bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructural and immunocytochemical characterization of primary afferent terminals in the rat cuneate nucleus
Authors: De Biasi S. , Vitellaro‐Zuccarello L. , Bernardi P. , Valtschanoff J. G. , Weinberg R. J. 
Published: January 2005

AbstractThe cuneate nucleus is a relay center for somatosensory information by receiving tactile and proprioceptive inputs from primary afferent fibers that ascend in the dorsal funiculus. The morphology, synaptic contacts, and neurochemical content of primary afferent terminals in the cuneate nucleus of rats were investigated by combining anterograde transport of horseradish peroxidase conjugated to wheat‐germ agglutinin or to cholera toxin (injected in cervical dorsal root ganglia) with postembedding immunogold labeling for glutamate and GABA. Both tracers gave similar results. Two types of terminals were labeled: type I terminals were irregularly shaped, had a mean area of 4.0 μm2, synapsed on several dendrites, and were contacted by other terminals, some of which were GABA positive. Type II terminals were dome‐shaped, had a mean area of 2.18 μm2, and made synaptic contact on a single dendrite. All the anterogradely labeled terminals (interpreted as endings of primary afferents) were enriched in glutamate but not in GABA. The finding that identified primary afferent terminals are enriched in glutamate with respect to other tissue profiles strongly suggests a neurotransmitter role for glutamate in this afferent pathway to the rat cuneate nucleus. © 1994 Wiley‐Liss, Inc.
Ultrastructural and immunocytochemical analysis of the circuitry of two putative directionally selective ganglion cells in turtle retina
Authors: Guiloff Gloria D. , Kolb Helga 
Published: January 2005

AbstractTwo well‐stained, horseradish peroxidase‐filled varieties of putative ON‐OFF directionally selective ganglion cells, G14a and G15, that project to the dorsolateral optic tectum (Guiloff and Kolb [1992a] Vis. Neurosci. 8:295–313) were studied qualitatively and quantitatively. Both were bistratified ganglion cells with one tier of dendrites; in the OFF sublamina and the other in the ON sublamina of the inner plexiform layer (IPL). The cells were serially sectioned and examined for synaptic inputs by electron microscopy. Portions of the dendritic trees were also analyzed after postembedding immunocytochemistry for neurotransmitter candidates gamma aminobutyric acid (GABA), glycine, choline acetyltransferase (ChAT), and glutamate in presynaptic neurons.Both G14a and G15 are dominated by amacrine cell inputs and have only minor bipolar cell involvement. Probably at least two different types of bipolar cell are presynaptic. Both ganglion cells receive some GABA‐Positive (GABA+) amacrine inputs and G14a receives ChAT+ amacrine inputs. Glycine+, and glutamate+ inputs could not be detected in either cell. The GABA+ inputs appeared to be regionally arranged in the dendritic trees. The general distribution of amacrine and bipolar inputs to the two tiers of dendrites in both cell types appeared to be asymmetrical, both along the radial extent of the dendritic trees and within the depth of the IPL.Our data support some aspects of the current models for directional selectivity. We suggest candidate bipolar and amacrine cells that could have input to these ganglion cells. Since many of the putative presynaptic amacrine cells coincide with directionally selective types recorded and stained, by other authors, we propose that in turtle retina directional selectivity arises in neurons presynaptic to the ganglion cells. © 1994 Wiley‐Liss, Inc.
Spinal cord lamina V and lamina VII interneuronal projections to sympathetic preganglionic neurons
Authors: Cabot J. B. , Alessi V. , Carroll J. , Ligorio M. 
Published: January 2005

AbstractThis light and electron microscopic study sought to localize spinal cord interneurons that contribute to the normal and abnormal physiological regulation of spinal sympathetic preganglionic function. Sympathetic preganglionic neurons in caudal C8 through T4 of rat spinal cord were retrogradely labeled with wheat germ agglutinin (WGA) and/or cholera β subunit (CTβ) following injections into the superior cervical ganglion (SCG). With two exceptions, the observed locations of retrogradely VVGA‐ and CTβ‐labeled sympathetic preganglionic neurons were as expected from previous studies. The exceptions were restricted populations of cells in caudal C8 and rostral T1 spinal segments. These neurons were classified as ventrolateral (vlSPN) and ventromedial (vmSPN) sympathetic preganglionic neurons; their somata and dendrites encircled dorsolateral lamina IX motoneurons. Only WGA was transported transneuronally following the retrograde labeling of sympathetic preganglionic neurons. Transneuronally WGA‐labeled spinal interneurons were located principally in the reticulated division of lamina V and dorsolateral lamina VII. A strict segmental organization was observed. All transneuronally labeled interneurons were ipsilateral to, and coextensive with, retrogradely WGA‐labeled sympathetic preganglionic neurons. Electron microscopic observations suggested that retrograde transsynaptic passage of WGA occurred within the sympathetic preganglionic neuropil and showed further that similar classes of organelles were WGA immunoreactive in retrogradely labeled sympathetic preganglionic neurons and in transneuronally labeled lamina V and lamina VII neurons: (1) cisternae and vesicles at the trans face of the Golgi apparatus, (2) large endosomes/dense bodies, and (3) multivesicular bodies. The data are consistent with two hypotheses: (1) Somatic and visceral primary afferent inputs to thoracic spinal cord modify segmental sympathetic preganglionic function through activation of a disynaptic pathway involving lamina V and/or lamina VII interneurons, and (2) long‐loop propriospinal pathways access sympathetic preganglionic neurons through symmetrical, segmental interneuronal circuitry. © 1994 Wiley‐Liss, Inc.
Effects of denervation upon receptor cell survival and basal cell proliferation in tuberous electroreceptor organs of a weakly electric fish
Authors: Weisleder Pedro , Lu Ying , Zakon Harold H. 
Published: January 2005

AbstractWeakly electric fish generate electric fields for the purposes of electrolocation and communication. These fields are detected by specialized receptor organs: the tuberous organs. In the present study we investigated the effects of denervation upon receptor cell survival and progenitor (basal) cell proliferation rate. The left, infraorbital, anterior lateral line nerve of brown ghosts (Apteronotus leptorhynchus) was sectioned, and the proximal stump was dipped in ricin to prevent regrowth. In groups of four, the animals were given two daily injections of the cell proliferation marker bromodeoxyuridine (BrdU) for 2 days at 1, 2, 3, or 4 weeks following denervation. At the completion of the BrdU injection schedule, a piece of cheek skin, rostroventral to the eye, was removed from the left (denervated) and the right (intact) sides and processed for light microscopy or immunocytochemistry. Our results show: (1) there is progressive receptor cell death and tuberous organ degeneration following denervation; (2) basal cell proliferation increases steadily with time after denervation and tuberous organ degeneration; and (3) despite denervation, some proliferating basal cells differentiate into receptor cells, but these new receptor cells eventually die. These results suggest that innervation is essential for tuberous electroreceptor cell survival and that the rate at which basal cells proliferate is regulated by receptor cell health, locally released factors, or both. © 1994 Wiley‐Liss, Inc.
Organization of projections from the ventromedial nucleus of the hypothalamus: A Phaseolus vulgaris‐Leucoagglutinin study in the rat
Authors: Canteras N. S. , Simerly R. B. , Swanson L. W. 
Published: January 2005

AbstractThe organization of projections from the four parts of the ventromedial nucleus (VMH) and a ventrolaterally adjacent region tentatively identified as the tuberal nucleus (TU) have been analyzed with small injections of the anterograde axonal tracer Phaseolus vulgaris‐leucoagglutinin (PHA‐L). Extrinsic and intranuclear projections of each part of the VMH display clear quantitative differences, whereas the overall patterns of outputs are qualitatively similar. Overall, the VMH establishes massive intrahypothalamic terminal fields in other parts of the medial zone, tending to avoid the periventricular and lateral zones. The ventrolateral VMH is more closely related to other parts of the hypothalamus that also express gonadal steroid hormone receptors, including the medial preoptic, tuberal, and ventral premamillary nuclei, whereas other parts of the VMH are more closely related to the anterior hypothalamic and dorsal premammillary nuclei. All parts of the VMH project to the zona incerta (including the A13 region) and parts of the midline thalamus, including the paraventricular and parataenial nuclei and nucleus reuniens. The densest inputs to the septum are to the bed nuclei of the stria terminalis, where the ventrolateral and central VMH innervate the anteroventral and anterodorsal areas and transverse and interfascicular nuclei, whereas the anterior and dorsomedial VMH innervate the latter two. The central, lateral, and medial amygdalar nuclei receive substantial inputs from various parts of the VMH. Other regions of the telencephalon, including the nucleus accurmbens and the piriform‐amygdaloid, infralimbic, prelimbic, anterior cingulate, agranular insular, piriform, perirhinal, entorhinal, and postpiriform transition areas, also receive sparse inputs. All parts of the VMH send a massive, topographically organized projection to the periaqueductal gray. Other brainstem terminal fields include the superior colliculus, peripeduncular area, locus coeruleus, Barrington's nucleus, parabrachial nucleus, nucleus of the solitary tract, and the mesencephalic, pontine, gigantocellular, paragigantocellular, and parvicellular reticular nuclei.The projections of the TU are similar to, and a subset of, those from the VMH and are thus not nearly as widespread as those from adjacent parts of the lateral hypothalamic area. Because of these similarities, the TU may eventually come to be viewed most appropriately as the lateral component of the VMH itself. The functional implications of the present findings are discussed in view of evidence that the VMH plays a role in the expression of ingestive, affective, and copulatory behaviors. © 1994 Wiley‐Liss, Inc.
Postnatal development of parvalbumin immunoreactivity in the cerebral cortex of the cat
Authors: Alcántara Soledad , Ferrer Isidro 
Published: January 2005

AbstractParvalbumin immunoreactivity in the developing neocortex of the cat progresses following specific laminar, areal, and, in a particular area, roughly anteroposterior gradients. Parvalbumin immunoreactivity first occurs in basket cells and later in chandelier neurons. Pyramid‐like immunoreactive neurons are also transitorily observed from the second to the third week in layer V of the auditory association‐related areas. Parvalbumin‐immunoreactive neurons first appear in the primary somatosensory cortex and primary auditory and visual areas, followed by the primary motor and polysensory association areas and, finally, the auditory association areas and cortical areas related to the limbic system.In addition to cortical neurons, three fiber systems are immunolabeled with antiparvalbumin antibodies: thalamocortical, callosal, and ipsilateral corticocortical. Parvalbumin‐immunoreactive thalamocortical fibers appear during the first month of postnatal life. Parvalbumin‐immunoreactive callosal and ipsilateral corticocortical fibers are seen from the fourth postnatal week onward. Because all parvalbumin‐immunoreactive cortical neurons in adulthood are nonpyramidal inhibitory cells, the present findings suggest that a number of ipsilateral corticocortical and callosal connections may be inhibitory. © 1994 Wiley‐Liss, Inc.
Nitric oxide synthase in the brain of the turtle Pseudemys scripta elegans
Authors: Brüning Gerold , Wiese Stephanie , Mayer Bernd 
Published: January 2005

AbstractThe distribution pattern of nitric oxide synthase (NOS) was investigated in the brain of the turtle by NADPH‐diaphorase histochemistry. The specificity of the histochemical staining was tested by immunocytochemical colocalization with an antiserum specific for NOS. In the forebrain, neurons staining intensely for nitric oxide synthase were localized in the olfactory tubercle, the basal ganglia complex, the basal amygdaloid nucleus, suprapeduncular nucleus, and the posterior hypothalamic area. Many positive fibers course in a tract connecting the basal amygdaloid nucleus with the hypothalamus, corresponding to the stria terminalis. Bundles of nitroxergic fibers were seen to course at the ventromedial edge of the optic tract and to cross in the supraoptic decussation, apparently consisting of tectothalamic and thalarnotectal fibers. In the midbrain, strongly NOS‐positive neurons were present in the substantia nigra, the nucleus profundus mesencephali, the periventricular grey of the optic tectum, the laminar nucleus of the torus semicircularis, and the nucleus of the lateral lemniscus. The area of the locus coeruleus harbored an accumulation of intensely stained neurons, which, as n mammals, might represent a cholinergic cell group of the reptilian brainstem. In the cerebellum, strong staining was confined to bundles of afferent fibers running in the lower molecular and in the Purkinje cell layer. These axons appeared to include ascending projections from the dorsal funicular nucleus or the spinal cord. NOS‐positive cells in the caudal Brainstem were found in the cerebellar nuclei, in the superior vestibular nucleus, in the reticular nuclei, ventrolateral to the nucleus of the solitary tract, in the perihypoglossal, and in the dorsal funicular nucleus. Taken together, these results suggest that nitric oxide acts as a messenger molecule in different areas of the reptilian brain and spinal cord. In certain areas, the pattern of expression of NOS appears to have evolved before radiation of present mammalian, avian, and reptilian species. © 1994 Wiley‐Liss, Inc.
Topography of developing thalamic and cortical pathways in the visual system of the cat
Authors: Kennedy H. , Salin P. , Bullier J. , Horsburgh G. 
Published: January 2005

AbstractAdult patterns of connectivity could emerge during development by a process of selective elimination from an earlier, more widespread, connectivity. We have addressed this issue by examining the topography of developing projections to area 17 in the cat. At different postnatal ages, paired injections of the retrograde tracers diamidino yellow and fast blue were made in area 17. Interinjection separations were carefully controlled and the spatial distribution of the two populations of labelled neurones investigated.Projections to the striate cortex from the lateral geniculate nucleus, area 18, as well as connections intrinsic to area 17 were analysed quantitatively with a graphic method that uses a two‐dimensional model of the projection. This allows two parameters of the projection to be calculated: the divergence (the spatial extent of area 17 contacted by an infinitely small region of an afferent structure) and the convergence (the extent of an afferent structure that projects to an infinitely small region of area 17).During postnatal development, the bulk of the connections making up the geniculostriate and corticocortical pathways showed no variation either in their convergence and divergence. However, the projection of area 18 to area 17 and the intrinsic area 17 connections (but not the geniculostriate projection) in the 3–15‐day‐old kittens were each found to contain a small subpopulation of widely scattered neurones with widespread axonal trajectories.These results, showing that many initially formed connections display a high degree of topographical order, are discussed in terms of the control mechanisms specifying axonal trajectories during development. © 1994 Wiley‐Liss, Inc.
Visual pontocerebellar projections in the macaque
Authors: Glickstein Mitchell , Gerrits Nico , Kralj‐Hans Ines , Mercier Barbara , Stein John , Voogd Jan 
Published: January 2005

AbstractThe cerebellum plays an important role in the visual guidance of movement. In order to understand the anatomical basis of visuomotor control, we studied the projection of pontine visual cells onto the cerebellar cortex of monkeys. Wheat germ agglutinin horseradish peroxidase was injected into the dorsolateral pons of two monkeys. Retrogradely labelled cells were mapped in the cerebral cortex and superior colliculus, and orthogradely labelled fibers in the cerebellar cortex. The largest number of retrogradely labelled cells in the cerebral cortex was in a group of medial extrastriate visual areas. The major cerebellar target of these dorsolateral pontine cells is the dorsal paraflocculus. There is a weaker projection to the uvula, paramedian lobe, and Crus II, and a sparse but definite projection to the ventral paraflocculus. There are virtually no projections to the flocculus. There are sparse ipsilateral pontocerebellar projections to these same regions of cerebellar cortex.In nine monkeys, we made small injections of the tracer into the cerebellar cortex and studied the location of retrogradely filled cells in the pontine nuclei and inferior olive. Injections into the dorsal paraflocculus or rostral folia of the uvula retrogradely labelled large numbers of cells in the dorsolateral region of the contralateral pontine nuclei. Labelled cells were found ipsilaterally, but in reduced numbers. Injections outside of these areas in ventral paraflocculus or paramedian lobule labelled far fewer cells in this region of the pons. We conclude that the principal source of cerebral cortical visual information arises from a medial group of extrastriate visual areas and is relayed through cells in the dorsolateral pontine nuclei. The principal target of pontine visual cells is the dorsal paraflocculus. © 1994 Wiley‐Liss, Inc.
Implants of polymer‐encapsulated human NGF‐secreting cells in the nonhuman primate: Rescue and sprouting of degenerating cholinergic basal forebrain neurons
Authors: Emerich Dwaine F. , Winn Shelley R. , Harper James , Hammang Joseph P. , Baetge E. Edward , Kordower Jeffrey H. 
Published: January 2005

AbstractBaby hamster kidney (BHK) cells were genetically modified to secrete high levels of human nerve growth factor (BHK‐hNGF). Following polymer encapsulation, these cells were implanted into the lateral ventricle of four cynomolgus monkeys immediately following a unilateral transection/aspiration of the fornix. Three control monkeys received identical implants, with the exception that the BHK cells were not genetically modified to secrete hNGF and thus differed only by the hNGF construct. One monkey received a fornix transection only. All monkeys displayed complete transections of the fornix as revealed by a comprehensive loss of acetylcholinesterase‐containing fibers within the hippocampus ipsilateral to the lesion. Control monkeys that were either unimplanted or received BHK‐control (non‐NGF secreting) cell implants did not differ from each other and displayed extensive losses of choline acetyltransferase and p75 NGF receptor (NGFr)‐immunoreactive neurons within the medial septum (MS; 53 and 54%, respectively) and vertical limb of the diagonal band (VLDB; 21 and 30%, respectively) ipsilateral to the lesion. In contrast, monkeys receiving implants of BHK‐hNGF cells exhibited a only a modest loss of cholinergic neurons within the septum (19 and 20%, respectively) and VLDB (7%). Furthermore, only implants of hNGF‐secreting cells induced a dense sprouting of cholinergic fibers within the septum, which ramified against the ependymal lining of the ventricle adjacent to the transplant site. Examination of the capsules retreived from monkeys just prior to their death revealed an abundance of cells that produced detectable levels of hNGF in a sufficient concentration to differentiate PC12A cells in culture. These findings support the use of polymer‐encapsulated cell therapy as a potential treatment for neurodegenerative diseases such as Alzheimer disease where basal forebrain degeneration is a consistent pathological feature. Moreover, this encapsulated xenogeneic system may provide therapeutically effective levels of a number of neurotrophic factors, alone or in combination, to select populations of neurons within the central nervous system. © 1994 Wiley‐Liss, Inc.
Analysis of gamma‐aminobutyric acidergic synaptic contacts in the thalamic reticular nucleus of the monkey
Authors: Williamson Andrew M. , Ohara Peter T. , Ralston Diane D. , Milroy Antonia M. , Ralston Henry J. 
Published: January 2005

AbstractGamma‐aminobutyric acidergic (GABAergic) neurons in the thalamic reticular nucleus (TRN) spontaneously generate a synchronous bursting rhythm during slow‐wave sleep in most mammals. A previous study at the electron microscopic level in cat anterior TRN has suggested that synchronous bursting activity could result from the large number of presumably GABAergic dendrodendritic synaptic contacts. However, little is known about the synaptology of the monkey thalamic reticular nucleus and whether it contains dendrodendritic contacts.To address this issue, we examined tissue obtained from Macaca fascicularis that was prepared for electron microscopy using postembedding techniques to demonstrate GABA immunoreactivity. Examination of the anterior (motor) and posterior (somatosensory) portions of the TRN disclosed the following: The majority of synaptic contacts (87.5% of 958) were formed by axon terminals showing no GABA immunoreactivity and making asymmetric synaptic contacts on dendrites or cell bodies. A further 6.4% of synaptic contacts was composed of GABA‐immunoreactive presynaptic terminals making symmetric contacts with the dendrites of TRN neurons. The majority resembled the pleomorphic vesicle containing F‐terminals seen in the dorsal thalamus and known to originate from axons of TRN. A subset or possible second class did not resemble any previously described class of GABA‐immunoreactive terminals in the TRN. Both classes of these terminals making symmetric contacts may originate wholly or partially within the nucleus. There was one dendrodendritic synaptic contact and only a small number (3.2%) of axodendritic contacts with synaptic vesicles visible both pre‐ and postsynaptically.We conclude that dendrodendritic contacts are probably not responsible for the synchronized bursting neuronal activity seen in the slow‐wave sleep of monkeys, and that, if TRN neurons are coupled synaptically, the most likely mechanism is through the synapses formed by recurrent axon collaterals of TRN neurons onto TRN dendrites. © 1994 Wiley‐Liss, Inc.