bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid changes in ultrastructure during deafferentation‐induced dendritic atrophy
Authors: Deitch Jeffrey S. , Rubel Edwin W 
Published: January 2005

AbstractThis study describes qualitative and quantitative changes in dendritic ultrastructure during the rapid atrophy of nucleus laminaris (NL) dendrites following deafferentation. The dendrites of n. laminaris neurons in the chick auditory system are segregated into dorsal and ventral dendritic tufts, which receive spatially separated innervation from the ipsilateral and contralateral nucleus magnocellularis, respectively. We have previously shown that removing the input to the ventral side of NL results in the rapid atrophy of the ventral dendrites, whereas the nondeafferented dorsal dendrites of the same cells do not change in length.The ultrastructure of NL was examined in normal animals and after deafferentation. Changes in dendritic ultrastructure were not qualitatively apparent 4 hours after deafferentation. Between 12 and 48 hours the cytoplasm of the ventral dendrites became progressively more lucent, and a gap formed in the transition between the soma and ventral dendritic cytoplasm. Many of the dendrite tips, however, appeared normal even 2 days after deafferentation. Degeneration of dendrite plasma membrane was not visible until 2 days after deafferentation. On the other hand, quantitative measurements revealed a 30% decrease in microtubule density in the initial portion of the ventral dendrite by 4 hours, and a 50–60% decrease from 12 to 48 hours after deafferentation. Neurofilament density in the initial ventral dendrites decreased 50% by 12 hours, and 70% by 2 days after deafferentation. Many of the terminals of the severed afferents remained attached to the atrophying dendrite until 2 days after surgery, when they were in advanced stages of degeneration. Glia apparently were not involved in dendrite loss.The implications of these results on the role of cytoskeleton in the production and maintenance of dendritic shape are discussed.
Neurogenesis of glutamic acid decarboxylase immunoreactive cells in the hippocampus of the mouse. II: Area dentata
Authors: Soriano Eduardo , Cobas Alberto , Fairén Alfonso 
Published: January 2005

AbstractThe temporal patterns of neurogenesis of cells showing glutamic acid decarboxylase (GAD) immunoreactivity were determined in the area dentata of the mouse. Pregnant C57Bl mice received pulse injections of (3H)thymidine from E11 through E17 (E0 being the day of mating). The distribution of (3H)thymidine‐labeled, GAD‐positive neurons in the hilus and in the different strata of the fascia dentata (stratum infragranulosum, stratum granulosum, stratum moleculare) were recorded in adult animals. A radial gradient of neurogenesis of GAD‐positive cells in the area dentata was not apparent. In the transverse axis, neurogenesis of GAD‐positive cells seemed to follow a faint suprapyramidal to infrapyramidal gradient, which was due to differential timing of neurogenesis of GAD‐positive cells destined for the stratum infragranulosum of the suprapyramidal and infrapyramidal blades of the fascia dentata. GABAergic neurons in the fascia dentata comprise a limited number of welldefined cell types. All of the differet morphologic types of GAD‐positive neurons present in the area dentata were generated prenatally. These diverse forms did not have specific times of neurogenesis. These results support the concept that the adult morphology of GAD‐positive cells in the area dentata of the mouse do not bear any relationship to their times of origin.
Diagonal band projection towards the hypothalamic supraoptic nucleus: Light and electron microscopic observations in the rat
Authors: Jhamandas J. H. , Raby W. , Rogers J. , Buijs R. M. , Renaud L. P. 
Published: January 2005

AbstractSupraoptic nucleus (SON) neurons receive a prominent gamma‐aminobutyric acid (GABA) input. This study evaluated the hypothesis, partly on the basis of recent electrophysiological data, that this innervation might arise from GABAergic neurons located in the ventral diagonal band of Broca area. For retrograde transport studies, pentobarbital‐anesthetized male Long‐Evans rats received 0.03–0.20‐μl injections of a suspension of rhodamine tagged latex microspheres into the SON. In two cases where such injections were confined to the SON, less than 60 retrogradely labeled neurons were detected in the ipsilateral diagonal band. In three animals where injections extended into the perinuclear zone around the SON, more than 2,000 retrogradely labeled cells were counted in the ipsilateral diagonal band. For anterograde transport studies, another group of animals received either 30% horseradish peroxidase (HRP) in 0.5% poly‐L‐ornithine (0.05–0.10 μl injections) or Phaseolus vulgarus (iontophoresed from a 2% solution) into the diagonal band. After survivals of 18–24 hours (HRP) or 5 days (PHAL‐L) labeled axon terminals invested the perinuclear zone above the SON. The presence of just a single fiber within the nucleus indicated a minor projection to the SON itself. The HRP‐injected material was processed for ultrastructural examination and revealed dense HRP‐labeled axon terminals in this perinuclear zone, most often (98%) forming axodendritic appositions. A postembedding colloidal gold technique to visualize GABA‐synthesizing terminals revealed that fewer than 5% of these perinuclear HRP‐labeled terminals also exhibited GABA‐like immunoreactivity. Within the SON, where GABAergic axon terminals are abundant, few (≤5%) GABAergic terminals contained HRP. Therefore, only a minor component of this prominent GABAergic innervation of SON neurons appears to arise from GABAergic diagonal band neurons. It is proposed that interneurons in the perinuclear zone serve as a relay station for information transfer from the ventral diagonal band to the SON.
Monoclonal antibody to neurofilament protein (SMI‐32) labels a subpopulation of pyramidal neurons in the human and monkey neocortex
Authors: Campbell Michael J. , Morrison John H. 
Published: January 2005

AbstractA monoclonal antibody that recognizes a nonphosphorylated epitope on the 168 kDa and 200 kDa subunits of neurofilament proteins has been used in an immunohistochemical study of cynomolgus monkey (Macaca fascicularis) and human neocortex. This antibody, SMI‐32, primarily labels the cell body and dendrites of a subset of pyramidal neurons in both species. A greater proportion of neocortical pyramidal neurons were SMI‐32 immunoreactive (ir) in the human than in the monkey. SMI‐32‐ir neurons exhibited consistent differences in the intensity of their immunoreactivity that correlated with cell size. The cellular specificity of SMI‐32 immunoreactivity suggests that a subpopulation of neurons can be distinguished on the basis of differences in the molecular characteristics of basic cytoskeletal elements such as neurofilament proteins.The size, density, and laminar distribution of SMI‐32‐ir neurons differed substantially across neocortical areas within each species and between species. Differences across cortical areas were particularly striking in the monkey. For example, the anterior parainsular cortex had a substantial population of large SMI‐32‐ir neurons in layer V and a near absence of any immunoreactive neurons in the supragranular layers. This contrasted with the cortical area located more laterally on the superior temporal gyrus, where layers III and V contained substantial populations of large SMI‐32‐ir neurons. Both areas differed significantly from the posterior inferior temporal gyrus, which was distinguished by a bimodal distribution of large SMI‐32‐ir neurons in layer III. Differences across human areas were less obvious because of the increase in the number of SMI‐32‐ir neurons. Perhaps the most notable differences across human areas resulted from shifts in the density of the larger SMI‐32‐ir neurons in deep layer III. A comparison between the species revealed that isocortical areas exhibited greater differences in their representation of SMI‐32‐ir neurons than primary sensory or transitional cortical areas. A comparison of distribution patterns of SMI‐32‐ir neurons across monkey cortical areas and data available on the laminar organization of cortical efferent neurons suggests that a common anatomic characteristic of this chemically identified subpopulation of neurons is that they have a distant axonal projection. Such correlations of cell biological characteristics with specific elements of cortical circuitry will further our understanding of the molecular and cellular properties that are critically linked to a given neuron's role in cortical structure and function.
Distribution of calcitonin gene‐related peptide‐like immunoreactivity in the nucleus ambiguus of the cat
Authors: McWilliam P. N. , Maqbool A. , Batten T. F. C. 
Published: January 2005

AbstractThe distribution of calcitonin gene‐related peptide (CGRP) in the cat nucleus ambiguus was examined by means of a combination of horseradish peroxidase (HRP) tracing and immunohistochemical techniques. Vagal motoneurones in the nucleus ambiguus were identified by applying HRP to either the thoracic vagus or the superior laryngeal nerve or the cervical vagus.Motoneurones in the nucleus ambiguus labelled with HRP from the thoracic vagus did not contain CGRP‐like immunoreactivity although CGRP‐like immunoreactive cells were present in this nucleus on the same sections. In contrast, a large proportion of the motoneurones labelled from the superior laryngeal nerve and a smaller proportion of cells labelled from the cervical vagus did contain CGRP‐like immunoreactivity.It is concluded that CGRP‐like immunoreactivity is absent from vagal preganglionic motoneurones projecting to structures in the thorax and abdomen but is present in vagal motoneurones projecting to striated muscle of the larynx and pharynx.
Organization of the projection from the superficial to the deep layers of the hamster's superior colliculus as demonstrated by the anterograde transport of Phaseolus vulgaris leucoagglutinin
Authors: Rhoades Robert W. , Mooney Richard D. , Rohrer William H. , Nikoletseas Michael M. , Fish Steven E. 
Published: January 2005

AbstractAnterograde tracing with Phaseolus vulgaris leucoagglutinin (PHA‐L) was employed to describe the projection from the superficial to the deep layers of the hamster's superior colliculus (SC). Deposits of PHA‐L in the stratum griseum superficiale (SGS) resulted in labelled terminal swellings in the stratum opticum and all of the deep laminae (the stratum griseum intermediate [SGI], stratum album intermedium [SAI], stratum griseum profundum [SGP], and stratum album profundum [SAP]). Labelled terminals were also visible in the periaqueductal gray (PAG). Reconstructions of individual axons showed that many collaterals in the deep laminae arose from axons that projected to targets outside the colliculus.The projection from the superficial to the deep laminae had a loose topographic organization, and the trajectories of interlaminar axons were generally deflected laterally from “projection” lines that were orthogonal to the SC surface. Physiological recording and receptive field mapping were used to determine actual projection lines, which connect neurons in the superficial and deep layers that have receptive fields with the same elevation. These projection lines closely matched the trajectory of the pathway from the superficial to the deep laminae.
ON/OFF organization in the cat lateral geniculate nucleus: Sublaminae vs. columns
Authors: Bowling D. B. , Caverhill J. I. 
Published: January 2005

AbstractThe hypothesis was tested that ON and OFF cells in the A layers of the cat's lateral geniculate nucleus (l.g.n.) form separate ON and OFF columns, and new evidence for their sublaminar distributions is presented. Evidence for columns was sought in previously published results from 184 electrode tracks oriented parallel to the layers and in new experiments, based on multiple, closely spaced electrode tracks oriented vertically to the layers. The tracks parallel to the layers were analyzed in two ways. First, the distances between cells of like‐sign and unlike‐sign were measured. Second, the signs of response of cells above and below one another, from pairs of tracks made simultaneously in the same layer, were compared. The analyses, which included computer simulations of the experiments based on columnar and noncolumnar models, provided no evidence for columns. The results from the closely spaced, vertical tracks also failed to show columns but confirmed that the organization of ON and OFF cells in the layers is fundamentally sublaminar.
Vasopressin‐ and proctolin‐like immunoreactive efferent neurons in blowfly abdominal ganglia: Development and ultrastructure
Authors: Nässel Dick R. , Holmqvist Bo I. , Movérus Börje J. A. 
Published: January 2005

AbstractIn the neural sheath of the fused thoracicoabdominal ganglia of the blowfly Calliphora erythrocephala, extensive neurohaemal areas can be seen in the electron microscope. A separate set of neurohaemal areas located in the sheath of the lateral abdominal nerve roots contain neural terminals of at least three morphological types. To determine which bioactive substances are stored and possibly released from the neurons supplying these neurohaemal areas, we applied a large number of antisera raised against different neuropeptides of invertebrate and mammalian type. Antisera to two types of neuropeptides react with neurons innervating the sheath of the abdominal nerve roots: antisera to lysine‐vasopressin and proctolin. There are only 14–24 vasopressin‐like immunoreactive (VPLI) neurons in the entire nervous system of Calliphora. These are all restricted to a bilateral cluster in the fused abdominal ganglia. From this cluster, the neurohaemal areas in abdominal nerve roots are supplied. Proctolin‐like immunoreactivity (PLI) can be seen in a large number of neurons in the nervous system of blowflies. The supply of PLI terminals to the abdominal nerve roots is from 12 to 14 neurons in a bilateral cluster of abdominal PLI neurons. It is clear from light‐ and electron‐microscopic immunocytochemistry that the two antisera label two separate populations of neurons that form overlapping terminals in the neural sheath. The immunoreactive terminals are located just below the permeable acellular basal lamina of the neural sheath. Hence, it is likely that at least two different bioactive peptides can be released neurohormonally into the circulation. An additional set of four efferent PLI neurons send axons into the medial abdominal nerve. These do not form neurohaemal terminals in the nerve root, but may innervate the hindgut.Also in the larval nervous system, VPLI and PLI neurons can be recognized. In the larva, the peptide‐containing neurons are segmentally arranged. The 14 larval VPLI neurons supply segmental abdominal nerves with axons that run inside the nerves to their targets. During metamorphosis, the segmental nerves fuse and the VPLI axons invade the neural sheath where they arborize and form varicose terminals. About the same number of PLI neurons could be detected in the abdominal ganglia of larval and adult flies. Only for a set of four caudal PLI neurons could efferent axons be traced in the larva. These axons run inside the medial abdominal nerves. The same four PLI neurons, with the same axonal projections, can be recognized in the adults.
Convergence and divergence in the afferent projections to cat area 17
Authors: Salin P. A. , Bullier J. , Kennedy H. 
Published: January 2005

AbstractWe have examined the topography of the afferent connections to area 17 in the cat by means of double retrograde label tracing techniques. Injections of two fluorescent retrograde tracers, diamidino yellow and fast blue, were made with variable separations in area 17 and the spatial distributions of the resulting populations of labeled cells examined in afferent cortical areas and subcortical structures.When injections were separated rostrocaudally, the topographic organizations of the projections were characterized quantitatively with two graphic methods: the labeling density curve and the connectivity graph. The labeling density curve measures labeled neuron density in successive rostrocaudal sections, whereas the connectivity graph provides a two‐dimensional model of the topography of a given connectivity. The connectivity graph makes it possible to define two parameters that characterize the topography of the connection: the convergence and the divergence. The convergence is defined as the extent of an afferent structure that contains neurons converging on a line normal to the cortical surface in area 17. The divergence is the extent of area 17 that is innervated by neurons contained in an infinitely small region of the afferent structure.The results show that a number of subcortical structures project to area 17 in a nontopographic manner, i.e., that in each of these structures neurons contained in an infinitely small region send projections to the whole of area 17 and that a line normal to the surface of area 17 is innervated by neurons distributed throughout the afferent structure in question. Nontopographic projections are found from the intralaminar nuclei, the ventral mesencephalic tegmental region, the diagonal band of Broca, and the locus coeruleus.All remaining subcortical structures and cortical areas send topographically organized projections to area 17. The extent of the convergence and divergence, however, varies between structures. Only the projection from the A laminae of the LGN was found to approximate a point‐to‐point projection with a convergence of 0.4 mm and 2 mm in divergence. Much larger convergence and divergence values are found in the projections from the claustrum and the cortical areas. For example, the divergence reaches 20 mm for the projections from area 20 or from the anterior part of the lateral suprasylvian sulcus.Knowing the convergence and divergence values and the retinotopic organizations of area 17 and a number of its afferents, it becomes possible to test whether connections in the visual system link regions representing the same zone of the visual field. This is the case for the geniculostriate projection only and does not apply for any of the other topographically organized afferents to area 17. For example, the region of area 18 containing neurons projecting to a line normal to the surface of area 17 represents 15 degrees of visual angle, whereas the neurons empaled by this line in area 17 represent only 5 degrees of visual angle.
Neuronal overload in the developing anuran lateral motor column in response to limb removal and thyroid hormone
Authors: Goldberg Joseph F. , Pollack Emanuel D. 
Published: January 2005

AbstractThe lateral motor column (LMC) in the anuran spinal cord normally undergoes a dramatic reduction in motor neuron number during development. At least two factors influence this process: the limb target which is required for the progression of cell loss, and thyroid hormone, a requisite for metamorphosis. This study has examined the relative and combined effects of limb amputation and exogenous thyroxine, initiated at the onset of normal rapid cell loss in Rana pipiens tadpoles, in regulating neuron number in the lumbosacral LMC.Thyroxine treatment or unilateral limb amputation temporarily resulted in significantly more LMC neurons than in untreated controls. Extraordinary numbers of motor neurons persisted through metamorphic climax when both treatments were combined. Population sizes frequently exceeded the maximum number of neurons observed prior to the onset of natural cell loss. Moreover, thyroxine‐treated tadpoles contained increased numbers of mitotic figures in the ventricular zone of the spinal cord and significantly more newly generated cells in the LMC, as revealed by 3H‐thymidine autoradiography.These findings suggest that thyroxine‐potentiated mitogenesis promotes greater numbers of new motor neurons to the LMC while, simultaneously, target removal delays the loss of extant cells. It is proposed that this interaction effectively maintains an immature state in the LMC so that neuronal “decisions” for survival and the consequent loss of target‐deprived neurons are postponed far longer than previously reported.
HRP study of the central components of the trigeminal nerve in the larval sea lamprey: Organization and homology of the primary medullary and spinal nucleus of the trigeminus
Authors: Anadón Ramón , De Miguel Encarnacion , Gonzalez‐Fuentes M. Jose , Rodicio Celina 
Published: January 2005

AbstractThe medullary and spinal connections of the trigeminal nerve of larval sea lampreys Petromyzon marinus were studied by anterograde and retrograde HRP transport after application into the orbit. Three components were found, all of them ipsilateral: (1) The motor nucleus was undivided in the larva, and its neurons possessed a rich dendritic tree. The single motor root was well separated from the sensory root. (2) The descending root was laterally located, and its fibers ran compactly to spinal levels. (3) Most medullary and many rostral spinal dorsal cells were labeled. Dorsal cells, which were mostly multipolar, had numerous mutual contacts. Some dorsal cell processes contacted the fourth ventricle. The name “primary medullary and spinal nucleus of the trigeminal nerve” (PMSV) is proposed for these dorsal cells. Medullary dorsal cells were not labeled by applying HRP at the level of spinal nerves, but application to the vagus nerve did label some. The possible relationship of this nucleus with the mesencephalic trigeminal nucleus of jawed vertebrates is discussed.
Nerve growth factor receptor and choline acetyltransferase colocalization in neurons within the rat forebrain: Response to fimbria‐fornix transection
Authors: Batchelor Peter E. , Armstrong David M. , Blaker Scott N. , Gage Fred H. 
Published: January 2005

AbstractAlthough it is well known that magnocellular cholinergic basal forebrain neurons are trophically responsive to nerve growth factor (NGF) and contain NGF receptors (NGFr), the exact distribution of forebrain NGFr‐immunoreactive neurons and the degree to which cholinergic neurons are colocalized with them have remained in question. In this study we employed a very sensitive double‐labelling method and examined in the same tissue section the distribution and cellular features of NGFr‐positive and choline acetyltransferase (ChAT)‐immunolabelled neurons within the rat basal forebrain. Throughout this region the majority of magnocellular basal forebrain neurons were immunoreactive for both NGFr and ChAT. However, a small percentage of neurons in the ventral portion of the vertical limb of the diagonal band of Broca were immunoreactive only for NGFr, whereas a larger population of magnocellular neurons in the substantia innominata exhibited only ChAT immunoreactivity. No NGFr‐immunoreactive cells were found associated with ChAT‐positive neurons in the striatum, neocortex, or hippocampus, and no single‐labelled NGFr‐immunoreactive neurons were found outside the basal forebrain area, except for a large number of positive‐labelled cells along the ventricular walls of the third ventricle.In addition to its function in maintaining the normal integrity of the basal forebrain and cholinergic, peripheral sympathetic, and neural‐crest‐derived sensory neurons, NGF may also have a role in the growth of these neurons after damage to the nervous system. To examine this postulate the hippocampus was denervated of its septal input and examined 8 weeks later. Two populations of neurons were found to have undergone collateral sprouting—namely, the midline magnocellular cholinergic neurons of the dorsal hippocampus and the sympathetic noradrenergic neurons of the superior cervical ganglion. Both of these neuronal populations also stained strongly for NGFr. In contrast, the small intrinsic cholinergic neurons of the hippocampus exhibited neither sprouting response nor staining for NGFr. In view of these results, we suggest that the differing sprouting responses demonstrated by these three neuronal populations may be due to their responsiveness to NGF, as indicated by the presence or absence of NGF receptors.