bluuebunny/crossref_metadata_2025_split huggingface dataset:
Granule cells in the rat olfactory tubercle accumulate 3H‐γ‐aminobutyric acid
Authors: Krieger Neil R. , Megill John R. , Sterling Peter 
Published: May 2005

AbstractThe rat olfactory tubercle contains high concentrations of γ‐aminobu‐tyric acid (GABA) and its synthetic enzyme, glutamic acid decarboxylase (GAD). We previously demonstrated that GABA and GAD are most concen‐trated in the polymorphic layer of the tubercle and relatively absent from the plexiform and pyramidal layers. Here we report that the granule cells (the islands of Calleja) in the polymorphic layer.accumulate 3H‐GABA.3H‐GABA Ci/mmole; 1.5 μ1 was injected trie tubercle and an hour later the rat was perfused with a mixture of paraformaldehyde and glu‐taraldehyde. The tissue was osmicated, dehydrated, and embedded in epon. Silver grains were sparse over the pyramidal and polymorphic cell bodies but numerous over the granule cell bodies in the islands of Callejaanddendrites in the surrounding.neuropjl. Grain densities for the granule cells were 41/100 μm3 compared to 4.2 for pyramidal and polymorphic cells. Witnm the island, all the granule cells appeared to be labeled. These results, com‐bined with previous demonstrations of the presence in this region of endo‐genous GABA and GAD, suggest that the granule neurons of the rat olfac‐tory tubercle are GABA‐ergic. These neurons also appear to receive dopamine input and therefore form part of a circuit that includes targets for both major and minor tranquilizers.
Commissural inhibition and facilitation of granule cell discharge in fascia dentata
Authors: Douglas R. M. , McNaughton B. L. , Goddard G. V. 
Published: May 2005

AbstractStimulation of the contralateral hippocampus in the hilar region had a marked effect on granule cell excitability in the fascia dentata. The primary effect was to block the population spike that otherwise occurred in response to perforant path stimulation. In contrast, the size of the excitatory post‐synaptic potential component of the perforant path‐evoked field potential was only slightly reduced. The population spike diminution began at short latency (3.5 msec), beginning at about 1.0 msec after the onset of the slow component of the potential evoked by the contralateral stimulus. The completeness and duration of this population spike diminution depended on the contralateral stimulus intensity. The maximum duration was less than 40 msec in unanesthetized rats and more than 100 msec in rats under pento‐barbital anaesthesia. Bicuculline did not diminish the field potential evoked bythe contralateral stimulus but it did prevent the stimulus from blocking the perforant path population spike and, instead, permitted a weak facilitation of the population spike. The normal reduction of the population spike was not mediated by recurrent inhibition, secondary to granule cell activation, since it occurred whether or not the granule cells were inhibited at the time of contralateral stimulation. These results imply that the initial main effect on fascia dentata granule cells of activity in the contralateral hilus is a γ‐aminobutyric‐acid‐mediated inhibition. This effect most probably involves commissural excitation of local inhibitory interneurons. The direct excitatory action of commissural fibers on granule cells, by comparison, is very weak.
Lectin cytochemistry and freeze‐fracture study of phagocytosis in the rat retina
Authors: McLaughlin Barbara J. , Boykins Lou G. 
Published: May 2005

AbstractLectin cytochemistry and freeze‐fracture intramembrane morphology have been studied in adult rat retinas during various stages of the phagocytic cycle. Animals were perfused with aldehydes at various times during the first 6 hours of light and the retinas were removed. Chopped sections of tissue were stained with one of two lectin‐peroxidase conjugates: ricinis communis agglutinin (RCA), which is specific for n‐acetylgalactosamine and galactose, or wheat germ agglutinin (WGA), which is specific for n‐acetylglucosamine and sialic acid. Other sections were frozen and prepared for freeze fracture.During the first hour of light onset, numerous phagosomes are already present in the retinal pigment epithelial (RPE) cytoplasm. The engulfment stages of phagocytosis whereby the RPE microvilli wrap around and enclose shed rod outer segment (ROS) tips are rarely observed at this time. Newly formed phagosomes are present in the apical RPE cytoplasm while older and more osmiophilic phagosomes are located deeper within the RPE cytoplasm. Between 2 and 4 hours of light onset fewer phagosomes are present in the RPE cytoplasm, but it is common to observe many ROS tips in various stages of microvillous engulfment. By 6 hours phagosomes are rarely present but some engulfed ROS tips continue to be observed. Both RCA and WGA stain RPE microvilli and plasma membranes of photoreceptor outer segments. WGA, in addition, labels some intradisc membranes of intact and also shed outer segments that are being engulfed but does not label disc membranes in phagosomes. At all times, phagosomes are rimmed by both lectin stains, but their internal contents are never stained. Lysosomes and multivesicular and residual bodies are labeled by both lectins. Freeze‐fractured retinas show that as the ROS tips are engulfed, particle‐free areas are present on disc P‐face (cytoplasmic) membranes. Many newly formed phagosomes also display particle‐free membrane areas and older phagosome membranes are completely devoid of particles. These observations show that the changes in WGA staining and intramembrane particle distribution on disc membranes occur in retinas during phagocytosis and suggest that some membrane component that is present for the initial phagocytic interaction may be rapidly degraded thereafter.
Myelin breakdown and elimination in the posterior funiculus of the adult cat after dorsal rhizotomy: A light and electron microscopic qualitative and quantitative study
Authors: Franson Peter , Ronnevi Lars‐Olof 
Published: May 2005

AbstractAdult cats were subjected to unilateral dorsal L6, L7, and S1 rhizotomy. After survival times of 1‐1,552 days the degeneration of axons and myelin sheaths and the elimination of degenerating myelin was studied qualitatively and quantitatively with light and electron microscopy and in Marchi‐stained sections in the posterior funiculus in T12‐L2.Degeneration was first observed as swollen or shrunken nerve fibers. Somewhat later there was an increased occurrence of collapsed myelin sheaths. The latter lost their myelin periods and appeared to be transformed into myelin bodies. The occurrence of myelin bodies coincided temporally with the presence of many Marchi‐positive bodies. Later, an increasing number of intracellularly located lipid droplets occurred, paralleled by the occurrence of a great number of Marchi‐positive granules and crystalline structures.Profiles of collapsed myelin sheaths, myelin bodies, and lipid droplets were frequently seen in the cytoplasm of microglial cells. Later, astrocytes and perivascular cells became filled with numerous lipid droplets.The findings suggest that microglial cells take up collapsed myelin sheaths and within these cells the sheaths become transformed into myelin bodies and subsequently into lipid droplets. These two products of myelin disintegration appear to correspond to the Marchi‐positive structures seen during the degeneration process. The lipid droplets appear to be transported to astrocytes and perivascular cells.
Synaptic contacts between bipolar and photoreceptor cells in the retina of Callionymus lyra L.
Authors: Van Haesendonck E. , Missotten L. 
Published: May 2005

AbstractA combined light and electron microscopic study of Golgi‐impregnated retinas of the marine teleost Callionymus lyra L. revealed mixed bipolar cells (M types) contacting rods and cones and pure cone bipolar cells (C types). Five types of mixed bipolar cells can be differentiated on the basis of their synaptic contacts. Two out of the five mixed bipolar cell types contact double cones, single cones, and rods (mixed, dark, pale, single [Mdps and midget‐Mdps]). Their endbuds make narrow cleft junctions, with each type of photoreceptor, and in addition, two endbuds end centrally in the synaptic ribbon complexes of the dark and pale double‐cone pedicles. Three types of mixed bipolar cells contact only double cones and rods. The endbuds of one type (mixed, dark, pale, ribbon [Mdpr]) end centrally in the synaptic ribbon complexes of the dark and pale double‐cone pedicles as well as of the rod spherules. The endbuds of two types (Mdp and midget‐Mdp) make wide cleft junctions in dark and pale double‐cone pedicles and in rod spherules. All pure cone bipolar cell types contact cones exclusively with narrow cleft junctions. Four types are seen: a type that contacts predominantly pale double‐cone pedicles but also a few dark double‐cone pedicles (Cp), a type that is connected with dark and pale double‐cone pedicles in about equal numbers (Cdp), a type that makes synaptic contacts with pale double‐cone pedicles and single‐cone pedicles (Cps), and a type that is connected with both types of double cones and to single‐cone pedicles (Cdps). A resemblance between the ultrastructural features of mixed bipolar cell synapses in Callionymus and in Carassius auratus is noted.
Some observations on the course and composition of the cingulum bundle in the rhesus monkey
Authors: Mufson Elliott J. , Pandya Deepak N. 
Published: May 2005

AbstractThe course and composition of the cingulum bundle was examined by using the autoradiographic tracer technique in the rhesus monkey. The cingulum bundle is observed to consist of three major fiber components originating from thalamus, cingulate gyrus, and cortical association areas. Following isotope injections in the anterior and lateral dorsal thalamic nuclei, labelled fibers form an arch in the white matter behind the cingulate sulcus and occupy the ventral sector of the cingulum bundle. The fibers from the anterior thalamic nucleus coursing in the cingulum bundle extended rostrally to the frontal cortex and caudally to area 23 and the retrosplenial cortex. In contrast, the fibers from lateral dorsal nucleus reached the retrosplenial cortex as well as the parahippocampal gyrus and presubiculum. Efferent fibers from the cingulate gyrus occupy a dorsolateral sector of the cingulum bundle. Those fibers from area 24 of the cingulate gyrus are directed to the premotor and prefrontal regions as well as area 23 and retrosplenial cortex. The fibers from area 23 extend rostrally to the prefrontal cortex and caudoventrally to the presubiculum and parahippocampal gyrus. Finally, an association component originates mainly from prefrontal cortex and posterior parietal region. These fibers occupy a more dorsal and lateral periphery in the cingulate white matter. Cingulum bundle fibers from the prefrontal cortex extend up to the retrosplenial cortex while those from the posterior parietal cortex extend caudally to the parahippocampal gyrus and presubiculum, and rostrally up to the prefrontal cortex.
Electron microscopic and immunohistochemical evidence that unmyelinated ventral root axons make U‐turns or enter the spinal pia mater
Authors: Risling M. , Dalsgaard C.‐J. , Cukierman A. , Cuello A. C. 
Published: May 2005

AbstractThe occurrence of unmyelinated and small myelinated axons and of nerve fibres with a substance P‐like immunoreactivity was studied in juxtamedullary L7 ventral root fascicles and surrounding pia mater of kittens and cats. Electron microscopic analysis of thin transverse serial sections from this region in adult cats showed that the number of unmyelinated axon profiles decreases rapidly as the CNS is approached, reaching zero near or at the CNS/PNS border. No unmyelinated axons were found to enter the CNS through this root. At least to some extent, the disappearance of unmyelinated ventral root axons from the juxtamedullary root fascicles was due to presence of intrafascicular axonal hairpin loops and to a shift of axons from ventral root fascicles to the pia mater. It was also found that, as in the L7 ventral root, the content of unmyelinated axons in the pia mater is lower in kittens than in cats. Fluorescence microscopic examination of specimens incubated with substance P antiserum showed that some looping axons and ventral root‐pia mater axons were substance P immunoreactive. These observations suggest the hypothesis that sensory unmyelinated axons might grow through the L7 ventral root and enter the pia mater during postnatal development. Moreover they show that the occurrence of sensory unmyelinated axons in ventral roots does not necessarily contradict the law of Magendie.
Immunocytochemical localization of a methionine‐enkephalin‐resembling neuropeptide in the central nervous system of the american cockroach, Periplaneta americana L
Authors: Verhaert Peter , de Loof Arnold 
Published: May 2005

AbstractUsing the peroxidase antiperoxidase immunocytochemical method, we were able to demonstrate within the brain and retrocerebral complex of Periplaneta americana several neuronal structures which were very specifically stained with an anti‐methionine‐enkephalin antiserum. From the precise localization of this immunoreactive material some speculations about its possible functions could be derived, such as a neurotransmitter‐ or neuromodulatorlike function and/or a neurohormonal role. These data present new evidence for the recently developed concept that opiate peptides, identical or related to those found in higher species, occur also in invertebrates.
Cholinergic amacrine cells in the rat retina
Authors: Voigt Thomas 
Published: May 2005

AbstractStaining of rat retinal wholemounts with a monoclonal antibody against choline‐acetyl‐transferase (ChAT) reveals two matching populations of amacrine cells in pigmented and albino rat retinae. One population has cell bodies in the inner nuclear layer (INL). Their dendrites are confined to a narrow stratum in the outer half of the inner plexiform layer (IPL). The other, displaced, population has cell bodies in the ganglion cell layer (GCL) withdendrites stratifying in the middle of the IPL. The density changes with eccentricity, ranging from 1,700 cells/mm2 centrally to 600 cells/mm2 in the periphery. Presumptive cholinergic cells were filled withthe fluorescent dye Lucifer yellow. Both subpopulations have the same “starburstlike” morphology as described for rabbit cholinergic amacrine cells (Famiglietti, '83; Tauchi and Masland, '84; Masland et al., '84b). Their dendritic tree sizes change with eccentricity andrange from 160 to 300 μm in diameter. Counterstaining of Lucifer yellow‐filled cells by ChAT immunohistochemistry did not yield an unequivocal double staining. Nevertheless, indirect evidence of same soma size, same numberand form of primary dendrites, same level of stratification, and the good fit into the cholinergic mosaic makes it very likely that the “starburstlike” amacrine cells in the rat use acetylcholine as their transmitter. A comparison with the rabbit cholinergic system strengthens this assumption and reveals a striking similarity between both species.
Neuropeptide‐Like immunoreactive cells in the retina of the larval tiger salamander: Attention to the symmetry of dendritic projections
Authors: Yang Chen‐Yu , Yazulla Stephen 
Published: May 2005

AbstractLight microscopic immunocytochemistry was used to study the morphology of cells that showed immunoreactivity (IR) to antisera against substance P (SP), glucagon (GLU), met enkephalin (ENK), and somatostatin (SS) in the retina of the larval tiger salamander. Both vertical sections and retinal whole mounts were studied. All four antisera labeled amacrine cells in the inner nuclear layer and cells in the ganglion cell layer (GCL). GLUIR cells had processes stratified throughout the inner plexiform layer (IPL), whereas the other three types had bistratified projections in laminae 1 and 5, withlamina 5 being broader and more dense. Two types of SS‐IR amacrine cell were observed. As seen in retinal whole mount, most GLU‐IR and ENKIR amacrine cells had processes that were symmetrically distributed about the soma, whereas processes of SS‐ and SP‐IR amacrine cells were markedly asymmetrical. The dendritic fields of SP‐IR amacrine cells were selectively oriented toward the periphery of the retina in the nasal, temporal, and dorsal areas. Immunoreactive cells in the GCL had fine projections into the IPL and in addition gave rise to two large oriented processes proximal to the soma that projected in opposite directions for 100–200 μm. The oriented processes often showed further branching; they appeared to be along the radiated lines from the optic disc but did not enter it. The implications of the selectively oriented processes of SP‐IR amacrine cells and cells in the GCL are discussed.
A combined 2‐deoxyglucose and neurophysiological study of primate somatosensory cortex
Authors: Juliano Sharon L. , Whitsel Barry L. 
Published: May 2005

AbstractThe metabolic activity pattern produced in the primary somatosensory cortex (SI) of primates by repetitive delivery of a tactile stimulus is distinctly patchy. The functional significance of these patches, however, remains obscure. This investigation sought to determine the correlation between neural and metabolic activity produced by tactile stimuli and to evaluate the relationship, if any, between the neural activity and metabolic patches evoked by similar stimuli. Experiments were undertaken in which extracellular microelectrode recordings were carried out in animals that subsequently underwent a 2‐deoxyglucose (2DG) study. Three types of relations were identified. First, the receptive fields (RF) and modality properties of neurons sampled in locations at which patches of metabolic label were found matched the “place” and “modal” properties of the stimulus used to produce 2DG labeling. Second, in cortical locations where the RF and modality properties of the sampled neurons differed from either the place or modal properties of the stimulus used to evoke the 2DG label, no above‐background increases in metabolic labeling were found. Finally, in some cortical locations at which the receptive field and modality properties of the neurons matched those of the 2‐deoxyglucose mapping stimulus, no above‐background increases in metabolic labeling were found. This outcome leads us to suggest that moment‐to‐moment changes in neural responsivity, which might remain undetected by conventional receptive field mapping methods, contribute to the patchy pattern of metabolic activity visualized by the 2‐deoxyglucose method.
Association of neuroactive peptides with the protein secretory pathway in identified neurons of Aplysia californica: Immunolocalization of SCPA and SCPB to the contents of dense‐core vesicles and the trans face of the Golgi apparatus
Authors: Reed William , Weiss Klaudiusz R. , Lloyd Philip E. , Kupfermann Irving , Chen Mary , Bailey Craig H. 
Published: May 2005

AbstractThe subcellular distribution of two molluscan neuropeptides, the small cardioactive peptides A and B (SCPA and SCPB), has been determined in two identified Aplysia buccal ganglion neurons, B1 and B2. These neurons were previously shown to synthesize and release these neuropeptides. B1 and B2, identified by their size and location within the ganglion, were labeled by intrasomatic injection of an electron‐dense particulate marker (ferritin or Imposil) permitting the unequivocal identification of their somata and proximal processes in thin sections. The somatic cytoplasm of both neurons had a conspicuous population of large dense‐core vesicles along with a smaller number of compound vesicles and small lucent vesicles. All three vesicle types are found in the neurites within the neuropil and proximal axon in the esophageal nerve. Immunoreactivity was localized on the surface of thin sections by the indirect immunogold method. The primary antiserum was shown to recognize both SCPA and SCPB after the neuropeptides had been immobilized on protein‐coated nitrocellulose membranes by means of glutaraldehyde, the primary fixative used to immobilize SCPA and SCPB in situ. SCP immunoreactivity was present in the lumens of the dense‐core vesicles distributed throughout the cytoplasm of B1 and B2 and in dense‐core regions of the Golgi apparatus in the somatic cytoplasm. Taken together with biochemical evidence that B1 and B2 synthesize and release SCPs, these data suggest that the neuropeptides are sequestered into the protein secretory pathway of B1 and B2, a distribution that supports the notion that the SCPs function physiologically as neurotransmitters or neuromodulators.
Regional and laminar distribution of the dopamine and serotonin innervation in the macaque cerebral cortex: A radioautographic study
Authors: Berger B. , Trottier S. , Verney C. , Gaspar P. , Alvarez C. 
Published: May 2005

AbstractThe regional density and laminar distribution of dopamine (DA) and serotonin (5‐HT) afferents were investigated in the cerebral cortex of cynomolgus monkeys using a radioautographic technique that is based on the high affinity uptake capacity of these aminergic neurons. Large vibratome sections, 50 μm thick, were incubated with [3H] DA (0.2 μM) and desipramine (5 μM) or with unlabeled norepinephrine (5 μM) and [3H] 5‐HT (0.6 μM), which allowed for the specific labeling of the DA and 5‐HT innervations, respectively. After fixation, these sections were dried, defatted, and radioautographed by dipping. Semiquantitative data on the DA innervation also were provided by counting [3H] DA‐labeled axonal varicosities in radioautographs from 4‐μm‐thick sections of the slices obtained after epon embedding.The DA innervation was widespread and differed in density and laminar distribution in the agranular and granular cortices. DA afferents were densest in the anterior cingulate (area 24) and the motor areas (areas 4, 6, and supplementary motor area [SMA]). In the latter they displayed a trilaminar pattern of distribution, predominating in layers I, IIIa, and V‐VI, with characteristic cluster‐like formations in layer IIIa, especially in the medial part of motor areas. In the granular prefrontal (areas 46, 9, 10, 11, 12), parietal (areas 1, 2, 3, 5, 7), temporal (areas 21, 22), and posterior cingulate (area 23) cortices, DA afferents were less dense and showed a bilaminar pattern of distribution, predominating in the depth of layer I and in layers V‐VI; density in layers II, III, and IV was only 20% of that in layer I. The lowest density was in the visual cortex, particularly in area 17, where the DA afferents were almost restricted to layer I.The density of 5‐HT innervation was generally greater than that of DA except in the motor areas and in the anterior cingulate cortex. Regionspecific laminar patterns characterized (1) motor areas where a lower density in layer III contrasted with the clusters of DA axons in the same layer; (2) the primary visual cortex (area 17), where two bands of higher density in layers III‐IV and layer V outlined a poorly innervated zone in layer IVc‐β (3) the peristriate area 18, where the 5‐HT network was relatively loose but with a denser band in layer III.Thus, DA innervation of the cerebral cortex displays major differences between rodents and primates, characterized by expanded cortical targets and by a highly differentiated laminar distribution. This suggests a greater functional importance and a direct role of DA at the cortical level in the control of motor and higher order brain functions.