bluuebunny/crossref_metadata_2025_split huggingface dataset:
The projections of the entopeduncular nucleus and globus pallidus in rat as demonstrated by autoradiography and horseradish peroxidase histochemistry
Authors: Carter D. A. , Fibiger H. C. 
Published: January 2005

AbstractThe efferent projections of the globus pallidus (GP) and entopeduncular nucleus (EP) in the rat were studied using autoradiographic and horseradish peroxidase (HRP) histochemical techniques. Following stereotaxic injections of 3H‐leucine into EP, transported label was observed in the lateral part of the ventromedial nucleus (VM) of the thalamus, and more laterally, in the ventrolateral aspect of the ventral lateral‐ventral anterior thalamic complex (VALv). Selective accumulation of autoradiographic grains was also found in the parafascicular nucleus (Pf) and in the lateral habenular nucleus. HRP injections into the thalamus confirmed the entopeduncular projections to these nuclei. Comparison of grain distribution in the thalamus after 3H‐leucine injections into EP and the zona reticulata of the substantia nigra (Clavier et al., '76) indicates that there is considerable overlap between nigral and EP projections to both VM and Pf. The nigrothalamic and entopedunculothalamic projections to VM and VALv are discussed with reference to the possibility that in the rat these nuclei are homologous to specific nuclei within the ventral lateral‐ventral anterior complex in primates.Injections of 3H‐leucine into GP resulted in major accumulations of autoradiographic grains in the medial part of the subthalamic nucleus and the substantia nigra. Light and diffuse labelling was also observed in the dorsal thalamus. However, a consistent feature of the GP injections was that they appeared to result in diffusion of isotope to the reticular nucleus of the thalamus, and in view of the widespread thalamic projections of this nucleus, the label in dorsal thalamus could not be positively attributed to pallidal efferents. HRP injections throughout the thalamus failed to produce reactive cells in the GP. These experiments provided no firm support therefore for a recent suggestion that there are extensive projections from the globus pallidus to the thalamus in rat.
Early stages of uptake and transport of horseradish‐peroxidase by cortical structures, and its use for the study of local neurons and their processes
Authors: Vanegas Horacio , Holländer Horstmar , Distel Hansjürgen 
Published: January 2005

AbstractIt is well known that, when horseradish‐peroxidase (HRP) is injected into the central nervous system, it is taken up by nerve terminals and retrogradely transported to their cells of origin. We have now injected HRP into the visual cortex of cats in order to study light‐microscopically the pattern of its spread, the neural structures that take it up locally, and the initial steps of its retrograde descent towards the dorsal lateral geniculate nucleus (LGNd). Special attention was given to post‐injection times of ten minutes to eight hours, but animals with up tofive days' survival were also analyzed.It was found that the brown spot produced by the initial spread (primary diffusion) of HRP remains constant in size for about two hours and then spreads out (secondary diffusion) to involve neighboring visual cortical areas. Secondary diffusion, however, does not result in further retrograde labelling of LGNd neurons. Local nervous structures labelled during primary diffusion of HRP include a large number of infracortical axons, many of which show bifurcations directed towards the cortex. As HRP descends within these axons, fewer and deeper axonal branchings appear labelled, as though, after initial uptake, HRP were no longer taken up. The possible reasons for the lack of further HRP uptake, including observed local inflammatory reactions, are discussed. Intracortical labelled structures include neuron somata and processes. These resemble Golgi‐impregnated structures and, particularly at short survival times, show fine details such as dendritic spine necks, terminal bouton stalks, synaptic contacts, and a remarkable degree of axonal preterminal and terminal branching. Some of these structures were also examined electron‐microscopically.
Connections of the visual cortex in the hedgehog (Paraechinus hypomelas). I. Halamocorticalprojections
Authors: Gould Harry J. , Hall William C. , Ebner Ford F. 
Published: January 2005

AbstractVisual thalamocortical projections were studied in the Pakistani hedgehog with anterograde degeneration techniques following large aspiration lesions and discrete electrolytic lesions of visual thalamic nuclei. After 3‐ to 9‐day survival periods, the brains were processed and stained with the Fink‐Heimer technique, and examined with the light microscope.The resutls of these studies show that there are at least four separate thalamic nuclei that project to visual cortex in the hedgehog. First, the dorsal lateral geniculate nucleus projects with a topographic order to layer IV and the adjacent portion of layer III of striate cortex. Second, a thalamic transition zone, adjacent to the dorsal lateral geniculate nucleus, projects widely to layer VI throughout striate cortex and possibly to all laminae of striate cortex in the area lying just medial to the striate‐parastriate border. The laminar pattern of termination of this transition zone is similar to that of the lateral posterior nucleus. Third, the lateral posterior nucleus projecs with little discernible topographic localization to layer VI of both striate and parastriate cortex, and in addition, to the remaining laminae of parastriate cortex except the outer one‐half of layer I. Fourth, the anterior intralaminar region projects to the outer one‐third to one‐half of layer I in both striate and parastriate cortex. Evidence derived from ablations of the entire thalamus on one side suggests that there may be still another thalamic nucleus that projects to visual cortex in the hedgehog.
Catecholamine innervation of the basal forebrain. I. The septal area
Authors: Moore Robert Y. 
Published: January 2005

AbstractThe septal area of the rat is known to receive a rich innervation by axons of catecholamine (CA) neurons. In the present study this innervatic was studied using biochemical assay of CA content and fluorescence histochemical analysis of the distribution of CA‐producing axons to determine the nuclei origin of the septal CA innervation and the effects of lesions on these parameters. The autoradiographic tracing technique and the horseradish peroxidase (HRP)‐retrograde transport technique also were used for this purpose.The norepinephrine (NE) content of the normal septal area is 1,162 ± 127 ng/g and the dopamine (DA) content is 522 ± 106 ng/g. Hemisection of the brainstem caudal to the locus coeruleus results in a 47% decrease in septal NE content and a unilateral locus coeruleus lesion produces a 48% decrease in septal NE content. These observations suggest that the NE innervation of the septal area arises approximately equally from the locus coeruleus and nuclei in the caudal brain stem. This is confirmed, at least in part, by the anterograde and retrograde transport studies. The DA innervation of the septal area is shown by all of the techniques employed to arise almost exclusively from cells of the ventral tegmental area.NE axons arising from the locus coeruleus distribute in the septal area to the hippocampal rudiment, the nucleus of the diagonal band, the interstitial nucleus of the stria terminalis, the medial septal nucleus, the lateral septal nucleus and the nucleus septofimbrialis. In each area the innervation is sparse to moderate in density and has the plexiform organization typical of locus coeruleus innervation. The brainstem NE innervation is very dense in the interstitial nucleus of the stria terminalis, moderately dense in the lateral septal nucleus and sparse in the nucleus of the diagonal band.The DA axons innervating the septum terminate in two distinct patterns. The first is identical to that seen in the neostriatum. Preterminal axons are very fine and non‐varicose. As they reach a terminal area they branch markedly and give rise to extremely numerous, closely‐packed, fine varicosities. This type of DA innervation is found in the medial part of the lateral septal nucleus in a dense band and about some scattered lateral septal nucleus neurons, in the nucleus accumbens and in the interstitial nucleus of the stria terminalis. The second pattern is for non‐varicose preterminal axons to branch and terminate in pericellular baskets about lateral septal nucleus neurons or simply terminate in the lateral septal nucleus neuropil. In each case the terminal branches give off distinct varicosities which are larger than those formed in the first pattern of DA innervation.Thus, the septal area has a complex organization of CA innervation with NE axons arising from caudal brainstem nuclei and the locus coeruleus and DA axons arising from the ventral tegmental area.
Neurons associated with the dorsal longitudinal flight muscles ofDrosophila melanogaster
Authors: Coggshall John C. 
Published: January 2005

AbstractThe anatomy of the neurons associated with the six fibers formingthe dorsal longitudinal flight muscle (DLM) of Drosophila melanogaster has been investigated using a horseradish peroxidase label. The two dorsal‐most fibers are innervated by the same neuron whose cell body is in the dorsal, contralateral, mesothoracic region of the thoracic ganglion. The ventral‐most fourfibers are innervated by four neurons whose cell bodies are clusteredin the ventral, ipsilateral, prothoracic region. The processes ofallfive of these cells ramify extensively in the dorsal part of theipsilateral and contralateral mesothoracic neuromeres.A large interneuron has been discovered which is associated with the DLM and whose cell body is located contralaterally.Several neurons with small cell bodies on the ventral midline of the mesothoracic neuromere are also consistently labeled. A single fiber projects dorsally from a midline cell body, forms a Y‐branch near the top of the ganglion and apparently sends an axon into each posterior dorsal mesothoracic nerve (PDMN) subsequently innervating the DLM.
Organization of the mossy fiber system of the rat studied in extended hippocampi. II. Experimental analysis of fiber distribution with silver impregnation methods
Authors: Gaarskjaer Frank B. 
Published: January 2005

AbstractThe mossy fibers, a major intrinsic hippocampal pathway connecting the dentate granule cells with the pyramidal cells in CA4 and CA3, have been reexamined in rats using mainly Fink‐Heimer silver impregnation methods for demonstration of degenerating axons. By extending isolated hippocampi and cutting sections normal to the long axis, simple two‐dimensional reconstructions of both the lesions and the resultant degeneration could be made.In the hilus, the zone with the greatest concentration of degenerating boutons was found between the lesioned granule cells and the CA3 pyramidal cells abutting on the hilus; outside this zone the concentration declines rather rapidly. Degenerating boutons were also observed in low concentration up to 200‐300 μm septal and temporal to the lesion.The mossy fibers in CA3 nearest the hilus have an intrapyramidal course and display a lamellar organization with fibers from the granule cells of the medial blade lying deep to those from the dentate crest. These in turn lie deep to those from the granule cells of the lateral blade.A mediolateral difference in the projection of the granule cells on the CA3 pyramidal cells was discovered: fibers from the medial granule cells descend about 600 μm in the temporal direction, whereas fibers from the lateral granule cells descend about 1,200 μm. This causes a divergence of the fibers from one single level, especially of the part of the fibers, being farthest away from the hilus. The degree of descent of the fibers from each mediolateral position of the granule cells was constant at all septotemporal levels examined.
Superior colliculus connections with the extraocular motor nuclei in the cat
Authors: Edwards Stephen B. , Henkel Craig K. 
Published: January 2005

AbstractDirect and indirect projections from the cat superior colliculus to the extraocular motor nuclei were studied using the orthograde autoradiographic tracing method, the retrograde horseradish peroxidase technique, and Golgi methods.The results show that the superior colliculus projects to the central gray matter directly overlying the oculomotor complex. This projection arises almost entirely from the rostral third of the colliculus, and it terminates most heavily over the rostral half of the oculomotor complex. Dendrites of oculomotor cells extend into this tectal termination zone, making direct tecto‐oculomotor contacts possible. Central gray cells within this termination zone project bilaterally to the abducens nuclei. It is proposed that the superior colliculus projection to the supraoculomotor central gray matter and the projection from the central gray matter to the abducens nuclei play a role in convergent eye movements.The superior colliculus projects lightly to a cell group directly ventrolateral to the trochlear nucleus.The superior colliculus sends a small direct projection to the contralateral abducenns nucleus and a substantial projection to wide regions of the reticular formation that have been shown previously to project, in turn, to the abducens nucleus. Colliculus cells projecting to the abducens nucleus and adjacent reticular formation are located only in the caudal three‐fourths of the colliculus, where they become increasingly concentrated at successively more caudal levels. It is proposed that the graded density of the cells of origin of this projection is the basic structural mechanism by the which the colliculus generates horizontal foveating saccades of different amplitudes.Laminar analysis of the origin of all the superior colliculus projections to the extraocular motor regions described here revealed that they arise mostly from the stratum griseum intermedium.
The forms of non‐pyramidal neurons in the visual cortex of the rat
Authors: Feldman Martin L. , Peters Alan 
Published: January 2005

AbstractRapid Golgi preparations from area 17 of young adult rats have been studied to determine the morphology and distribution of non‐pyramidal neurons. Such cells were observed in all of the cellular laminae of the cortex, but were particularly prevalent in layers IV and V. Non‐pyramidal neurons were categorized according to two features: (1) dendritic projection pattern, and (2) abundance of dendritic spines. Dendritic patterns were classified as multipolar, bitufted, and bipolar, and spine patterns as spinous, sparsely spinous, and spine‐free. Spinous dendrites were associated only with multipolar neurons, while sparsely spinous and spine‐free dendrites were each associated with cells of all three non‐pyramidal dendritic patterns. The most frequently observed non‐pyramidal cell types were multipolar cells of the spine‐free and sparsely spinous varieties. All of the general cell types encountered have been described in the literature on non‐pyramidal neurons, indicating the lack of any unique forms in rat area 17. An analysis of the dendritic projections of individual non‐pyramidal neurons through particular cortical laminae made possible an evaluation of common sources of dendrites present in the neuropil of each layer. Non‐pyramidal cell axons were impregnated only in small numbers. Spinous multipolar axons invariably exhibited a descending main branch, while the axons of bipolar neurons were distributed in a narrow vertical field. Axonal patterns of remaining cell types, including Golgi type II arborizations, did not appear to correlate consistently with dendritic morphology. Axons of the basket cell type and “horsetail” axons associated with double bouquet cells of Cajal's original type were not impregnated.
The role of ependyma in regeneration of the spinal cord in the urodele amphibian tail
Authors: Nordlander Ruth H. , Singer Marcus 
Published: January 2005

AbstractThe new spinal cord formed during tail regeneration in te newt first develops as a caudal extension of the ependymal tube. Neuroblasts and neuroglia subsequently differentiate from cells of the ependymal tube in a proximal‐caudal sweep. Descending axons from the cord rostral to the lesion and from newly differentiating neurons travel in channels which are present prior to the ingrowth of axons. The present study confirms previous observations from our laboratory and presents details of the ultrastructural relations of axons and ependymal processes within the cord.The ependymal cell surface facing channels typically forms numerous digitor sheet‐like protuberances which extend into the channel lumen. As axons enter the channels in increasing numbers these protuberances partially subdivide the axons into smaller groupings, even occasionally segregating individual axons.At levels where fibers have not yet entered or have most recently entered the ependymal channels two specializations appear on the ependymal plasmalemma facing the channels and their axons: coated membranes and hemides‐mosome‐like structures. At more mature levels, where many fibers have already; entered the channels, axons in contact with ependymal processes sometimes show synapse‐like vesicle accumulations with associated membrane densities. Coated membranes and hemidesmosome‐like structures are lacking at these levels.Our observations suggest that ependymal processes, in addition to providing substrate and direction for regenerating spinal cord axons, may also furnish or exchange more specific information at the morphologically identifiable specializations described above.
Serotonin neurons of the midbrain raphe: Ascending projections
Authors: Moore Robert Y. , Halaris Angelos E. , Jones Barbara E. 
Published: January 2005

AbstractThe ascending projections of serotonin neurons of the midbrain raphe were analyzed in the rat using the autoradiographic tracing method. Axons of raphe serotonin neurons ascend in the ventral tegmental area and enter the medial forebrain bundle. A number of fibers leave the major group to ascend along the fasciculus retroflexus. Some fibers enter the habenula but the majority turn rostrally in the internal medullary lamina of the thalamus to innervate dorsal thalamus. Two additional large projections leave the medial forebrain bundle in the hypothalamus; the ansa peduncularis‐ventral amygdaloid bundle system turns laterally through the internal capsule into the striatal complex, amygdala and the external capsule to reach lateral and posterior cortex, and another system of fibers turns medially to innervate medial hypothalamus and median eminence and form a contralateral projection via the supraoptic commissures. Rostrally the major group in the medial forebrain bundle divides into several components: fibers entering the stria medullaris to terminate in thalamus; fibers entering the stria terminalis to terminate in the amygdala; fibers traversing the fornix to the hippocampus; fibers running through septum to enter the cingulum and terminate in dorsal and medial cortex and in hippocampus; fibers entering the external capsule to innervate rostral and lateral cortex; and fibers continuing forward in the medial olfactory stria to terminate in the anterior olfactory nucleus and olfactory bulb.
Ascending connections to the forebrain in the tegu lizard
Authors: Lohman A. H. M. , van Woerden‐Verkley I. 
Published: January 2005

AbstractThe ascending connections to the striatum and the cortex of the Tegu lizard, Tupinambis Nigropunctatus, were studied by means of anterograde fiber degeneration and retrograde axonal transport. The striatum receives projections by way of the dorsal peduncle of the lateral forebrain bundle from four dorsal thalamic nuclei: nucleus rotundus, nucleus reuniens, the posterior part of the dorsal lateral geniculate nucleus and nucleus dorsomedialis. The former three nuclei project to circumscribed areas of the dorsal striatum, whereas nucleus dorsomedialis has a distribution to the whole dorsal striatum. Other sources of origin to the striatum are the mesencephalic reticular formation, substantia nigra and nucleus cerebelli lateralis. With the exception of the latter afferentation all these projections are ipsilateral.The ascending connections to the pallium originate for the major part from nucleus dorsolateralis anterior of the dorsal thalamus. The fibers course in both the medial forebrain bundle and the dorsal peduncle of the lateral forebrain bundle and terminate ipsilaterally in the middle of the molecular layer of the small‐celled part of the mediodorsal cortex and bilaterally above the intermediate region of the dorsal cortex. The latter area is reached also by fibers from the septal area. The large‐celled part of the mediodorsal cortex receives projections from nucleus raphes superior and the corpus mammillare.
The central projections of the glossopharyngeal and vagus ganglia in the mallard, Anas platyrhynchos L.
Authors: Dubbeldam Jacob L. , Brus Ernst R. , Menken Steph B. J. , Zeilstra Schelte 
Published: January 2005

AbstractThe central projections of the glossopharyngeal and vagus nerves in the mallard have been studied with the Fink‐Heimer I method and are compared to those of the trigeminal and facial nerves. The N. vagus projects ipsilaterally and contralaterally upon the central nuclei of the solitary complex, except the most rostral part of it, upon the n. sulcalis dorsalis, the parasolitary nuclei and the n. commissuralis. The glossopharyngeal nerve contributes to the rostral pole of the n. centralis anterior and to the n. ventrolateralis anterior of the solitary complex, but it has also terminal fields in a cellgroup sIX of the principal sensory trigeminal nucleus, in a small cellgroup sIXd on the dorsum of the descending trigeminal tract, in the n. interpolaris of this tract and in nuclei of the cuneate complex. There is hardly any overlap of the respective terminal fields. The convergence of projections from N VII and N IX can be connected with the presence of tastebuds in upper and lower bill and in the soft palate. The converging projections from N V and N IX in “trigeminal” nuclei may reflect the functional coherence of the mechanoreceptors in bill and tongue. It is suggested that these nuclei play a role in the feeding behavior.
Variability of laminar patterns in the human lateral geniculate nucleus
Authors: Hickey T. L. , Guillery R. W. 
Published: January 2005

AbstractThe structure of the human lateral geniculate nucleus has been studied on serial Nissl stained sections from 57 human brains. Most of the brains were from neurologically normal individuals and were obtained during routine autopsy procedures. The laminar arrangement within the human nucleus is surprisingly variable. It is always possible to recognize a small segment with two layers (the monocular segment), one with four layers and one with six layers. Often an 8‐layered segment can also be seen. The posterior half of the nucleus, within which central vision is represented, is made up mainly of six layers, and is the least variable part of the nucleus. Here the layers lie roughly parallel to each other. In the anterior half of the nucleus the laminar arrangement is more variable, and the layers often form complex and irregular interdigitations with each other. The 8‐layered segment varies greatly in size and may be absent. It generally lies at the edge of the 4‐layered segment not, as might have been expected, within the borders of the 6‐layered segment.In many parts of the nucleus nerve cells are organized in short rows that run perpendicular to the layers; also, individual nerve cells are elongated in this direction. This neuronal orientation follows the lines of projection that are defined by the borders of a zone of retrograde degeneration, and also corresponds to the orientation of a cellular discontinuity that probably is the geniculate representation of the blind spot. Thus, we conclude that the neuronal orientation indicates the lines of projection within the nucleus.