bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transient cortical pathways in the pyramidal tract of the neonatal ferret
Authors: Meissirel Claire , Dehay Colette , Kennedy Henry 
Published: January 2005

AbstractAnterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) was used to study transient axons from the visual cortex in the pyramidal tract. Injections at birth restricted to the visual cortex labeled axons in the vicinity of the pontine nuclei. Two to eight days after birth, axons from the occipital cortex were found posterior to the pontine nucleus, their caudalmost stable target. Transient corticospinal axons from the presumptive primary visual cortex did not grow caudal to the pyramidal decussation. Innervation of more distal targets preceded innervation of proximal targets. Innervation of the pontine nucleus is initiated around 68 hours after birth, when the transient extension in the medullary pyramidal tract has attained its maximum caudal extent. Innervation of the superior colliculus begins 9 days after birth.Retrograde tracers were used to follow the developmental changes in the cortical distribution of the parent neurons giving rise to axons in the pyramidal tract. In the adult, labeled neurons following injection of retrograde tracer in the pyramidal tract occupied less than a third of the neocortex and were centred on the anterior part of the coronal and spleniocruciate gyri. In the immature brain, labeled neurons covered more than two‐thirds of the neocortex. Areal density measurements in the neonate showed that peak labeling was centred in the anterior coronal and spleniocruciate gyri, where corticospinal cells in the adult are located. There was a marked rostral‐caudal gradient so that labeled neurons were very scarce towards the occipital pole.These results, showing transient neocortical axons in the pyramidal tract in a carnivore, suggest that this may be a common feature of mammalian development. The finding that the adult pattern of corticospinal projections does not emerge from a uniform distribution is discussed with respect to the areal specification of cortical connectivity. © 1993 Wiley‐Liss, Inc.
Recovery of original nerve supply after hypoglossal–facial anastomosis causes permanent motor hyperinnervation of the whisker‐pad muscles in the rat
Authors: Angelov Doychin N. , Gunkel Andreas , Stennert Eberhard , Neiss Wolfram F. 
Published: January 2005

AbstractHypoglossal–facial anastomosis (HFA), used in humans for the treatment of facial palsy, was experimentally performed in adult female Wistar rats. The time course of facial reinnervation and the extent of the new motor nerve supply of the vibrissal muscles that develops after HFA were estimated by counting all motoneurons in the brainstem labeled by injection of horseradish peroxidase (HRP) into the whisker pad; muscle innervation by motor endplates was not studied. In untreated animals, HRP injection labels 1,254 ± 54 (mean ± S.D.; n = 6) motoneurons, localized exclusively in the lateral subdivision of the facial nucleus. Immediately following HFA, this number drops to zero. The first HRP‐labeled motoneurons appear in the hypoglossal nucleus at 28 days postoperation (dpo) and at 56 dpo their number reaches 1,096 ± 48. Unexpectedly, the facial nerve, whose proximal stump has been left as blind end during surgery, additionally sends axons to the facial periphery. This resprouting is first detected at 42 dpo with HRP‐marked neurons throughout the facial nucleus lacking somatotopic organiza‐tion. The number of these labeled neurons also rises with time, and at 56 dpo, a total of 1,797 ± 142 facial and hypoglossal motoneurons, that is, 43% more motoneurons than in normal animals, supplies the whisker pad. This hyperinnervation, that is, the projection of more moto‐neurons into the target muscle than under normal conditions‐further increases to 1,978 ± 92 motoneurons at 224 dpo and may provide a new animal model for studying the competitive relationships between motoneurons in their search for peripheral targets. © 1993 Wiley‐Liss, Inc.
Retinal ganglion cells within the foveola of new world (Saimiri sciureus) and old world (Macaca fascicularis) monkeys
Authors: Leventhal Audie G. , Thompson Kirk G. , Liu Dan 
Published: January 2005

AbstractThe morphology and distribution of retinal ganglion cells within the foveola of New World (Saimiri sciureus) and Old World (Macaca fascicularis) monkeys labeled as a result of horseradish peroxidase injections into the dorsal lateral geniculate nucleus were studied. The results indicate that monkey's foveola normally contains significant numbers of retinal ganglion cells. Most of these project ipsilaterally. Cells within the foveola are larger than other cells in monkey central retina; their dendritic fields are up to 50 times larger in area than those of cells in the foveal slope. The dendritic fields of the ganglion cells within the foveola cover at least 70–100% of its area.Among ganglion cells within the foveola (as in most ganglion cells), there was a strong tendency for the axon and dendritic tree to arise from opposite poles of the soma. The axon‐dendrite axes of ganglion cells within the foveola did not show a consistent pattern. In contrast, the axes of ganglion cells in the transition zone between the foveola and the foveal slope were directed tangentially to the circumference of the fovea. The dendritic coverage of the foveola by retinal ganglion cells suggests functional significance and provides a possible neural basis for 2–3° of bilateral representation of the fovea within the central visual pathways. Alternatively or in addition, these cells may be “remnants of foveation” and provide insight into the developmental processes that mediate the development of the fovea. © 1993 Wiley‐Liss, Inc.
Development of corticotectal synaptic terminals in the cat: A quantitative electron microscopic analysis
Authors: Plummer Kim Lord , Behan Mary 
Published: January 2005

AbstractWe studied the development of corticotectal synaptic terminal boutons and synapses by making injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP) into area 17 of visual cortex in kittens ranging from newborn to 12 weeks of age and in adults. The location and extent of the injection site, and labeled corticotectal axon terminals in the superficial layers of the superior colliculus were demonstrated histochemically with the cobalt‐glucose oxidase diaminobenzidine reaction.During the first 2 weeks after birth, the majority of labeled profiles resembled axonal growth cones, or structures intermediate in morphology between growth cones and synaptic terminals, while very few corticotectal axon terminals forming well‐defined synaptic contacts were observed. Labeled synaptic terminals in kittens at 1 and 2 weeks of age were small, contained very few synaptic vesicles, which were usually restricted to the contact zone, and exhibited few mitochondria. By 4 and 6 weeks after birth, a well‐developed population of synaptic terminals was established; however, growth cones and intermediate profiles were still numerous. At 8 weeks of age synaptic terminals were morphologically mature, and growth cone‐like profiles were no longer observed.To study quantitative changes in synapse development we used the disector method to obtain unbiased estimates of the density and number of corticotectal synaptic terminals and synapses; both the density and number of terminals and synapses increased steadily throughout postnatal development. These results suggest that the corticotectal projection develops by the progressive elaboration of synapses, as opposed to synapse overproduction and subsequent elimination. © 1993 Wiley‐Liss, Inc.
Topological analysis of the brainstem of the bowfin, Amia calva
Authors: Heijdra Yvonne F. , Nieuwenhuys Rudolf 
Published: January 2005

AbstractThis paper presents a survey of the cell masses in the brainstem of the generalized actinopterygian fish Amia calva, based on transversely cut Nissl‐, Klüver‐Barrera‐, and Bodian‐stained serial sections. This study is intended to serve a double purpose. First it forms part of a now almost complete series of publications on the structure of the brainstem in representative species of all groups of vertebrates. Within the framework of this comparative program the cell masses in the brainstem and their positional relations are analyzed in the light of the Herrick–Johnston concept; according to this the brainstem nuclei are arranged in four longitudinal, functional zones or columns, the boundaries of which are marked by ventricular sulci. The procedure employed in this analysis essentially involves two steps: first, the cell masses and large individual cells are projected upon the ventricular surface, and next, the ventricular surface is flattened out, that is, subjected to a one‐to‐one continuous topological transformation (Nieuwenhuys [1974] J. Comp. Neurol. 156:255‐267). The second purpose of the present paper is to provide a cytoarchitectonic basis for experimental analysis of the fiber connectivity in the brainstem of Amia.Five longitudinal sulci–the sulcus medianus inferior, the sulcus intermedius ventralis, the sulcus limitans, the sulcus intermedius dorsalis, and the sulcus lateralis mesencephali–could be distinguished. Some shorter grooves, present in the isthmal region, clearly deviate from the overall longitudinal pattern of the other sulci. Although in Amia most neuronal perikarya are contained within a diffuse periventricular gray, 40 cell masses could be delineated: Eight of these are primary efferent or motor nuclei, 10 are primary afferent or sensory centers, seven are considered to be components of the reticular formation, and the remaining 15 may be interpreted as “relay” nuclei.The topological analysis yielded the following results. In the rhombencephalon the gray matter is arranged in four longitudinal columns or areas, termed area ventralis, area intermedioventralis, are intermediodorsalis, and area dorsalis. The sulcus intermedius ventralis, the sulcus limitans, and the sulcus intermedius dorsalis mark the bounderies between these morphological entities. These longitudinal areas coincide largely, but not entirely, with the functional columns of Herrick and Johnston. The most obvious incongruity is that the area intermediodorsalis contains, in addition to the viscerosensory nucleus of the solitary tract, several general somatosensory and special somatosensory nuclei. The four longitudinal zones cannot be distinguished in the mesencephalon nor can the sulcus limitans be recognized here. Functionally, however, the medial part of the tegmentum mesencephali may be considered the rostral extremity of the somatomotor column, whereas the remainder of the midbrain contains a number of somatosensory centers. © 1994 Wiley‐Liss, Inc.
Origin and function of spiral fibers projecting to the goldfish mauthner cell
Authors: Scott John W. , Zottoli Steven J. , Beatty Nicholas P. , Korn Henri 
Published: January 2005

AbstractTwo neuron types contact the Mauthner cell (M cell) in the axon cap, a specialized region of high electrical resistance surrounding the initial segment of the M cell axon. One type produces a mixed electrical and chemical inhibition of the M cell. The second sends axons into the central core of the axon cap, where they spiral around the initial segment making both conventional synapses and gap junction contacts. The origin and synaptic effects of these spiral fibers have not been studied previously.When goldfish M cells were filled with Lucifer yellow, presynaptic spiral fibers were seen in the axon cap. These fibers could be traced back through the medial longitudinal fasciculus to their somata, near the contralateral fifth nerve motor nucleus. The same somata were labeled by horseradish peroxidase injected extracellularly into the axon cap.Recordings were made in the axon cap and the M cell after stimulation of hindbrain areas near the spiral fiber somata and axons. Extracellularly, a negative potential was observed close to the termination of the spiral fibers and termed the spiral fiber potential (SFP). Intracellularly, a graded, short latency depolarization of the M cell corresponded to the SFP and could cause the M cell to spike. This depolarization did not shunt the membrane, indicating that it may be produced through gap junctions. Intracellular responses to hindbrain stimulation also had a chloride‐dependent, second component that shunted the membrane during paired‐pulse testing. This inhibitory second component was probably evoked by cells other than the spiral fiber cells themselves. © 1994 Wiley‐Liss, Inc.
Grafts of fetal central nervous system tissue rescue axotomized clarke's nucleus neurons in adult and neonatal operates
Authors: Himes B. Timothy , Goldberger Michael E. , Tessler Alan 
Published: January 2005

AbstractMany conditions are thought to contribute to neuron death after axotomy, including immaturity of the cell at the time of injury, inability to reestablish or maintain target contact, and dependence on trophic factors produced by targets. Exogenous application of neurotrophic factors and transplants of peripheral nerve and embryonic central nervous system (CNS) tissue temporarily rescue axotomized CNS neurons, but permanent rescue may require transplants that are normal targets of the injured neurons. We examined the requirements for survival of axotomized Clarke's nucleus (CN) neurons. Two months after hemisection of the spinal cord at the T8 segment, there was an ipsilateral 30% loss of neurons at the L1 segment in adult operates and a 40% loss in neonates. Transplants of embryonic spinal cord, cerebellum, and neocortex inserted into the T8 segment at the time of hemisection prevented virtually all of the cell death in both adults and neonates, but transplants of embryonic striatum were ineffective. None of the grafts prevented the somal atrophy of CN neurons caused by axotomy. Retrograde transport of fluoro‐gold from the cerebellum demonstrated that 33% of all CN neurons at L1 project to the cerebellum, 50% of these died following a T8 hemisection, but all these projection neurons were rescued by a transplant of embryonic spinal cord. These results suggest that the rescue of axotomized CN neurons is relatively specific for the normal target areas of these neurons, but this specificity is not absolute and may depend on the distribution and synthesis of particular neurotrophic agents. © 1994 Wiley‐Liss, Inc.
Light and electron microscopic analysis of synaptic development in Macaca monkey retina as detected by immunocytochemical labeling for the synaptic vesicle protein, SV2
Authors: Okada M. , Erickson A. , Hendrickson A. 
Published: January 2005

AbstractThe development of synapses has been followed in Macaca monkey fetal and infant retina using immunocytochemical labeling for the transmembrane synaptic vesicle glycoprotein, SV2. Electron microscopy (EM) was used to verify the presence of morphological synapses at selected ages. EM immunocytochemical labeling in adult retina showed that all synaptic types contained SV2 in inner (IPL) and outer (OPL) plexiform layers. In fetal retina, SV2 expression and the appearance of morphological synapses were closely related in time, demonstrating that SV2 is a reliable marker for synaptogenesis.SV2 expression appears along a foveal to peripheral gradient. Both SV2 and synapses appear in the foveal IPL at Fd50–55, and reach the retinal edge by Fd90–103. Cone ribbon synapses and SV2 labeling are not present in the foveal OPL until Fd60. Photoreceptors in the far periphery contain SV2 by Fd119–125. This pattern demonstrates an “inner to outer” direction of synaptogenesis. Cones show SV2 labeling before rods at the same retinal eccentricity. In the cone‐dominated fovea, SV2 labeling and bipolar cell ribbon‐containing terminals are present at Fd55 when amacrine cell conventional terminals are very scarce, indicating that bipolar synapses precede amacrine synapses in monkey foveal IPL. SV2 labeling and bipolar terminals appear first in the outer IPL which contains “OFF” ganglion and bipolar processes in the adult, suggesting that “OFF” midget bipolar cells may form the first synapses.Both SV2 immunocytochemical labeling and EM morphology find that monkey retina follows a generalized inner before outer, and cone before rod synaptic developmental pattern, similar to that in other mammals. The cone‐dominated fovea initiates synaptogenesis, and shows a different synaptic sequence from rod‐dominated peripheral retina. © 1994 Wiley‐Liss, Inc.
Evidence for a GABAergic interface between cortical afferents and brainstem projection neurons in the rat central extended amygdala
Authors: Sun Ning , Yi Hong , Cassell Martin D. 
Published: January 2005

AbstractThe synaptic circuitry of the intrinsic GABAergic system of the central extended amygdala (CEA) in relation to efferent neurons and cortical afferents was examined in the present study. Neurons in the CEA projecting to the dorsal vagal complex and the parabrachial complex were identified by the retrograde transport of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP). Postembedding GABA‐immunocytochemistry revealed that GABA‐immunoreactive (GABA‐IR) terminals formed largely symmetrical synaptic contacts with the perikarya and proximal dendritic processes of almost all WGA‐HRP‐labeled neurons in the CEA. To determine the relationship between cortical afferents and CEA GABAergic neurons, WGA‐HRP was used to anterogradely label afferents from the insular cortex in combination with postembedding immunogold detection of GABA. Cortical afferents formed asymmetrical synaptic contacts predominantly on small dendrites and dendritic spines. Many of the dendrites postsynaptic to cortical terminals in the central nucleus were immunoreactive for GABA although only relatively few spines were GABA‐IR. Combining pre‐embedding GAD‐immunocytochemistry with cortical lesions resulted in approximately 40% of degenerating terminals of insular cortical origin in the central nucleus in contact with small, GAD‐IR dendrites and spines.The present results demonstrate that the neurons providing the major CEA outputs to the brainstem receive an extensive GABAergic innervation, strongly supporting our proposal that CEA efferent neurons are under strong tonic inhibition by intrinsic GABAergic neurons. Further, our finding that the major cortical input to the central nucleus preferentially innervates intrinsic GABAergic neurons suggests that these neurons in the CEA may serve as an interface between the principal inputs and outputs of this forebrain region. © Wiley‐Liss, Inc.
New subdivision schema for the avian torus semicircularis: Neurochemical maps in the chick
Authors: Puelles Luis , Robles Carmen , Martínez‐de‐la‐Torre Margaret , Martínez Salvador 
Published: January 2005

AbstractChemoarchitectonic subdivisions in the chicken torus semicircularis were mapped by means of acetylcholinesterase histochemistry and immunocytochemical labeling of leucineenkephalin, choline acetyltransferase, neuropeptide Y, and calbindin/calretinin in adjacent sections. The torus semicircularis was found to consist of three main divisions: intercollicular area, torai nucleus, and preisthmic superficial area. All three appear variously subdivided. The intercollicular area is a mid‐mesencephalic ventral periventricular region and appears subdivided into core and shell intercollicular regions. The toral nucleus is formed by a large caudal periventricular cytoarchitectonic complex, consisting of a periventricular lamina subdivided into core and shell regions, a pericentral, diffuse external nucleus, a central nucleus subdivided into core and shell regions, a caudomedial shell nucleus, a paracentral nucleus, and a posterior hiliar nucleus, apart from other minor parcellations. The preisthmic superficial area extends superficially at the caudomedial end of the toral nucleus, reaching the paramedian dorsal brain surface just rostral to the isthmo‐optic nucleus. It is subdivided into core and shell regions. This previously unnoticed area is distinguished here from the intercollicular area and from the caudomedial shell and paracentral nuclei, all of which are frequently mixed in the literature under the concept “intercollicular nucleus.” The revised terminology and subdivision for the avian torus clarifies many chemoarchitectonic and hodological mappings reported in the literature. It also suggests new research subjects and eliminates some causes of confusion. © Wiley‐Liss, Inc.
NGF increases neuritic complexity of cholinergic interneurons in organotypic cultures of neonatal rat striatum
Authors: Studer Lorenz , Spenger Christian , Luthman Johan , Seiler Rolf Walter 
Published: January 2005

AbstractThe influence of NGF on cholinergic interneurons in organotypic roller tube cultures of 4 day postnatal rat striatum was examined after 13 to 16 days in vitro. Cultures were divided into four groups. The medium of the NGF treated group was supplemented with 5 ng/ml NGF, whereas control groups were cultured either without NGF, by adding 20 ng/ml neutralising anti‐NGF antibody, or by adding both NGF and anti‐NGF antibody to the medium. Two different cell populations were identified by an image analysis system which measured acetylcholinesterase staining intensity. It was demonstrated that NGF promotes survival of the large, intensely stained population. Eighty computer‐assisted reconstructions of intensely stained cells, 20 for each treatment group, were performed in a random order by means of a neuron tracing system. Axons and dendrites were analysed separately. © Wiley‐Liss, Inc.NGF enhanced complexity of neuritic, predominantly axonal trees by increasing the number of axonal segments by 91% to 100% (P < 0.01), the number of dendritic segments by 33% to 63% (P = 0.09 to P < 0.01), maximal axonal branch order by 37% to 50% (P < 0.05), and maximal dendritic branch order by 22% to 37% (P < 0.05). Further evidence of more complex neuritic trees was given by Sholl concentric sphere analysis. Anti‐NGF antibody could block all these effects. General rules of branching architecture were not affected by NGF treatment as shown by analysing mean segment length in relation to the branch order, branch point exit angles, total tortuosity, Rall's ratio, and tapering of neuritic trees. © Wiley‐Liss, Inc.
Expression of a keratan sulfate proteoglycan during development of the dorsal lateral geniculate nucleus in the ferret
Authors: Robson John A. , Geisert E. E. 
Published: January 2005

AbstractABAKAN is a keratan sulfate proteoglycan was identified in rat brain by monoclonal antibody TED15 (Geisert et al. [1992] Brain Res. 571:165–168). It blocks neuronal attachment and neurite outgrowth in culture, is associated with astrocytes, and marks the boundaries of areas in the developing rat brain (Geisert and Bidanset [1993] Dev. Brain Res., 75:163–173). In the present study TED15 was used to examine the distribution of ABAKAN during laminar development of the dorsal lateral geniculate nucleus in ferrets. This distribution was also compared with that of astrocytes as displayed with antibodies to GFAP. In the adult, TED15 and anti‐glial fibrillary acidic protein (GFAP) labeling are similar. Both are fairly uniform in the nucleus although somewhat elevated near the optic tract and in the interlaminar zone between laminae A and A1. During development the pattern is quite different. At postnatal day 1 (P1), before lamination is evident, TED15 and anti‐GFAP labeling are light in the nucleus. By P10, when laminae are emerging, both are elevated in the A‐A1 interlaminar zone and in the C laminae. At P18, when laminae are distinct, TED15 labels the A‐A1 interlaminar zone, and it marks the borders between the ON and OFF leaflets within A and A1 (Stryker and Zahs [1983] J. Neurosci. 3:1943–1951). In comparison, anti‐GFAP marks the interlaminar zone but not the ON/OFF leaflets. By 6 weeks the nucleus resembles the adult nucleus. These results show that ABAKAN marks the boundaries of the major functional subdivisions of the lateral geniculate nucleus in the developing ferret and suggest that it plays a role in lamination. © Wiley‐Liss, Inc.