bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology of parallel fibres in the cerebellar cortex of the rat: An experimental light and electron microscopic study with biocytin
Authors: Pichitpornchai C. , Rawson J. A. , Rees S. 
Published: January 2005

AbstractMicroinjections of biocytin have been made in the granular layer of the rat cerebellar cortex in order to label the axonal projections of a localised population of granule cells. Light microscopic techniques were used to determine the lengths of the parallel fibres and to measure the spacing and size of the fibre varicosities. Fibres were longest in the superficial one‐third of the molecular layer, where mean overall length was 4.7 mm, and mean length decreased to 4.2 mm in the lower one‐third of the molecular layer. We found no very short fibres but a small population deep in the molecular layer had a branch length of about one‐half the average. Mean intervaricosity interval and varicosity size varied with distance from proximal to distal along the fibres. Mean intervaricosity interval was 3.7 μm within 250 μm of the fibre bifurcation points and progressively increased towards the distal ends, where the mean interval was 7.4 μm. Mean varicosity size was 0.82 μm2 in this proximal region and decreased to 0.47 μm2 about 1.2 mm distally. Mean intervaricosity interval on the ascending axons of the granule cells was 4.0 μm. Electron microscopy revealed that a high proportion (89%) of the parallel fibre varicosities formed synaptic junctions. The majority of the synapses (91%) were formed on Purkinje cell dendritic spines. Some varicosities also formed simultaneous synaptic contacts or double synapses with two spines. These double synapses occurred more frequently in the proximal region of the fibres (11%) than on the distal ends (2%). The length of the postsynaptic density also differed according to the location of the varicosities and the mean length at the proximal parallel fibre synapses was 0.59 μm compared with 0.38 μm at the distal synapses. It is concluded that a beam or bundle of parallel fibres originating from cells in a focal region of the granular layer will exert a graded synaptic influence on its target Purkinje cells, with the most powerful influence occurring on cells located around the proximal region of the fibres where they bifurcate and the weakest action being exerted on cells located at the distal end of the fibres. © 1994 Wiley‐Liss, Inc.
Dorsal nucleus of the lateral lemniscus in the rat: Concentric organization and tonotopic projection to the inferior colliculus
Authors: Merchán Miguel A. , Saldaña Enrique , Plaza Ignacio 
Published: January 2005

AbstractA basic principle of organization in auditory centers is the topographic‐tonotopic order. Whether this applies to the dorsal nucleus of the lateral lemniscus (DNLL), however, is still debated. To clarify this problem, we have utilized the neuroanatomical tracers horseradish peroxidase (HRP) and biotinylated dextran (BD) injected into different regions of the central nucleus of the inferior colliculus (CNIC) in the rat.After large injections of HRP that included most of the CNIC, retrogradely labelled neurons were found all across the ipsi‐ and contralateral DNLL, showing that all parts of this nucleus innervate the CNIC bilaterally. More neurons were seen consistently on the side contralateral to the injection site. Labelled fibers, however, were abundant ipsilaterally, but scarce in the contralateral DNLL.Single, small injections of HRP or BDinto the CNIC resulted in labelling in restricted areas of the ipsi‐ and contralateral DNLL. In coronal sections, the neurons and fibers labelled in the ipsilateral DNLL formed a well‐defined, ring‐shaped structure made of dendrites and axons oriented parallel to each other, which we termed “annular band.” The observation of serial sections revealed that the annular band seen in any individual section represents a slice through a more or less complete three‐dimensional, hollow, ovoid structure oriented rostrocau‐dally. The position and diameter of the annular band changed as the injection site was shifted along the tonotopic axis of the CNIC. Single injections placed in the ventromedial, high‐frequency region of the CNIC produced a large annular band along the periphery of the DNLL. After injections placed in progressively more dorsolateral, lower‐frequency regions of the CNIC, the annular band became smaller in diameter and occupied a successively more central position in the DNLL. Double injections along the tonotopic axis of the CNIC resulted in two roughly concentric annular bands. The labelled neurons and fibers in the contralateral DNLL systematically occupied a position symmetric to the annular band seen ipsilaterally.These findings indicate that the rat DNLL is primarily composed of neurons with flattened dendritic arbors and flattened fields of terminal fibers. These two elements intermingle, forming concentric layers around the geometric center of the nucleus. The axons of neurons within corresponding layers on the two sides converge onto the CNIC of both sides in a strict topographic fashion: the peripheral layers project to the ventromedial, high‐frequency region of the CNIC, and the central layers project to the dorsolateral, low‐frequency region. These results suggest that the concentric arrangement of the DNLL is the substrate of its tonotopic organization. © 1994 Wiley‐Liss, Inc.
Immunocytochemical localization of immunoglobulins in the rat brain: Relationship to the blood‐brain barrier
Authors: Aihara Naoto , Tanno Hirokazu , Hall J. J. , Pitts Lawrence H. , Noble L. J. 
Published: January 2005

AbstractThe central nervous system has been traditionally regarded as an immunologically privileged area. This feature has been in part attributed to the blood‐brain barrier, which provides a restrictive interface to circulating immunoglobulins (IgG). Recent kinetic studies suggest that the barrier to immune proteins is not absolute, but rather may be regulated by a specific transfer mechanism. In this study, we confirm the presence of IgG in the central nervous system by immunocytochemistry and demonstrate a close anatomical relationship between the distribution of this protein and the blood‐brain barrier.IgG was immunolocalized in the normal rat brain by using monoclonal and polyclonal antibodies to IgG and its subclasses. On the basis of an initial evaluation, the most appropriate antibodies and dilutions were selected for subsequent analyses. In the first study, IgG and albumin were immunolocalized in adjacent sections. In the second study, horseradish peroxidase (HRP) was given intravenously prior to sacrifice, in order to examine artifacts related to perfusion fixation. The distribution of HRP and IgG was then examined in adjacent sections. In the third study, IgG was immunolocalized in sections of brain after mild traumatic head injury.A monoclonal antibody to IgG2a and a polyclonal antibody to IgG were selected on the basis of specificity and consistent, mutual localization. Distinct, patchy, perivascular staining, infrequently associated with labeled neurons, was noted throughout the brain. Electron microsocopy confirmed the perivascular localization; IgG was localized along the basal lamina of microvasculature and within the adjacent parenchyma. Albumin and HRP did not exhibit a similar pattern of perivascular immunostaining. After head injury, prominent immunostaining for IgG was observed in the injured hemisphere.In summary, these data indicate that the normal rat brain contains IgG, which dramatically increases after head injury. The distinct perivascular distribution in the normal brain suggests local microvascular permeability. This permeability is selective for IgG, since albumin does not share a similar perivascular localization. The neuronal staining which is closely associated with perivascular label may reflect one intracellular route for extravasated IgG. © 1994 Wiley‐Liss, Inc.
Ultrastuctural studies of the primate lateral geniculate nucleus: Morphology and spatial relationships of axon terminals arising from the retina, visual cortex (area 17), superior colliculus, parabigminal nucleus, and pretectum of Galago crassicaudatus
Authors: Feig Sherry , Harting John K. 
Published: January 2005

AbstractThe electron microscopic autoradiographic tracing method has been used to examine the morphology and postsynaptic relationships of five projections (retina, cortical area 17, superior colliculus (tectal), parabigeminal nucleus, and pretectum) to the dorsal lateral geniculate nucleus of the greater bush baby galago crassicaudatus.Retinal terminals have been examined in the contralaterally innervated layer of each of the three matched pairs [parvi‐(X‐cell), magno‐ (Y‐‐cell), and koniocellular (small, W‐cell)] of geniculate layers. These terminals are large and contain pale mitochondria and round vesicles (RLPs). RLPs are presynaptic to juxtasomatic regions of parvi‐and magnocellular neurons. In contrast, RLPs innervate more distal regions of konicellular neurons.Labeled cortical, tectal, and parabigeminal terminals are relatively small and contain round vesicles na dark mitochondria. Cortical terminals in each of the three representative layers are presynaptic to small diameter dendrites. No convergence of cortical and retinal terminals has been seen in any layer. Labeled tectal and parabigminal terminals are found primarily in the koniocellular layers, but the latter are also seen in all other layers. Tectal and parabigeminal terminals have been observed converging with retinal terminals on dendrites of some koniocellular neurons.Labeled pretectogeniculate terminals contain densely packed pleomorphic vesicles, dark mitochondria, and a dark cytoplasmic matric. These terminals, which are present in each of the representative layers, are presynaptic to conventional dendrites and profiles containing loosely despersed pleomorphic vesicles and a pale cytoplasmic matrix. © 1994 Wiley‐Liss, Inc.
The vocal control pathways in budgerigars differ from those in songbirds
Authors: Striedter Georg F. 
Published: January 2005

AbstractPrevious studies concluded that parrots and oscine songbirds, two taxa that have independently evolved the ability to learn vocalizations, possess similar neural circuits for vocal control. These investigations suggested, however, that the vocal control systems of parrots and songbirds may also differ in several respects. Most importantly, auditory inputs to the vocal control system derive from Field L in songbirds, but this area does not appear to project to the vocal control system in parrots. The principal aims in the present study were, therefore, to determine (1) exactly how similar the vocal control system in budgerigars is to that in songbirds and (2) whether the vocal control system in budgerigars receives auditory inputes from areas other than Field L.Biotinylated and fluorescently labeled dextrans were injected into five telencephalic nuclei of the vocal control system in budgerigars and into the physiologically identified auditory portions of the frontal neostriatum and nucleus basalis. The results indicate that the forebrain voca; control system in budgerigars is only superficially similar to that in songbirds. Many of the vocal control nuclei differ between the two taxa in both cytoarchitecture and connections. The nuclei in budgerigars that are comparable to those of the accessory loop of the vocal control system in songbirds, for example, do not form an accessory loop in budgerigars. The vocal control systems in the two taxa differ most significantly in the source of their auditory inputs. In songbirds, auditory information is conveyed to the vocal control system via Field L, whereas, in budgerigars, the auditory inputs to the vocal control system derive from nucleus basalis and the frontal neostratum. A phylogenetic analysis suggests that the midbrain and medullary vocal control pathways are homologous across all birds, but that most of the vocal control circuits in the forebrain have probably evolved independently in parrots and songbirds. © 1994 Wiley‐Liss, Inc.
Taste bud expression of human blood group antigens
Authors: Smith David V. , Klevitsky Raisa , Akeson Richard A. , Shipley Michael T. 
Published: January 2005

AbstractSome human blood group antigens are expressed by rodent epithelial cells at different stages of differentiation. Since adult taste cells are continually replaced throughout life, we investigated the expression of the H, B, A and Lewisb blood group determinants by cells of the rat fungiform, foliate and vallate papilae. We employed antibodies against the trisaccharide structures of the H, B, and A blood group antigens and against the Lewisb blood group epitope in studies of normal and denervated taste buds. The antibody against the H antigen reacted with the majority of cells in all taste buds and with cells in the spinous layer of the tongue epithelium. The B antigen was expressed by the majority of taste cells but not by other epithelial cells. The expression of the A antigen was significantly less in the fungiform taste buds than in the vallate or foliate taste buds. The A antigen was also abundantly expressed in the acini of the lingual salivary glands. The Lewis b epitope was expressed by a subset of cells in taste buds of the fungiform, foliate and vallate papillae. Taste buds are trophically dependent upon gustatory nerve innervation. Transection of the chorda tympani or the IXth nerve resulted in the loss of expression of these molecules from the gustatory epithelium, indicating that they are expressed only on differentiated taste cell. The blood group antigens are lactoseries carbohydrates; they are differentially expressed in developing cochlear hair cells and olfactory neurons and may play roles in cell‐cell recognition, adhesion, and other interactions important in the developing nervous system. They could have similar functions in the taste and olfactory systems, where the receptors are continually renewed and new synapses between the receptors and their neural targets continually form. © 1994 Wiley‐Liss, Inc.
Triceps surae motoneuron morphology in the rat: A quantitative light microscopic study
Authors: Chen Xiang Yang , Wolpaw Johathan R. 
Published: January 2005

AbstractThe rat is now the model of choice for many studies of motor function. However, little quantitative information on the structure of rat motoneurons is available. In conjunction with efforts to define the physiologic and anatomic substates of operantly conditioned plasticity in the spinal cord, 13 physiologically identified triceps surae motoneurons in the rat lumbar spinal cord were labeled intracellularly with horseradish peroxidase and completely reconstructed and measured with a computer‐based neuron‐tracing system.Somata were all located in the ventral horn of lumbar segments 4–5, had and average diameter of 35 μm, and had 6–12 dendrites. Dendrites remified throughout the ventral horn and also penetrated the white matter. Their spread was greater in the rostocaudal and dorsoventral directions (1.53 ± 0.24 mm and 1.35 ±0.23 mm, respectively) than in the mediolateral direction (0.85 ± 0.14 mm). Regardless of soma location, dendritic fields usually extended throughout the ipsilateral coronal cross‐section of the ventral horn.As a result, the ventral or lateral extent of the field was correlated strongly with the soma's distance from the ventral or lateral border, respectively, of the ventral horn. Furthermore, although soma locations in the coronal plane varied widely, the centers of the dendritic fields tended to cluster near the center of the ventral horn. Dendrites constituted 96.2–98.4% (mean ± SD = 97.3 ± 0.7%) of the total neuronal surface area. Each of the 104 dendrites studies had an average of 13 branch points and 27 segments. First‐order segment diameters ranged from 1.4 to 11.7 μm (mean ±SD = 5.3 ± 2.1 μm). Total dendritic length, surface area, volume, number of dendritic segments, and maximum segment order were correlated strongly with diameter of the first‐order segment. Proceeding distally between branch points, the mean decrease in dendritic diameter (i. e., tapering) ± the standard deviation was 22 ± 8% of the proximal diameter. The average ratio ± the standard deviation of the sum of the average diameters of each daughter segment raised to the 1.5 power to the average diameter of the parent segment raised to the 1.5 power (i. e., Rall's ratio; Rall, 1959) was 0.87 ± 0.08.In comparison with cat α‐motoneurons, rat motoneurons had smaller soma diameters, fewer dendrites, smaller total surface areas, and shorter total dendritic lengths. However, the number of terminations per dendrite was similar in the two species, so that rat motoneurons had more terminations per unit dendritic length. This greater branching density indicates that the dendritic fields of rat motoneurons are more compact and their branching structures are more densely packed that those of cat motoneurons. © 1994 Wiley‐Liss, Inc.
The return of phosphorylated and nonphosphorylated epitopes of neurofilament proteins to the regenerating optic nerve of Xenopus laevis
Authors: Zhao Yangu , Szaro Ben G. 
Published: January 2005

AbstractNeurofilament proteins of mammalian axotomized peripheral axons, which regenerate effectively, resemble those of embryonic axons. However, injured centrally projecting mammalian axons, which fail to regenerate, have very different neurofilament compositions than during development. If changes in neurofilament composition after injury reflect the ability of axotomized neurons to regenerate effectively, then the neurofilaments of centrally projecting axons that can regenerate should more closely resemble those of developing axons. In this study, the neurofilament compositions of injured optic axons of the frog, Xenopus laevis, were examined, since these axons can regenerate a fully functional projection. Antibodies to phosphorylated and nonphosphorylated forms of neurofilament proteins that had been used previously to study the neurofilament composition of newly developing X. laevisoptic axons were used in immunocytochemical studies to examine the return of neurofilaments to the optic nerve after an intraorbital nerve crush. Intraocularly injected wheat germ agglutinin conjugated to horseradish peroxidase was used to label the regenerating axons independently of their neurofilaments. Neurofilament immunoreactivities disappeared rapidly from crushed axons during the first week after surgery. By nine days after surgery, antibodies to nonphosphorylated form of middle (NF‐M) and low molecular weight (NF‐) neurofilament proteins and the Xenopusneuronal intermediate filament protein (XNIF) began to stain the nerve just beyond the lesion. By this time, however, growing axonal terminals had reached the optic chiasm. Antibodies to phosphorylated epitopes of NF‐M began to stain axons at 15 days, just as growing axons began to arrive at the optic tectum. Nonphosphorylated high molecular weight neurofilament protein (NF‐H) began to appear in axons between 18 and 21 days after surgery. Thus, the reappearance of neurofilaments during optic axon regeneration resembled the general pattern seen during development. The chief difference between development and regeneration was that neurofilament epitopes took longer to emerge during regeneration. One possibility is that cues encountered along the optic pathway influence the neurofilament composition of retinal ganglion cell axons. Then, the greater distance travelled by regenerating axons could account for the longer time taken for their neurofilament compositions to mature. © 1994 Wiley‐Liss, Inc.
Development changes in the distribution of gamma‐aminobutyric acid‐immunoreactive neurons in the embryonic chick lumbosacral spinal cord
Authors: Antal Miklós , Berki Ágnes C. , Horváth László , O'Donovan Michael J. 
Published: January 2005

AbstractThe development of γ‐aminobutyric acid (GABA)‐immunoreactive neurons was investigated in the embryonic and posthatch chick lumbosacral spinal cord by using pre‐ and postembedding immunostaining with an anti‐GABA antiserum. The first GABA‐immunoreactive cells were detected in the ventral one‐half of the spinal cord dorsal to the lateral motor exception of the lateral motor column, appeared throughout the entire extent of the ventral one‐half of the spinal gray matter by E6. Thereafter, GABA‐immunoreactive neurons extended from ventral to dorsal regions. Stained perikarya first appeared at E8 and then progressively accumulated in the dorsal horn, while immunoreactive neurons gradually declined in the ventral horn. The general pattern of GABA immunoreactivity characteristic of mature animals had been achieved by E12 and was only slightly altered afterwards. In the dorsal horn, most of the stained neurons were observed in laminae I–III, both at the upper (LS 1–3) and at the lower (LS 5–7) segments of the lumbosacral spinal cord. In the ventral horn, the upper and lower lumbosacral segments showed marked differences in the distribution of stained perikarya. GABAergic neurons were scattered in a relatively large region dorsomedial to the lateral motor column at the level of the upper lumbosacral segments, whereas they were confined to the dorsalmost region of lamina VII at the lower segments.The early expression of GABA immunoreactivity may indicate a trophic and synaptogenetic role for GABA in early phases of spinal cord development. The localization of GABAergic neurons in the ventral horn and their distribution along the rostrocaudal axis of the lumbosacral spinal cord coincide well with previous physiological findings, suggesting that some of these GABAergic neurons may be involved in neural circuits underlying alternating rhythmic motor activity of the embryonic chick spinal cord. © 1994 Wiley‐Liss, Inc.
Highly selective effects of nerve growth factor, brain‐derived neurotrophic factor, and neurotrophin‐3 on intact and injured basal forebrain magnocellular neurons
Authors: Koliatsos Vassilis E. , Price Donald L. , Gouras Gunnar K. , Cayouette Michelle H. , Burton Louis E. , Winslow John W. 
Published: January 2005

AbstractCholinergic neurons of the basal nucleus complex (BNC) respond to nerve growth factor (NCF), the first member of a polypeptide gene family that also includes brain‐derived neurotrophic factor (BDNF), neurotrophin‐3 (NT‐3), and neurotrophin‐4/5 (NT‐4/5), NGF, BDNF, and NT‐3 are enriched in hippocampus. In addition, NGF and, more recently, BDNF have been shown to stimulate the cholinergic differentiation and enhance the survival of BNC cells in vitro. The present investigation was designed to test, in a comparative fashion, the in vivo effects of human recombinant NGF, BDNF, and NT‐3 with confirmed activities in vitro on cholinergic and γ‐aminobutyric acid (GABA)‐ergic BNC neurons. The specific questions asked were whether and, to what extent, biologically active recombinant neurotrophins stimulate the transmitter phenotypes of intact cholinergic and GABAergic neurons of the BNC, and whether, and to what extent, recombinant neurotrophins protect the transmitter phenotypes of axotomized cholinergic and GABAergic neurons of the BNC following complete transections of the fimbria‐fornix (measured by ChAT mRNA hybridization). Our results confirm the profound stimulatory and p75NGFRexpression in both intact and axotomized cholinergic neurons and to exert minor effects on some cholinergic markers (e.g., ChAT immunoreactivity). NT‐3 had no influence on GABAergic neurons. Taken together, these results indicate that, despite their significant sequence homologies and their shared abundance in target fields of BNC neurons, NGF, BDNF, and NT‐3 show striking differences in their efficacies as cholinergic trophic factors. GABAergic neurons of the BNC are resistant to neurotrophins. The result of the present investigation establish that NGF excels among neurotrophins as a trophic factor for intact and injured basal forebrain cholinergic neurons. © 1994 Wiley‐Liss, Inc.