISSN: 1432-0568
    Keywords: Axons ; Dendrites ; Synapses ; Neuroglia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The rapid Golgi reaction produces initially a red and secondarily a black precipitate in certain neurons, neuroglia, and endothelial cells of nerve tissue. High voltage electron microscopy shows that the red impregnation is a dense, intracellular, fibrillar meshwork of rodlets with a filamentous substructure. The black impregnation is due to the superimposition of very dense globular and polyhedral crystals that stud the surface of the underlying red fibrillar network. When present in quantity, these globules conglomerate to form a crust over the impregnated structure. This can cause distortion in the shape of the structure and considerable overestimation of its size in light microscope studies of black Golgi material. As seen in the high voltage electron microscope, the varicosities in the course of red-impregnated axons (for example, parallel fibers in the cerebellar cortex) show light circular patches that correspond to synaptic sites. Some varicosities have more than one site, an observation that is corroborated by conventional electron microscopy. The study of Golgi preparations in the high voltage electron microscope would enable one to make an accurate estimate of the number of synapses effected by an axon along its course. This information cannot otherwise be obtained, either by light microscopy or by electron microscopy of thin sections. Stereoscopic pairs show the three-dimensional interrelationships between neurons and neuroglia in the neuropil. Selected area electron diffraction studies on sections of Golgi material can provide in situ chemical information on the impregnated fibers. Thus, high voltage electron microscopy may provide an important auxiliary technique to complement light microscopy and standard electron microscopy in the study of the structure and organization of nervous tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00538787
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  • 9
    Electronic Resource
    Electronic Resource
    Acetylcholinesterase activity in certain glomeruli and Golgi cells of the granular layer of the rat cerebellar cortex (1972)
    Springer
    Anatomy and embryology 137 (1972), S. 317-334 
    Details
    ISSN: 1432-0568
    Keywords: Histochemistry ; Nervous system ; Climbing fibers ; Mossy fibers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The Karnovsky method for the precise demonstration of acetyl and butyryl cholinesterase was applied to perfusion-fixed rat cerebellar vermis, and the results were examined by light and electron microscopy. Heavier concentrations of acetylcholinesterase activity were demonstrated in lobules IX and X than elsewhere in the cerebellar cortex. Acetylcholinesterase was found in the intercellular clefts and in relation to the synaptic membranes of mossy fiber and climbing fiber terminals in the granular layer of the uvula and nodulus. Within these lobules there were also similar endings of both the mossy and climbing fibers that showed no reaction. Acetylcholinesterase activity was found in the nuclear envelope and the cisternae of the rough endoplasmic reticulum of most Golgi cell perikarya and on the surface membranes of their axon terminals. Reasons for the selective distribution of acetylcholinesterase are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00519100
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  • 10
    Electronic Resource
    Electronic Resource
    Gamma-aminobutyric acid pathways in the cerebellum studied by retrograde and anterograde transport of glutamic acid decarboxylase antibody after in vivo injections (1979)
    Springer
    Anatomy and embryology 157 (1979), S. 1-14 
    Details
    ISSN: 1432-0568
    Keywords: Purkinje cell ; Dentate nucleus ; Cerebellar cortex ; GAD ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Injections of characterized antibody against glutamic acid decarboxylase (GAD), the enzyme responsible for the synthesis of γ-aminobutyric acid (GABA), were made into the cerebellum. Small cortical injections of anti-GAD antibody produced labeled stellate, basket, Purkinje, and Golgi cells and their processes at the injection site. Anterograde transport of GAD antigen-antibody complexes in Purkinje cell axons caused intense labeling of terminals in deep cerebellar and several vestibular nuclei. Small groups of mossy fiber rosettes labeled and produced retrograde labeling and GAD immunoreactivity in a small number of pleomorphic neurons in the deep cerebellar nuclei. Injections into the dentate nucleus produced retrograde labeling in Purkinje cell bodies and anterograde label in a small number of mossy fiber rosettes. All projections conformed to previously reported topographic distributions of corticonuclear and nucleocortical cerebellar pathways. These findings confirm the GABA content of most Purkinje cell-deep nuclei connections and provide new evidence for a GABA component in part of the nucleocortical pathway in the cerebellum. Immunocytochemical controls for specificity were conducted by injections of preimmune rabbit serum as a substitute for GAD antibody. Only nonspecific labeling was obtained in these cases. Colchicine caused a cumulative enhancement of GAD immunoreactivity in all cases. The present studies indicate that the method of in vivo antibody injections can be utilized to study chemically specific connections in nervous tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315638
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