bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origin of specific synaptic types in the motoneuron neuropil of the monkey
Authors: Bodian David 
Published: January 2005

AbstractAn attempt has been made to establish, so far as possible, the specific types of synaptic bulbs on motoneurons which arise from extrinsic (descending and dorsal root) and intrinsic sources (interneurons). This has involved the laborious analysis of thousands of electron micrographs of material from normal motoneuron neuropil, and motoneuron neuropil of animals with lesions of spinal tracts, spinal roots, and motor cortex.Our studies have established that the large synaptic bulbs on dendrites, which are the only type in the spinal cord to possess pre‐synaptic synapses (serial synapses), are derived from monosynaptic dorsal root fibers (R bulbs). The presynaptic component of the serial synapse appeared to degenerate at levels below spinal cord transections (P bulbs). By means of transections of spinal cord we have found that descending fibers in the spinal cord terminate as one of at least two distinct classes of synaptic bulbs, one with spheroid synaptic vesicles (S) and one with flattened vesicles (F). There is evidence from several sources that the first type may often be excitatory in function and the second type inhibitory. Only synaptic bulbs with spheroid vesicles show definite signs of degeneration after lesions of the opposite motor cortex. The large (L) synaptic bulbs on motoneuron somata, associated with subsynaptic cisterns, are clearly not derived from the descending systems, or from posterior root fibers.
The central projections of the trigeminal, facial and anterior lateral line nerves in the carp (Cyprinus carpioL.)
Authors: Luiten P. G. M. 
Published: January 2005

AbstractThe central projections of the trigeminal, facial and anterior lateral line nerves were studied in the carp (Cyprinus carpio) by the Nauta and Fink‐Heimer silver techniques following rhizotomy.Degenerating trigeminal fibers were found projecting on the nucleus of the descending trigeminal root and on the medial funicular nucleus. The former can be subdivided in five portions lying dorsal to the various cranial motor nuclei. The afferent facial fibers could be traced into the facial, glossopharyngeal and vagal lobes, while the anterior lateral line nerve projects on rostral, medial and caudal parts of the medial nucleus and on the eminetia granularis. The anterior lateral line nerve can be divided into a dorsal and a ventral root, each following the same course. The role trigeminal and facial nerves play in proprioception of respiratory muscles is discussed.
Autoradiographic investigations of glial proliferation in the brain of adult mice. II. Cycle time and mode of proliferation of neuroglia and endothelial cells
Authors: Korr Hubert , Schultze Brigitte , Maurer Werner 
Published: January 2005

AbstractThe cycle time of the proliferating glial cells outside the subependymal layer of the lateral ventricle as well as that of endothelial cells was studied autoradiographically in the brains of adult and untreated mice. To determine the mean cycle time two independent methods were used. A mean cycle time of about 20 hours was obtained for glial and endothelial cells from the decrease of the mean grain number/nucleus as a function of time after tritiated thymidine (3H‐TdR) injection.Another group of experiments utilized the “method of labeled S phases.” With this method the passage of labeled cells through successive S phases is observed. Passing through S phase following 3H‐TdR injection the 3H‐labeled cells are double labeled by an additional 14C‐TdR injection. This method again resulted in a cycle time of 20 hours for glial and endothelial cells. From the present work and a former study (Korr et al., 11973) the following cell cycle parameters were derived: Cycle time 20 hours; S phase 9.4 hours; G2 less than three hours; (G2 + M) five hours; G1 five hours. The growth fraction of glial cells related to all glial cells is only 0.004.Furthermore, the present experiments show that in the case of glial cells 17% of the daughter cells after mitosis become pyknotic and are eliminated from the glial cell population. Apart from this cell loss, after mitosis about onefourth of the daughter cells do not enter the next S phase. These cells leave the growth fraction and are replaced by a corresponding number of non‐proliferating glial cells. There is a relatively extensive permanent exchange of cells between the growth fraction and non‐growth fraction of glial cell.
Crossed pathways from the entorhinal area to the fascia dentata. I. Normal in rabbits
Authors: Hjorth‐Simonsen A. , Zimmer J. 
Published: January 2005

AbstractThe entorhinal area projects to the Ammon's horn and the fascia dentata by way of the medial and lateral perforant paths that originate in the medial and lateral part of that area, respectively. The two tracts terminate at different laminar levels in the molecular layers of the ipsilateral hippocampal regio inferior and fascia dentata.Using the Fink‐Heimer technique, each of the perforant paths in the normal rabbit is now shown to innervate the antero‐dorsal extremes of the Ammon's horn and fascia dentata in both hemispheres. The crossed and uncrossed components of each path innervate homotopic zones on each side. This bilateral innervation contrasts with the situation in the rat where only very weak crossed components exist. Degeneration particles in the fascia dentata contralateral to a lesion of the perforant paths diminish in number along the course of the fibers as they proceed away from the midline, but are traceable for several millimeters. Crossed fibers are shown to pass from one hemisphere into the other directly through the fused molecular layers of the fasciae dentatae.The bilateral innervation in the rabbit indicates that even though the axons of the perforant paths are highly specific with respect to the class of neuron and the dendritic segments upon which they form synapses, they apparently do not possess a mechanism by which they can distinguish between the receptive fields in the two hemispheres. It is concluded that during ontogeny the perforant path fibers from both sides most likely compete for available synaptic sites in the rostral part of their terminal fields and that their relative amounts in the two hemispheres is governed by spatial and temporal factors.
Scanning electron microscopy of epiplexus macrophages (Kolmer cells) in the dog
Authors: Allen Delmas J. 
Published: January 2005

AbstractYoung dogs (6–14 weeks) were perfused with buffered aldehydes by standard techniques. The inferior medullary velum and tela choroidea were removed intact from the fourth ventricle, post‐osmicated, dehydrated, critical point dried, coated with palladium‐gold and examined in a Cambridge Stereoscan S4 scanning electron microscope. Selected samples after thorough scanning were routinely prepared for transmission electron microscopy (TEM).This study depicts numerous epiplexus (Kolmer cell) macrophages that exhibit extreme polymorphism. Because of the pleomorphic nature of these cells and their processes, classification based on external morphology is not practical. TEM shows their internal structure to be that of a macrophage. Bleb‐like structures and bulbous projections appear to emerge from certain ependymal cell surfaces which seem to be completely or partially devoid of cilia.
Human brain in tissue culture. I. Acquisition, initial processing, and establishment of brain cell cultures
Authors: Gilden Donald H. , Devlin Mary , Wroblewska Zofia , Friedman Harvey , Rorke Lucy Balian , Santoli Daniela , Koprowski Hilary 
Published: January 2005

AbstractThis paper details the in vitro techniques used to establish cells in culture from the brains of 40 patients, most of whom had chronic neurologic disease. The clinical and pathologic features of these patients are given. The success in establishing cell lines was dependent upon the origin of tissue (biopsy vs. autopsy), the site of removal from the brain, and various environmental and technical manipulations in vitro.
Human brain in tissue culture. III. PML‐SV40‐induced transformation of brain cells and establishment of permanent lines
Authors: Santoli Daniela , Wroblewska Zofia , Gilden Donald H. , Girardi Anthony , Koprowski Hilary 
Published: January 2005

AbstractCells from explants and monolayer subcultures of adult human brain obtained from biopsies or autopsies of ten multiple sclerosis (MS) cases, one case each of Jakob‐Creutzfeld (JC) and amyotrophic lateral sclerosis (ALS) and three cases with no central nervous system (CNS) involvement were transformed with PML‐SV40 virus. Transformation was effected to establish permanent lines of these particular adult brain cells so that sufficient quantities would be available for other research projects. The procedure previously used to transform human fibroblasts (Koprowski et al., '62) was successfully applied to human brain cells. The success of transformation was dependent on the growth condition of the cultures at the time of infection. Events occurring after viral infection and during the pre‐transformation and the post‐transformation phases are described.
The ascending projections of the dorsolateral funiculus of the spinal cord in the primate
Authors: Nijensohn Daniel E. , Kerr Frederick W. L. 
Published: January 2005

AbstractThe ascending projections of the dorsolateral funiculus of the spinal cord to the brain stem have been determined in five macaque monkeys. Connections to the lateral cervical nucleus and to the reticular nucleus of the cord in the C1 and C2 segments are present. In the medulla the most prominent connections are to the nuclei “Z” and “x” of Brodal and Pompeiano, to the rostral portion of n. gracilis and to the n. proprius of the restiform body. Minor projections reach the rostral part of the medial and lateral cuneate nuclei, the reticular nucleus, the n. centralis dorsalis and the periependymal gray. There were no projections to planes rostral to the medulla.In view of the connections established it is concluded that ascending systems in the DLF to the brain stem of primates are concerned with transmission of mechanoreceptor input to the cerebellum and thalamus and that nociceptive relay appears very unlikely.
Patterning of neuronal locus specificities in retinal ganglion cells after partial extirpation of the embryonic eye
Authors: Hunt R. K. , Berman Nancy 
Published: January 2005

AbstractA variety of transplantation procedures were used to analyze the determinants of locus specificity pattern in eye fragments prepared at stage 31/32. When right eye fragments were rotated through 0–360° in situ, or grafted to a stage 31/32 or stage 27/28 host, or grown in vitro 48 hours prior to reimplantation, the orientation of the retinotectal map always matched the anatomical orientation of the rounded‐up fragment, while the internal organization of the map was characteristic for the original fragment type: normal or double‐nasal in NF eye grafts, normal or double‐temporal in TF eye grafts, normal or double‐ventral in VF eye grafts. Fragments from stage 31/32 left eyes showed similar behavior, but mapped from the right orbit with one axis inverted as occurs after contralateral transplantation of whole left eyes. When one rounded‐up fragment and one normal eye (or one rounded‐up nasal fragment and one rounded‐up temporal fragment) were placed side‐by‐side in the same orbit and allowed to “superinnervate” the same tectum, both retinae mapped across the entire tectum with no unshared tectal regions. Finally, in fragments prepared from previously‐rotated (at stage 25/26) eyes, the organization and orientation of the map conformed to the new retinal axes, often in direct conflict with the anatomical polarity of the eye. The results are considered in terms of (1) the histogenesis of the retina in eye fragments; (2) the stability of the program for patterning of locus specificities, which is set down when the optic cup undergoes axial specification at stages 28–31; (3) the factors controlling selective modification of this program and their localization in eye fragments; and (4) the extent to which the range of locus specificities, deployed across the ganglion cell population of rounded‐up fragments, approximates that found in the normal unoperated eye.
The nerve ring of the nematode Caenorhabditis elegans: Sensory input and motor output
Authors: Ware Randle W. , Clark David , Crossland Kathryn , Russell Richard L. 
Published: January 2005

AbstractThe general organization and structure of the nerve ring, the main mass of central nervous system neuropil, in the small soil nematode Caenorhabditis elegans is described. The nerve ring receives sensory input from the anterior tip of the animal by means of six nerve bundles, all nerve fibers of which have centrally located cell bodies. The anterior sensory structures are classically divided into two types, papillary and amphidial, and are assumed responsible for mechano‐ and chemoreception, respectively. Papillary fibers enter directly into the nerve ring, whereas amphidial fibers enter the ventral ganglion, a posterior extension of the nerve ring, in a circuitous manner which is not discussed in detail. Of those papillary fibers which project into the nerve ring neuropil, 22 end in easily characterized sensory structures whereas 14 terminate distally near sensory organs but have no function which can be deduced on the basis of comparative morphology. After entering the ring the fibers maintain their identity and do not anastamose with one another. Cell bodies of each papillary sensory neuron have been mapped around the nerve ring. The cephalic musculature is shown to consist of 32 muscle cells which form four longitudinal submedial groups of eight muscles each. Innervation of this musculature occurs wholly within the CNS by means of processes of the muscle cells which are sent centrally. The anterior 16 cephalic muscle cells are innervated by the ring only, in well delimited regions termed muscle plates. The posterior 16 are dually innervated by means of processes sent both to the nerve ring plates and to their nearest medial longtitudinal nerve cord. The nerve ring neuropil is characterized as having fibers containing one of four morphologically distinct vesicle types. Gap junction contacts are observed within the main neuropil involving one of these fiber types and within the muscle plate regions among muscle processes, which do not contain vesicles. An evolutionarily primitive sensory‐motor synapse within the nerve ring is described from an identified sensory neuron onto an identified cephalic muscle cell process. Comparisons are made with the nervous system of Ascaris lumbricoides, the only other nematode to be extensively studied, to illustrate the conservativeness of the nemic nervous system.
Transneuronal changes of synaptic endings and nuclear chromatin in the trapezoid body following cochlear ablations in cats
Authors: Jean‐Baptiste Michel , Morest D. Kent 
Published: January 2005

AbstractThis study demonstrates long‐lasting structural changes in highly specific synaptic endings, the calyces of Held, and in the principal cells, contacted by calyces, in the medial trapezoid nucleus following acoustic deafferentation of adult cats. The normal structure of the principal cell and its afferent axosomatic endings, including the calyx and other, smaller endings, was defined in rapid Golgi impregnations and electron micrographs. Each calyciferous axon, arising from the contralateral cochlear nucleus, forms a calyx, about 35 μm in diameter, around only one principal cell body; each principal cell receives only one calyx. In electron micrographs a calycine profile typically contains a central core of neurofilaments, surrounded by mitochondria; spherical vesicles gather at multiple, asymmetric synaptic complexes. Fifteen and 30 days after unilateral labyrinthectomy the contralateral calyces showed neurofilamentous hyperplasia; mitochondria and the now enlarged synaptic vesicles decreased in number. After 30 days the contralateral principal neurons showed increased condensation of nuclear chromatin. All of these changes diminished after 56 days and were gone by seven months, when the principal cell body had shrunk by 30%. The calyx, which exhibits strongly excitatory synaptic transmission spontaneously and during acoustic stimulation, could mediate significant trophic effects. Such effects are no doubt reflected in the extensive transneuronal changes after interruption of cochlear input. These changes must involve pre‐ and post‐synaptic alterations of protein metabolism, control of which may be linked to synaptic transmission.
Some aspects of the organization of the thalamic reticular complex
Authors: Jones E. G. 
Published: January 2005

AbstractAnatomical methods which depend upon the anterograde axonal transport of isotopically labeled neuronal proteins or the retrograde axonal transport of the enzyme. Horseradis peroxidase, have been used to elucidate the relationships between the reticular complex and the dorsal thalamus and cerebral cortex. Injections of tritiated amino acide in the dorsal thalamus or cerebrasl cortex in rate, cats and monkey, show that as the bundles of thalamo‐cortical and cortico‐thalamic fibers joining a paarticular dorsal thalamic nucleus to its associated area of the cerebral cortex traverse the reticular complex, they each give rise tp dense zone of terminals occupying a sector of reticular complex which is relatively constant for that dorsal thalamic nucleus and cortical area. However, because of the wide extent of the dendritic fields of the reticular cells and the degree of overlap between the sectors of the complex subtended by adjacent dorsal thalamic nuclei and adjacent cortical areas, it is likely that the reticular complex samples thalamo‐cortical and cortico‐thalamic activity in a somewhat unspecific manner. Fibers passing to the reticular complex from the intralaminar nuclei of the thalamus appear to be associated with the projection from the intralaminar nuclei of the thalamus appear to be associatied with the projection from the intralaminar nuclei to the striatu.Injections of tritiated amino acids in the reticular complex itself and injections of horseradish peroxidase in various other parts of the brain show that the only efferent pathway from thr reticular complex terminates in the nuclei of the dorsal thalamus. The reticdular complex does not appear to send fibers to other components of the ventral thalamus nor to the cerebral cortex.
Observation on the lateral olfactory tract of the rat
Authors: Price J. L. , Sprich W. W. 
Published: January 2005

AbstractThe number and size of the axons in the lateral olfactory tract of the rat have been measured at several rostro‐caudal levels, from material prepared for electron microscopy. Immediately caudal to the olfactory peduncle, an average of 42,000 ± 3,000 axons were counted in the tract, while near the caudal limit of the tract an averge of 32,000 ± 2,800 axons were counted. The average internal cross‐sectional area of axons measured at two levels of the tract was 1.6 ± 1.3 μm2 and 1.1 ± 0.9 μ2, corresponding to averge internal diameters 1.4 ± 1.3 μm and 1.2 ± 1.1 μ, respectively. The axons in the lateral part of the tract were found to be significantly larger than those in the medial part of the tract; for one level the average cross‐sectional area of axons in the lateral part of the tract was 1.6 ± 1.0 μm2 (equivalent diameter 1.4 ± 1.1 μm) while only 0.7 ± 0.6 μm2 (equivalent diameter 0.9 ± 0.9 μm) in the medial part of the tract. The thickness of the myelin sheath of the axons is generally related to axon diameter, increasing from 0.1–0.2 μm for axons 0.4 to 0.8 μm in diameter to 0.3–0.4 μm for axons greater than 2.0 μm in diameter. The ratio of the inside diameter to the outside diameter of the fiber (ratio “g”) is between 0.7 and 0.8 for most axons in the lateral olfactory tract.The axons which leave the tract laterally and medially are substantially smaller than the axons within the tract (average cross‐sectional area 0.55 ± 0.35 μm2 on the lateral side) and probably are collaterals of the axons within the tract. Unmyelinated nerve processes, probably axons, were also found in the tract.Qualitative observations from light and electron microscopical material agree well with the quantitative data, and further suggest that mixing of axons from different parts of the olfactory bulb occurs in the rostral part of the tract. This is supported by experiments with injections of 3H‐amimo acids into localized portions of the olfactory bulb. These indicate that there is some degree of point‐to‐point organization in the most rostral part of the tract, but that this is lost in the caudal part of the olfactory peduncle.
Neuroplasticity in the rearrangement of olfactory tract fibers after neonatal transection in hamsters
Authors: Devor Marshall 
Published: January 2005

AbstractOlfactory bulb efferent axons run caudally in the lateral olfactory tract (LOT) to end in a broad cortical field in the ventral forebrain. Principles governing the plastic rearrangement of this fiber population after early lesions were probed by cutting the tract in hamster pups and studying the distribution of surviving olfactory bulb projections in adulthood using silver and autoradiographic techniques. The spatial pattern of rearrangement proved to depend on the extent of the cut and also the age at which it was made. For example, after complete LOT section at seven days of age no bulb efferents appeared distal to the cut but the proximal projection increased in laminar thickness and spread laterally and medially beyond its normal cytoarchitectonic boundaries. This spread was less pronounced in animals with earlier or later lesions. After transection of only part of the LOT fibers at seven days of age the proximal input was similarly increased. Just distal to the transection, uncut fibers sprouted collaterals to fill the terminal sites vacated as a result of the lesion. In these cases, however, the farthest distal parts of the projection field lost their normal innervation. In a tentative interpretation of these data it is proposed that developing LOT fibers tend to conserve their total amount of axonal arbor. That is, when distal branches are pruned off surgically, the axon compensates by producing extra proximal branches. When an overabundance of proximal collaterals are produced in axons that have not been surgically pruned, the growth of more distal axonal branches is stunted in compensation.
Synapses in the interpeduncular nucleus: Electron microscopy of normal and habenula lesioned rats
Authors: Lenn Nicholas J. 
Published: January 2005

AbstractFour types of synapses have been identified in the rat interpeduncular nucleus. The S synapses were formed by the main horizontal plexus of habenulointerpeduncular axons. They contained spherical synaptic vesicles and formed asymmetrical en passant contacts with dendritic processes. The crest synapses had all of these features in common with the S synapses, but occurred in pairs with the two contact zones coextensive and largely parallel on opposite sides of markedly attenuated dendritic processes. Synaptic glomeruli found in this nucleus consisted of several crest synapses engulfed by sheet‐like dendritic processes. Identical crest synapses also occurred on dendritic crests. In a limited number of cases, both S and crest synapses arose in common from single axons. Following destruction of the habenular nuclei unilaterally or bilaterally, as expected from the above observations, both S and crest synapses underwent dense degeneration. In some cases with bilateral lesions and in all cases with unilateral lesions, only one of the two axonal endings forming a crest synapse degenerated while the other remained unaffected.Axons containing flat vesicles forming symmetrical axodendritic synapses, axosomatic synapses, and subjunctional bodies associated with S or crest synapses were all minor features of this nucleus. Aspects of the unusual synaptology of this nucleus are discussed in terms of morphology, physiology and transmitter chemistry.