bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dopaminergic and GABAergic cerebrospinal fluid‐contacting neurons along the central canal of the spinal cord of the eel and trout
Authors: Roberts B. L. , Maslam Suharti , Scholten G. , Smit W. 
Published: January 2005

AbstractIn anamniote vertebrates the central region of the spinal cord has been implicated in its regeneration. This is a complex region and so as a first step in understanding its possible regenerative role we have examined the organization of the cells that contact the lumen of the spinal cord in two teleost fishes, eel and trout, using immunohistochemical procedures and light and electron microscopy.Cell bodies immunoreacting positively with antibodies for tyrosine hydroxylase and for dopamine were located at the ventral rim of the central canal, whereas cell bodies reacting for an antibody for gamma‐aminobutyric acid were more laterally located. None of the canal‐contacting cells were positively immunoreactive for choline acetyltransferase. All immunopositive cells have a similar morphology: the amphora‐shaped perikaryon is bipolar and has a single process that extends to the lumen of the canal, and another that branches and forms extensive lateral and ventral plexuses. Electron microscopic investigations of the ventral dopaminergic cells showed that the apical processes bear one or more cilia, which protrude into the canal lumen and which originate from within a superficial rosette of nonciliated processes. The ventral process was occasionally seen to form synapses; the cell body was also the target of synapses. © 1995 Wiley‐Liss, Inc.
Development of A‐type (axonless) horizontal cells in the rabbit retina
Authors: Scheibe Ronald , Schnitzer Jutta , Röhrenbeck Jürgen , Wohlrab Frank , Reichenbach Andreas 
Published: January 2005

AbstractThe development of A‐type horizontal cells (HC) was studied in the rabbit retina between embryonic day (E)24 and adulthood [the day of birth was called postnatal day (P)1 and corresponds to E31–32]. The cells were visualized by several methods 1) by immunolabeling with antibodies to neurofilament 70000 (NF‐70kD), 2) by immunolabeling with antibodies to a calcium binding protein (CaBP‐28kD), 3) by two different methods of silver impregnation, and (4) by histochemical demonstration of NADH‐diaphorase activity. Most methods labeled A‐type HC only in the dorsal retina; thus, our study is restricted to HC of this region. HC densities were determined at each developmental stage. The cells were drawn at scale, and size, quotient of symmetry, and topographical orientation of dendritic trees were studied by image analysis. The growth of HC dendritic fields was correlated with data on the postnatal local retinal expansion, which is known to be driven by the intraocular pressure (after cessation of retinal cell proliferation at P9). This expansion was evaluated in an earlier paper (Reichenbach et al. [1993] Vis. Neurosci. 10:479–498) by using local subpopulations of Müller cells as “markers” of distinct topographic regions of the retinae. After E24, when the final number of HC is established, we can discriminate three distinct developmental stages of A‐type HC. During the first stage, between E24 and E27, the young cells are often vertically oriented and may extend their first short dendrites within (the primordia of) both plexiform layers. The irregular HC mosaic at E24 shows a significant difference to all other stages. The second stage begins after birth when the dendritic trees of the cells are already restricted to the outer plexiform layer. Between P3 and P9, their dendritic trees enlarge more than the surrounding retinal tissue expands, and the coverage factor almost doubles from 2.5 to 4.4. The third stage occurs after P9 when the growth rate of dendritic tree areas corresponds to that of the local retinal tissue expansion caused by “passive stretching” of the postmitotic tissue, and the coverage factor remains constant. This is compatible with the view that mature synaptic connections of A‐type HC are mostly established after the first week of life and are then maintained. © 1995 Wiley‐Liss, Inc.
Neurotransmitter modulation of Fos‐ and Jun‐like proteins in the turtle retina
Authors: Yaqub Asma , Guimaraes Marilia , Eldred William D. 
Published: January 2005

AbstractThe expression of the Fos and Jun families of nuclear phosphoproteins can be induced by a variety of extracellular stimuli and is known to participate in the transcriptional regulation of target genes. To examine the role of these transcription factors in retinal function, we used polyclonal antisera to localize these protein families in the turtle retina. Fos‐like immunoreactivity was in many somata in the inner nuclear and ganglion cell layers. In contrast, Jun‐like immunoreactivity was in a smaller number of amacrine cells and many somata in the ganglion cell layer. The monostratified dendritic arbors of one prominent amacrine cell type with Jun‐like immunoreactivity were also labeled. There were no dramatic differences in the levels of Fos‐like immunoreactivity or Jun‐like immunoreactivity between light‐ or dark‐adapted retinas.We examined the effects of excitatory amino acids and γ‐aminobutyric acid (GABA) on the expression of these proteins in vitro. In some experiments, cobalt was used to block synaptic transmission. The excitatory amino acids increased both Fos‐ and Jun‐like immunoreactivity, while GABA generally showed no such stimulatory effect. In cobalt‐treated retinas, the same cell types had Jun‐like immunoreactivity as seen in the controls, but overall levels of immunoreactivity were increased. In cobalt‐treated dark‐adapted retinas, some excitatory amino acids increased cytoplasmic Fos‐like immunoreactivity in the somata and processes of large cells in the ganglion cell layer. Our results suggest that Fos‐ and Jun‐related proteins may play an important role in the postsynaptic responses to amino acid transmitters in a wide variety of amacrine and ganglion cells. © 1995 Wiley‐Liss, Inc.
Morphology of physiologically identified retinal X and Y axons in the cat's thalamus and midbrain as revealed by intraaxonal injection of biocytin
Authors: Tamamaki Nobuaki , Uhlrich Daniel J. , Sherman S. Murray 
Published: January 2005

AbstractPrior morphological studies of individual retinal X and Y axon arbors based on intraaxonal labeling with horseradish peroxidase have been limited by restricted diffusion or transport of the label. We used biocytin instead as the intraaxonal label, and this completely delineated each of our six X and 14 Y axons, including both thalamic and midbrain arbors. Arbors in the lateral geniculate nucleus appeared generally as has been well documented previously. Interestingly, all of the labeled axons projected a branch beyond thalamus to the midbrain. Each X axon formed a terminal arbor in the pretectum, but none continued to the superior colliculus. In contrast, 11 of 14 Y axons innervated both the pretectum and the superior colliculus, one innervated only the pretectum, and two innervated only the superior colliculus. Two of the Y axons were quite unusual in that their receptive fields were located well into the hemifield ipsilateral with respect to the hemisphere into which they were injected. These axons exhibited remarkable arbors in the lateral geniculate nucleus, diffusely innervating the C‐laminae and medial interlaminar nucleus, but, unlike all other X and Y arbors, they did not innervate the A‐laminae at all. In addition to these qualitative observations, we analyzed a number of quantitative features of these axons in terms of numbers and distributions of terminal boutons. We found that Y arbors contained more boutons than did X arbors in both thalamus and midbrain. Also, for axons with receptive fields in the contralateral hemifield (all X and all but two Y axons), 90–95% of their boutons terminated in the lateral geniculate nucleus; the other two Y axons had more of their arbors located in midbrain. © 1995 Wiley‐Liss, Inc.
Electron microscopy of cell islands in layer II of the primate entorhinal cortex
Authors: Goldenberg Todd M. , Bakay Roy A. E. , Ribak Charles E. 
Published: January 2005

AbstractAn electron microscopic analysis of cell islands in layer II of the entorhinal cortex from rhesus monkeys was made to determine the ultrastructural features of these unique neuronal clusters. The rostral, intermediate, and caudal divisions of the entorhinal cortex were selected for electron microscopic examination. In the rostral division, neurons were grouped together in prominent clusters, often with 10 or more contiguous somata. Somatic and dendrosomatic appositions were frequent, without intervening cellular processes or specialized junctions. Somata were relatively small, typically 10–15 μm in diameter, with oval or circular nuclei that were euchromatic and contained nucleoli. Small nuclear infoldings were commonly seen. A thin shell of perikaryal cytoplasm contained numerous organelles. Axosomatic synapses were infrequent, with a mean of only 1. 0 synapse per neuron per thin section. The neuropil contained numerous synapses, and myelinated axons were seen infrequently. In the intermediate division, somatic appositions were rarely observed. Somata were relatively large, typically 15–20 μm in diameter, and displayed a moderate amount of cytoplasm. Axosomatic synapses were relatively common, with a mean of 3. 3 synapses per neuron per thin section. In the caudal division, neurons were typically grouped in clusters of two to three contiguous somata. Neurons were about 15 μm in diameter and displayed a moderate amount of cytoplasm. Axosomatic synapses were of moderate frequency, with a mean of 2. 5 synapses per neuron per thin section. The neuropil in the caudal division displayed a relatively high frequency of myelinated axons.Our analysis of three regions of the entorhinal cortex revealed significant differences in the frequency of somatic appositions and axosomatic synapses, and in certain ultrastructural features of the somata and neuropil. These results showed that cell islands in layer II of the entorhinal cortex display regional morphologic differences. The paucity of symmetric axosomatic synapses in the rostral division may correlate with this region's vulnerability in certain diseases.
Oligodendrocytes in female carriers of the jimpy gene make more myelin than normal oligodendrocytes
Authors: Skoff Robert P. , Said Ghandour M. 
Published: January 2005

AbstractThe female carrier of the jimpy (jp) gene is a model system to study the plasticity of neuroglial cells and the mechanisms they use to compensate for a temporary deficit in myelin. Myelin in the female carriers is reduced 30‐40% during the first postnatal month but is normal in adults. We hypothesized that the number of oligodendrocytes (OLs) in the female carriers is increased, based upon previous data showing OL proliferation is increased but the number of dying OLs is only slightly elevated in development. To test this hypothesis, antibodies to carbonic anhydrase (CA)II, an OL‐specific marker, were used to quantify the number of OLs in the spinal cords of 1‐month‐old and adult female carriers. Contrary to expectations, the number of OLs is significantly reduced in the dorsal funiculus and grey matter by 21% in adult female carriers compared to controls. A reduction of lesser magnitude is present in the 1‐month‐old animals. Electron microscopic montages prepared from normal and carrier dorsal funiculus we used to count total numbers of glia. Ultrastructural quantification shows a similar reduction in the number of OLs and confirms the validity of the CAII immunostaining as a means to quantify OLs.These data show that there are 21% fewer OLs in the central nervous system (CNS) of adult female carriers but normal amounts of myelin. Presumably, some OLs in the carrier CNS are maintaining more myelin than their counterparts in normal CNS would. These findings demonstrate that (1) a reduction in number of OLs does not necessarily involve a reduction in the amount of myelin, and (2) OLs have considerable flexibility in the amount of myelin they can make.
Ultrastructural examination of the targets of serotoninn immunoreactive descending interneurons in the guinea pig small intestine
Authors: Young H. M. , Furness J. B. 
Published: January 2005

AbstractSerotonin neurons are descending interneurons in the myenteric plexus of the guinea pig small intestine. Preembedding single‐ and double‐label immunocytochemistries at the ultrastructural level were used to identify the targets of these serotonin interneurons.Serial ultrathin sections were taken through a myenteric ganglion that had been processed for serotonin immunocytochemistry. The ganglion contained the cell bodies of 69 neurons, including 2 serotonin neurons and 6 neurons with the ultrastructural features of Dogiel type II cells. For each cell body in the ganglion, the number of serotonin inputs (synapses and close contacts) was determined. About 50% of the cell bodies did not receive any serotonin inputs. The most abundant serotonin terminals were related to two targets: other serotonin descending interneurons and a population of neurons with Dogiel type I morphology, but whose neurochemistry and function is unknown. The serotonin inputs to the serotonin cell bodies were located predominantly on the lamellar dendrites. Each of the Dogiel type II neurons received 3 or fewer serotonin inputs, and none of the serotonin inputs to Dogiel type II neurons formed a synapse. Overall, about 40% of the serotonin inputs formed synapses. The serotonin inputs to neurons that received many serotonin inputs were more likely to show synaptic specializations than serotonin inputs to neurons that received few serotonin inputs.Inhibitory motor neurons contain nitric oxide synthase (NOS). At the light microscope level, serotonin nerve fibers do not form dense pericellular baskets around NOS cell bodies. To determine whether there are serotonin input to NOS neurons, serial ultrathin sections were taken through a myenteric ganglion that had been processed for preembedding double‐label immunocytochemistry, in which the NOS neurons were labeled with peroxidase‐diaminobenzidine and the serotonin neurons with silver‐intensified 1 nm gold. Only 1 out of 9 NOS cells examined in serial section received more than 5 serotonin inputs. The results suggest that, in the guinea pig small intestine, the serotonin descending interneurons are not an essential element of the descending inhibitory reflex. © 1995 Wiley‐Liss, Inc.
Thalamocortical synapses between axons from the mediodorsal thalamic nucleus and pyramidal cells in the prelimbic cortex of the rat
Authors: Kuroda Masaru , Murakami Kunio , Kishi Kiyoshi , Price Joseph L. 
Published: January 2005

AbstractA combined anterograde axonal degeneration and Golgi electron microscopic (Golgi‐EM) study was undertaken to identify thalamocortical synaptic connections between axon terminals from the mediodorsal thalamic nucleus (MD) and pyramidal cells in layers III and V of the agranular prelimbic cortex in the rat. The morphological characteristics of thalamocortical synapses from MD were also examined by labeling axon terminals with anterograde transport of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP).WGA‐HRP labeled axon terminals from MD to the prelimbic cortex were small in size (0.5–1 μm in diameter), contained round synaptic vesicles, and formed axospinous synapses with asymmetrical membrane thickenings. With Golgi‐EM methods, gold‐toned apical dendrites in layer III were analyzed by reconstruction of serial ultrathin sections. Following lesions in the thalamus, degenerating thalamocortical axon terminals formed asymmetrical contacts exclusively on dendritic spines of the identified apical dendrites. More thalamocortical synapses were found on apical dendrites of layer V pyramidal cells than on apical dendrites of layer III pyramidal cells. In addition to thalamocortical synapses, a very few unlabeled symmetrical synapses were found on apical dendrites and somata of pyramidal cells, but they were not quantified and their sources are unknown. © Wiley‐Liss, Inc.
Expression of neurofilament proteins during development of the nervous system in the squid Loligo pealei
Authors: Grant Philip , Tseng Daniel , Gould Robert M. , Gainer Harold , Pant Harish C. 
Published: January 2005

AbstractThe squid nervous system includes various brain ganglia, optic lobes (the visual center), and the stellate ganglia, the system of giant motor fibers responsible for rapid jet‐propelled escape behavior. The large caliber of giant fibers is due, in part, to the accumulation of squid‐specific neurofilaments (NFs) made up of a heavily phosphorylated NF 220 protein together with NF 70 and NF 60 subunits. Using antibodies prepared against known peptide sequences in these proteins, together with a mammalian‐derived antibody that specifically recognizes phosphorylated squid NF 220, we studied the localization of NFs in adult tissues and during neural development. Immunoblot and immunohistochemical analyses showed that NFs were present in adult neural tissues, primarily in selected fibers, with giant axons showing the most robust expression. After the first neurons differentiated at stage 22, immunoblots showed NF 60– and NF 70–immunoreactive proteins at all stages. The NF 220 subunit, however, was not detected in immunoblots at any developmental stage. Phosphorylated NF 220 immunoreactivity, although absent in immunoblots, was first seen in selected fibers of the stellate ganglia at stage 25, increasing thereafter in all giant fibers until hatching (stage 30). The stellate ganglion is the first neural tissue to acquire a mature neurofilament complement (i. e., phosphorylated NF 220), shortly before the onset of jet‐propelled escape behavior. The temporal pattern of expression of the NFs during development resembled that seen in vertebrates; i. e., the smaller NFs appeared before the larger subunit in most neural tissues. In the squid, the expression pattern seems to depend upon the post‐transcriptional regulation of a single gene rather than upon transcriptional regulation of three independent genes as in vertebrates. © 1995 Wiley‐Liss, Inc.
Circuit reorganization in granuloprival cerebellar cultures in the absence of neuronal activity
Authors: Seil Fredrick J. , Drake‐Baumann Rosemarie 
Published: January 2005

AbstractNeonatal mouse cerebellar cultures exposed to cytosine arabinoside for the first 5 days in vitro to destroy granule cells and compromise glia undergo a circuit reorganization featured by profuse sprouting of Purkinje cell recurrent axon collaterals, which hyperinnervate the somata of other Purkinje cells and project to Purkir& cell dendritic spines. Such granuloprival cultures were exposed continuously from explanation to tetrodotoxin and elevated levels of magnesium to block neuronal activity. A similar circuit reorganization occurred, except that there was a reduction in the number of axospinous synapses and Purkinje cell axosomatic synapses, which in this case were all inhibitory. Functionally, after recovery from the blockade, granuloprival cultures developed sustained cortical hyperactivity, which was consistent with the reduction of inhibitory synapses. While the absence of neuronal activity did not prevent reorganizational changes following granule cell loss, the full development of the inhibitory circuitry was not attained. These results further support the concept that spontaneous neuronal activity is necessary for the complete development of inhibitory synapses. © 1995 Wiley‐Liss, Inc.
Morphology and kainate‐receptor immunoreactivity of identified neurons within the entorhinal cortex projecting to superior temporal sulcus in the cynomolgus monkey
Authors: Good Paul F. , Morrison John H. 
Published: January 2005

AbstractProjections of the entorhinal cortex to the hippocampus are well known from the classical studies of Cajal (Ramon y Cajal, 1904) and Lorente de Nö (1933). Projections from the entorhinal cortex to neocortical areas are less well understood. Such connectivity is likely to underlie the consolidation of long‐term declarative memory in neocortical sites. In the present study, a projection arising in layer V of the entorhinal cortex and terminating in a polymodal association area of the superior temporal gyrus has been identified with the use of retrograde tracing. The dendritic arbors of neurons giving rise to this projection were further investigated by cell filling and confocal microscopy with computer reconstruction. This analysis demonstrated that the dendritic arbor of identified projection neurons was largely confined to layer V, with the exception of a solitary, simple apical dendrite occasionally ascending to superficial laminae but often confined to the lamina dissecans (layer IV). Finally, immunoreactivity for glutamate‐receptor subunit proteins GluR 5/6/7 of the dendritic arbor of identified entorhinal projection neurons was examined. The solitary apical dendrite of identified entorhinal projection neurons was prominently immunolabeled for GluR 5/6/7, as was the dendritic arbor of basilar dendrites of these neurons. The restriction of the large bulk of the dendritic arbor of identified entorhinal projection neurons to layer V implies that these neurons are likely to be heavily influenced by hippocampal output arriving in the deep layers of the entorhinal cortex. Immunoreactivity for GluR 5/6/7 throughout the dendritic arbor of such neurons indicates that this class of glutamate receptor is in a position to play a prominent role in mediating excitatory neurotransmission within hippocampal‐entorhinal circuits. © 1995 Wiley‐Liss, Inc.
Requirement of RNA synthesis for pathfinding by growing axons
Authors: Von Bernhardi R. , Bastiani M. J. 
Published: January 2005

AbstractThe effects of actinomycin D were studied in cultured grasshopper embryos at different stages of development by following the outgrowth patterns of identified neurones known as aCC, pCC, and Q1. When administered at stages occurring before 31% of embryonic development, actinomycin D (0.05‐0.10 μM for 24‐48 hours) prevented axon extension, whereas it did not affect the development of the nervous system in embryos older than 34% of development. At 31‐‐34% of development, actinomycin D perturbed pathfinding of aCC without blocking axon extension. Thus, only 22% of the aCCs (n=271) in embryos treated with actinomycin D extended an axon along the intersegmental nerve as in control embryos. In the remaining embryos, aCC failed to turn into the intersegmental nerve root; its growth cone remained in the longitudinal connective, above or below the turning point. Neurones of the group caudal to the intersegmental nerve root could extend along either the anterior or posterior commissure of the next posterior segment.In contrast to the observations made with aCC, only 1.2% of pCC (n=166) and 0.0% of Q1 (n=45) in embryos treated with actinomycin D showed axon growth along aberrant pathways. The position of the growth cones of most pCCs and all Q1s observed were in various points along their normal pathway. Both pCC and Q1, as a population, showed an extension rate significantly lower than that of their control counterparts.The effect of actinomycin D on aCC pathway choice was probably mediated by inhibition of RNA synthesis, because incorporation of uridine into RNA was reduced by 40%. The labelling of several monoclonal antibodies (1C10, 3B11, 7F7) that recognise surface glycoproteins (lachesin, fasciclin I, and REGA‐1) involved in nervous system development of grasshopper embryos was suppressed. Our results suggest that the navigation of some axons along different pathways requires the synthesis of new mRNA. © 1995 Wiley‐Liss, Inc.