bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chondroitin sulfate proteoglycans in the developing cerebral cortex: The distribution of neurocan distinguishes forming afferent and efferent axonal pathways
Authors: Miller Brad , Sheppard Allan M. , Bicknese Alma R. , Pearlman Alan L. 
Published: January 2005

AbstractThe first thalamocortical axons to arrive in the developing cerebral cortex traverse a pathway that is separate from the adjacent intracortical pathway for early efferents, suggesting that different molecular signals guide their growth. We previously demonstrated that the intracortical pathway for thalamic axons is centered on the subplate (Bicknese et al. [1994] J. Neurosci. 14:3500‐3510), which is rich in chondroitin sulfate proteoglycans (CSPGs; Sheppard et al. [1991] J. Neurosci. 11:3928‐3942), whereas efferent axons cross the subplate to exit in a zone containing much less CSPG. To define the molecular composition of the subplate further, we used antibodies against CSPG core proteins and chondroitin sulfate disaccharides in an immunohistochemical analysis of their distribution in the developing neocortex of the rat. Immunolabeling for neurocan, a central nervous system‐specific CSPG (Rauch et al. [1992] J. Biol. Chem. 267:19537‐19547), and for chondroitin 6‐sulfate and unsulfated chondroitin becomes prominent in the subplate before the arrival of thalamic afferents. Immunolabeling is initially sparse in the cortical plate but appears later in maturing cortical layers. A postnatal decline in immunolabeling occurs uniformly for most proteoglycans, but, in the somatosensory cortex, labeling for neurocan, phosphacan, and chondroitin 4‐ and 6‐sulfate declines in the centers of the whisker barrels before the walls. In contrast to neurocan, immunolabeling for other proteoglycans is either uniformly distributed (syndecan‐1, N‐syndecan, 5F3, phosphacan, chondroitin 4‐sulfate), restricted to axons (PGM1), distributed exclusively on nonneuronal elements (2D6, NG2, and CD44), or undetectable (9. 2. 27, aggrecan, decorin). Thus, neurocan is a candidate molecule for delineating the intracortical pathway of thalamocortical axons and distinguishing it from that of cortical efferents.
Morphological classification of retinal ganglion cells in mice
Authors: Doi Motoaki , Uji Yukitaka , Yamamura Hideki 
Published: January 2005

AbstractMice have been used for extensive studies on optic nerves and retinal ganglion cells, but mouse retinal ganglion cells have not been classified morphologically. In the present study, normally placed retinal ganglion cells and displaced retinal ganglion cells in pigmented and albino mice were classified morphologically using horseradish peroxidase. These cells were classified into three types according to the sizes of the soma and the dendritic field: type I cells, large soma and large dendritic field; type II cells, small‐to‐medium soma and small dendritic field; and type III cells, small‐to‐medium soma and large dendritic field. Some ganglion cells had both symmetric and asymmetric cells. Each type was further subdivided according to the termination level of dendrites in the inner plexiform layer and the dendritic branching pattern. Except for type III displaced ganglion cells, dendrites of the normally placed ganglion cells and the displaced ganglion cells ramify in the outer two‐fifths of the inner plexiform layer (sublamina a) or the inner three‐fifths of the inner plexiform layer (sublamina b). Type III displaced ganglion cells ramify only in sublamina a. Dendrites of some normally placed type I ganglion cells ramify in both sublaminae. Displaced biplexiform cells were observed, the dendrites of which ramify in both the inner and the outer plexiform layers. All cell types were found in both mouse strains. © 1995 Wiley‐Liss, Inc.
Fine structure of the dorsal latreral geniculate nucleus of the turtle, Emys orbicularis: A Golgi, combined hrp tracing and GABA immunocytochemical study
Authors: Kenigfest N. B. , Repérant J. , Rio J.‐P. , Belekhova M. G. , Tumanova N. L. , Ward R. , Vesselkin N. P. , Herbin M. , Chkeidze D. D. , Ozirskaya E. V. 
Published: January 2005

AbstractThe afferent and efferent cortical projections of the dorsal lateral geniculate nucleus (GLD) of adult specimens of the turtle Emys orbicularis were investigated after intraocular or intracortical injections of horseradish peroxidase (HRP), and the distribution of gamma aminobutyric acid (GABA) immunoreactivity in the nucleus was carried out by immunocytochemical techniques, both techniques being combined with light and electron microscopy. In addition, some specimens were prepared for double‐labeling of HRP and GABA immunoreactivity, and additional samples impregnated by a rapid Golgi technique. On purely morphological grounds, four types of neurons can be distinguished by light microscopy: two types of large cells in the cell plate which project to the cortex, and two types of smaller cells in the neuropil and optic tract which do not. The small cells are consistently GABA‐immunoreactive, while the former are, with extremely rare exceptions, immunonegative for GABA. The supposition that the small neurons of the neuropil are interneurons is supported by electron microscopic observations; these strongly GABA‐immunoreactive cells have large plicated nuclei surrounded by a thin layer of cytoplasm poorly endowed with organelles. The dendrites of these cells may contain pleomorphic synaptic vesicles (DCSVs) and appear to be presynaptic to other dendritic profiles. These DCSVs are occasionally contacted by GABA‐immunoreactive axon terminals, and more frequently by retinal terminals consistently immunonegative for GABA. The latter, frequently organized in glomeruli, also make synaptic contacts with immunonegative dendrites arising from corticopetal neurons of the cell plate. Two major categories of GABA‐immunoreactive axon terminals can be distinguished, and we are led to the conclusion that one of these represents an intrinsic GABAergic innervation of the GLD, while the second is tentatively interpreted as an extrinsic source of GABA to the nucleus, possibly from ventral thalamic structures. The fine structure of the dorsal lateral geniculate nucleus of Emys orbicularis thus shows many similarities with that of mammals. © 1995 Wiley‐Liss, Inc.
Chick wing innervation. I. Time course of innervation and early differentiation of the peripheral nerve pattern
Authors: Hollyday Margaret 
Published: January 2005

AbstractAnterograde transport of horseradish peroxidase was used to map the initial projection patterns of motor and sensory axons innervating the wing of the chick embryo. Injections which resulted in labeling large numbers of motor and sensory axons, separately or in combination, were used to define the time course of innervation and to visualize the progressive morphogenesis of the peripheral nerve pattern. Motor axons emerged from the spinal cord and accumulated near the ventromedial border of the myotome where they remained for up to 16 hours before growing into the plexus region and limb bud. Despite the known later time of sensory neuron production, the first sensory axons projected to the wing at the same time as motor axons. When axons first entered the wing bud, they were distributed in two loosely organized sheets of axon fascicles, one projecting to dorsal muscle mass, the other to ventral muscle mass. The width of the sheets was between one‐third to one‐half the width of the wing bud, and this distance was more than twice the diameter of the proximal nerve trunks measured at stage 28. In the proximal limb the basic pattern of peripheral nerves emerged gradually from stages 26 to 28. During these stages, the loosely organized sheets of axonal fascicles seen at younger stages were progressively transformed into several coherent nerve trunks and muscle nerves extended from common nerve trunks. The implication of these observations is that many outgrowing axons appear not to follow preformed pathways corresponding to the mature peripheral nerve branching pattern. This pattern may instead result from axonal recognition of cues within a largely undifferentiated limb bud, and from the subsequent bundling together of loosely organized axon fascicles. These events occur concurrently with limb growth and differentiation. © 1995 Wiley‐Liss, Inc.
Chick wing innervation. III. Formation of axon collaterals in developing peripheral nerves
Authors: Ferns Michael J. , Hollyday Margaret 
Published: January 2005

AbstractAxon navigation during vertebrate limb innervation has been shown to be associated with position‐dependent changes in size and complexity of the axon growth cones, and sometimes with bifurcation of terminal growth cones and axon branching (Hollyday and Morgan‐Carr, companion paper). We have further examined axon branching and asked whether it extends to the projection of collaterals to different nerves. Injections of horseradish peroxidase or DiI were made into individual peripheral nerves in the wings of chick embryos at stages 28–35, and the trajectories of solidly labeled axons were traced proximally from the injection site in tissue sections. During stages when the peripheral nerves were first forming in the shoulder region, collaterals of retrogradely labeled axons were frequently observed to project into uninjected nerves proximal to the injection site. These two‐nerve collaterals were formed by a small percentage of axons in a high percentage of the embryos studied and could occur in both motor and sensory axons. Two‐nerve collateral projections were observed between nerves separated along both the proximodistal and anteroposterior axes of the limb, but they were limited in spatial extent to nerves supplying adjacent limb regions and were never seen between nerves projecting to widely disparate regions of the limb. Collaterals were not seen at the plexus projecting to both dorsal and ventral pathways. The apparent frequency of two‐nerve collaterals was found to decline progressively from stage 28–29 to stage 32; no two‐nerve collaterals were seen in the proximal wing at stage 33 and older. The mechanism of their elimination is presently unknown. These observations suggest that some axon branching seen during outgrowth is sufficiently divergent to result in axon collaterals which project to two different peripheral nerves. Presumably, two‐nerve collaterals reflect both the neuron's ability to branch and some imprecision in the axonal guidance mechanisms. Together these give rise to minor errors in projection which are subsequently removed. © 1995 Wiley‐Liss, Inc.
Glutamate is concentrated in and released from parallel fiber terminals in the dorsal cochlear nucleus: A quantitative immunocytochemical analysis in guinea pig
Authors: Osen Kirsten K. , Storm‐Mathisen Jon , Ottersen Ole Petter , Dihle Beate 
Published: January 2005

AbstractThe present paper addresses the identity of the neurotransmitter(s) of the parallel fibers in the molecular layer of the dorsal cochlear nucleus, A brainstem center in the pathway for sound perception. The distribution of putative neurotransmitter amino acids was studied by using postembedding single‐ and double‐immunolabeling procedures. Perfusion‐fixed brains and immersion‐fixed slices from in vitro release experiments were evaluated. Quantitative immunogold analyses revealed that the parallel fiber terminals were significantly enriched with glutamate immunoreactivity compared with other terminals, dendrites, and glial processes. Within the parallel fiber terminals, the gold particles signaling the presence of glutamate were concentrated over vesicle clusters relative to the axoplasmic matrix. Furthermore, the parallel fiber terminals, but not the parent granule cell bodies, could be depleted of glutamate immunoreactivity by exposure to depolarizing concentrations of K+ in vitro. This depletion was partly dependent on Ca2+In double‐labeled preparations, the glutamine:glutamate ratio was by far higher in glial processes than in other types of profile. Aspartate immunoreactivity was mainly concentrated in neuronal cell bodies and dendrites and was very low in fiber terminals, particularly in those of the parallel fibers.These data indicate that parallel fiber terminals contain a glutamate pool that is associated with synaptic vesicles and that can be subject to release. The glial processes that are found in proximity to the terminals may provide them with the glutamine required for glutamate replenishment. No evidence was found for a neurotransmitter role of aspartate in the parallel fibers. © 1995 Wiley‐Liss, Inc.
Prenatal development of fibrous (white matter), protoplasmic (gray matter), and layer I astrocytes in the human cerebral cortex: A Golgi study
Authors: Marín‐padilla Miguel 
Published: January 2005

AbstractThe prenatal developmental histories of layer I, fibrous (white matter), and protoplasmic (gray matter) astrocytes have been studied in the human neocortex by the rapid Golgi method. The developmental route followed by each of these astrocytes is a distinct process which evolves from a specific precursor, occurs at a different time, and is linked to a specific event. The differentiation of layer I astrocytes is linked to the neocortex external glial limiting membrane (EGLM), that of fibrous astrocytes to the early white matter vascularization and maturation, and that of protoplasmic astrocytes to the late gray matter ascending vascularization and maturation. At the start of development, three glial precursors are established in the neocortex: 1) original radial neuroectodermal cells with nuclei above the primordial plexiform layer (PPL) by losing their ependymal and retaining their pial attachments become early astrocytes of layer I and EGLM components; 2) neuroectodermal cells with nuclei below the PPL that retain their pial and ependymal attachments become type I radial glial cells which are committed to the guidance of neurons and the early EGLM maintenance; and, 3) neuroectodermal cells that lose their pial but retain their ependymal attachment are transformed into type II radial glial precursors. By progressively losing their ependymal attachment, type II radial glia precursors become freely migrating cells, establish vascular contacts, and differentiate into fibrous astrocytes (and into oligodendrocytes?) throughout the subplate, developing white matter, and paraventricular regions. After the formation of the gray matter, additional layer I astrocytes are needed for the EGLM late prenatal and postnatal maintenance because type I radial glia cells start to regress and to reabsorb their EGLM endfeet. A late ependyma‐to‐pia migration of glial precursors progressively repopulates layer I with additional astrocytes and establishes the ephemeral subpial granular layer (SGL) of Ranke. From the 15th week of gestation to the time of birth, late astrocytes of layer I lose their EGLM attachments, migrate freely into the maturing gray matter, establish vascular contacts, and differentiate into protoplasmic astrocytes. The protoplasmic astrocytes of the gray matter evolve from transformation of layer I astrocytes rather than from radial glia cells as is generally believed. © 1995 Wiley‐Liss, Inc.
Brainstem afferents to the lateral mesencephalic tegmental region of the cat
Authors: Gerlach Irene , Thier Peter 
Published: January 2005

AbstractThe lateral mesencephalic tegmental region (LTR) is a part of the midbrain reticular formation characterized by the presence of neurons exhibiting head movement‐related discharge modulation. In addition, the LTR contains directionally selective visual units. Possible sources for these vestibular and visual signals were studied by retrograde axonal transport of horseradish peroxidase and three different fluorescent tracers (rhodamine, fast blue, and fluorogold) injected into various parts of the LTR.All injections into the LTR traced afferents from the vestibular nuclei and from the nucleus prepositus hypoglossi. Predominant projections were derived from the ipsilateral nucleus prepositus hypoglossi and the ipsilateral medial vestibular nucleus, whereas the observed inputs from the inferior, lateral, and superior vestibular nuclei were much weaker. Further inputs to the LTR originated in the deep and intermediate layers of the ipsilateral superior colliculus and the ipsilateral periaqueductal gray, the contralateral LTR, and the contralateral marginal nucleus of the brachium conjunctivum. Tracer deposits in medial parts of the tegmentum neighboring the LTR never produced the pattern of afferents observed after injections into the LTR.Our results suggest that afferents from the deeper layers of the superior colliculus are probably the source of visual signals in the LTR and that head movement‐related responses are likely to be derived from the nucleus prepositus hypoglossi and the medial vestibular nucleus. © 1995 Wiley‐Liss, Inc.
Laminar organization of receptive field properties in the dorsal lateral geniculate nucleus of the tree shrew (Tupaiaglis belangeri)
Authors: Holdefer Robert N. , Norton Thomas T. 
Published: January 2005

AbstractA laminar analysis of the receptive field properties of relay cells in the binocular region of the tree shrew dorsal lateral geniculate nucleus (LGN) found three main subdivisions. Lamina 1 (receiving ipsilateral eye input) and lamina 2 (contralateral) comprise a pair of layers that contain only ON‐center neurons. Laminae 4 (contralateral) and 5 (ipsilateral) comprise a pair of layers with mostly OFF‐center cells (86%). Laminae 3 and 6 (both contralaterally innervated) also form a distinct pair, although lamina 3 contains a mixture of cells with ON‐centers (43%) or OFF‐centers (57%), and lamina 6 contains mostly cells with ON‐OFF centers and suppressive surrounds (81%). Cells located in the interlaminar zones resembled neurons in laminae 3 and 6. In comparison with the cells in the OFF‐center laminae 4 and 5, the ON‐center cells in laminae 1 and 2 had smaller, more elliptical receptive field centers with stronger responses to flashed visual stimuli. In addition, cells in the ipsilateral eye laminae 1 and 5 showed a greater change in center diameter, with eccentricity from the area centralis, than cells in the contralateral eye laminae 2 and 4. Principal components analysis using six receptive field properties (latency to optic chiasm stimulation, receptive field center diameter, maintained discharge rate, response onset latency, peak spike density, and phasic‐tonic index) suggested that the cells in laminae 3 and 6 and the interlaminar zones are W‐like. Principal components analysis of the same receptive field properties in laminae 1, 2, 4, and 5 did not reveal differences clearly related to X‐like (parvocellular) and Y‐like (magnocellular) categories. Ninety‐seven percent of the cells tested for linearity of spatial summation in laminae 1, 2, 4, and 5 were linear. We conclude that the dominant organizational features of the tree shrew LGN are the ON‐center, OFF‐mter, and W pairs of layers that project to different regions within the striate cortex. © 1995 Wiley‐Liss, Inc.
Neurons of the median neuroblast lineage of the grasshopper: A population study of the efferent DUM neurons
Authors: Campbell Holly R. , Thompson Karen J. , Siegler Melody V. S. 
Published: January 2005

AbstractA group of lineally related neurons in the grasshopper was studied to determine the number of efferent neurons in the group and their morphological types. The neurons arise from the median neuroblast of the third thoracic neuromere and comprise what is commonly known as the DUM or dorsal unpaired median group. Of some 92 neurons in the group, about 20 are efferent neurons, the remainder being local or intersegmental interneurons. As part of our continuing developmental studies, we wished to identify the efferent neurons within the lineage and to determine their number. Ten efferent DUM neurons had been described in earlier studies, where neurons were stained individually through microelectrodes. The remaining unidentified neurons might be novel types, multiples of known types, or both, possibilities that would not be readily distinguished through further staining of neurons individually. Rather, we used methods of retrograde staining and axon tracing that allowed us to examine the entire group of efferent DUM neurons. Nineteen efferent neurons were identified, comprising two DUM1s, five DUM3s, six DUM3,4s, three DUM3,4,5s, and three DUM5s, neurons were named according to the lateral nerves containing their axons. The efferent neurons were further divided by type according to the distribution of axonal branches in lateral nerves, the course of the primary neurite within the deep or superficial DUM tract, and the diameter of the cell body. © 1995 Wiley‐Liss, Inc.
Hypothalamic Leu‐enkephalin‐immunoreactive fibers terminate on calbindin‐containing somatospiny cells in the lateral septal area of the rat
Authors: Szeidemann Zsolt , Shanabrough Marya , Leranth Csaba 
Published: January 2005

AbstractCorrelated light and electron microscopic double‐immunostaining experiments for Leuenkephalin and calbindin were employed to determine the postsynaptic targets in the septal complex of Leu‐enkephalin fibers. Chronic surgical isolation of the septal complex from its hypothalamic afferents and retrograde tracer studies using wheat germ agglutinin‐conjugated horseradish peroxidase, both followed by an immunostaining for Leu‐enkephalin, were performed to elucidate the location of the origin of these axon terminals. Furthermore, a colocalization study for glutamic acid decarboxylase and Leu‐enkephalin was carried out on hypothalamic sections to determine their possible coexistence in cells projecting to the lateral septum.These studies revealed that (1) Leu‐enkephalin‐immunoreactive axons form pericellular baskets around a population of lateral septal area neurons; (2) they establish exclusively asymmetric synaptic contacts on their soma and initial dendritic segments; (3) 10% of the lateral septal area calbindin‐contatining cells, which are all of the γ‐aminobutyric acid (GABA)‐ergic somatospiny type, are innervated by Leu‐erikephalin‐immunoreactive baskets; (4) only 40% of the Leu‐enkephalin target neurons are calbindin immunopositive; 5) the septopetal Leuenkephalin fibers derive from neurons located in the ipsilateral perifornical area and anterior hypothalamus; and 6) none of their cells of origin cocontains the inhibitory transmitter GABA. These observations indicate that hypothalamic Leu‐enkephalin‐containing neurons are nonGABAergic excitatory cells. Hence, they can effectively stimulate a population of lateral septal area neurons, including the somatospiny cells, which are all GABAergic. Therefore, after stimulatory Leu‐enkephalin action, these neurons can inhibit their postsynaptic targets, including other projective lateral septal neurons. © 1995 Wiley‐Liss, Inc.