bluuebunny/crossref_metadata_2025_split huggingface dataset:
Excitatory transmitter amino acid‐containing neurons in the rat visual cortex: A light and electron microscopic immunocytochemical study
Authors: Dori Ioanna , Petrou Mario , Parnavelas John G. 
Published: January 2005

AbstractThe distribution and morphology of neurons labelled with antisera to glutamate or aspartate were examined, at the light and electron microscope levels, in the rat visual cortex. Using widely accepted light microscopic features as well as well‐established nuclear, cytoplasmic, and synaptic criteria, we noted that glutamate‐immunoreactive neurons were pyramidal cells distributed in layers II‐VI, with an increased concentration in layers II and III. Aspartate immunoreactivity was localized chiefly to pyramidal neurons in layers II‐VI. However, approximately 10% of immunolabelled cells were nonpyramidal neurons scattered throughout the cortex. Cell‐body measurements revealed that, for both groups of neurons, layer V contained the largest labelled neurons, whereas layers IV and VI contained the smallest. Furthermore, in every layer, aspartate‐stained neurons were larger than glutamate‐positive cells. Finally, glutamate‐ and aspartate‐labelled axon terminals formed asymmetrical synapses, which are presumably excitatory in nature, primarily with dendritic spines. These findings, together with recent detailed studies of the projections of glutamate‐ and aspartate‐labelled cortical neurons, may provide essential background information for studies aimed to elucidate the function(s) of excitatory amino acids in the cortex and their role in pathological conditions.
Ultrastructural analysis of the development and maturation of synapses and subsynaptic structures in the ectostriatum of the zebra finch
Authors: Nixdorf Barbara E. 
Published: January 2005

AbstractThe development of synapses and subsynaptic features in the neuropil of the ectostriatum, a visual projection area in birds, was examined ultrastructurally at 5, 10, 20, and 100 days posthatching. The maturation of the synaptic complex is accompanied by a variety of different dynamic processes. The number of synapses in ectostriatum and the number of specific synaptic types vary with age as does the constellation of subsynaptic structures. At day 5, before eye opening, the total number of synapses is 16% of the adult value. These synapses, unlike synapses seen at maturity, have indistinct synaptic contact zones and generally are associated with few synaptic vesicles. Synapse number increases continuously until 20 days of age, paralleled by a steady increase of the observed brain volume. The largest increase in synapse number takes place during the time of eye opening (i.e., between 5 and 10 days). This increase is mainly due to an increase of asymmetric synapses, the most common type in the neuropil of ectostriatum (90% of the synapse population). At day 20 the number of synapses has reached its maximum and remains high in adulthood. Synapses on spines are more prominent in younger animals than in adults. The percentage of presynaptic terminals involved in synaptic contact with more than one postsynaptic element (multiple synapses) shows a significant reduction from 12% to 4% early in development (between days 10 and 20). Presynaptic terminal size and postsynaptic density (PSD) length increase until 20 days of age. From day 20 to adulthood the PSD shows a 10% reduction in contact length, and the presynaptic terminal further increases in size by 27%. Therefore, the pre‐ and postsynaptic structures described above continue to develop after the number of synapses remains constant.
Morphology of neuropeptide y‐immunoreactive neurons in the cat olfactory bulb and olfactory peduncle: Postnatal development and species comparison
Authors: Sanides‐Kohlrausch Claudia , Wahle Petra 
Published: January 2005

AbstractThe distribution and morphology of Neuropeptide Y ‐immunoreactive (NPY‐ir) neurons in the olfactory bulb and the olfactory peduncle was studied in the adult cat and rat, and the common marmoset Callithrix jacchus. Significant species differences were not observed. In all three species, the population of NPY‐ir neurons is localized in the white matter extending from the main olfactory bulb to the border of the striatum. The neurons are characterized by a conspicuously looping axonal ramification pattern with some major collaterals running toward the olfactory bulb and others running toward the internal olfactory tract. The former, ipsilateral projection terminates in the granule cell layer of the main and accessory olfactory bulb and in layer II/III of the anterior olfactory nucleus. Reconstruction of the latter projection has revealed that the fibers are continuous with the olfactory limb of the anterior commissure and the anterior commissure proper suggesting a commissural contralateral projection. The analysis of the postnatal development of the cat NPY neuron system supports this assumption in a very clear‐cut way. In young animals growing fibers are observed to cross the brachium of the commissure.The NPY neuron system develops postnatally. The maximum cell number is reached during the third postnatal week. The appearance of more and more NPY‐ir neurons slightly precedes the formation of the terminal fields and of the fiber projection in the internal olfactory tract. The density of this early fiber projection by far exceeds the fiber density observed in the adult. Later in development the fiber density in the olfactory limb and the anterior commissure becomes considerably reduced. In contrast, the plexus density in the anterior olfactory nucleus and the granule cell layer of the main and accessory olfactory bulb undergoes only a slight reduction, and the NPY‐ir cell number remains roughly constant. These observations suggest that the ipsilateral NPY‐ir projection remains largely unchanged, in contrast to the contralateral projection, which exists to a large extent only for the first four postnatal months.The observation that the NPY neuron system gives rise to a contralateral projection does not support a classification of NPY neurons as short axon cells.
Effects of protein deprivation on pyramidal cells of the visual cortex in rats of three age groups
Authors: Díaz‐Cintra S. , Cintra L. , Ortega A. , Kemper T. , Morgane P. J. 
Published: January 2005

AbstractThe effect of protein deprivation on rapid Golgi impregnated pyramidal neurons in layers II/III and V of the rat visual cortex was studied at 30, 90, and 220 days of age using morphometric methods. In order to mimic human undernutrition female rats were adapted to either an 8% or control 25% casein diet 5 weeks prior to conception and maintained on these diets during gestation and lactation. The pups were then weaned and maintained on their respective diets. The undernourished rats showed a significant decrease in brain weight only at 90 days, indicating that the protein deprivation had a mild effect on brain development. Crrespondingly, the number of significant histological differences between the two diet groups were least at 30 and 220 days of age. The effect of the diet was greater on layer V than on layer II/III pyramids. At 30 days of age the effect of the diet was different on the pyramids of these two cell layers, at 90 days there was a mixture of similar and dissimilar effects, and at 220 days the pyramids of these two cell layers showed only minor differences between the two diet groups. Analysis of age‐related changes indicated that the effect of the diet was different on layer II/III pyramids compared to layer V pyramidal cells. These different effects apparently accounted for the progression from a dossimilar effect of the diet at 30 days on the pyramids of the two cell layers to only minor differences between them at 220 days. Further analysis of these age‐related changes shows that two prominent effects of protein deprivation are for age‐related changes to occur in undernourished rats but not in controls and for age‐related changes to be out‐of‐phase with each other in the two diet groups. From these findings, and a review of similar studies in the literature, we propose that these mechanisms are a prominent effect of undernutrition in the post‐weaning period and help account for the unexpected increases in morphometric measurements noted in undernourished rats in this and other studies.
Organization and actions of the noradrenergic input to the hamster's superior colliculus
Authors: Mooney Richard D. , Bennett‐Clarke Carol , Chiaia Nicolas L. , Sahibzada Niaz , Rhoades Robert W. 
Published: January 2005

AbstractImmunocytochemistry using antisera directed against dopamine‐hydroxylase (DBH) was used to determine the organization of the noradrenergic (NE) input to the hamster's superior colliculus (SC). Immunocytochemistry for DBH was combined with retrograde transport of fluorogold (FG) to determine the sources of NE input to SC. Microiontophoretic techniques were used together with extracellular single unit recording and receptive field mapping techniques to determine the manner in which NE influenced the responses of individual SC neurons. The hamster's SC contained numerous DBH‐positive fibers but no immunopositive cells. These fibers formed a plexus that was most dense in the lower stratum griseum superficiale SCS. The density of DBH‐positive fibers was very low in the stratum opticum SO and increased in density in the stratum griseum intermediale SGI and the other deep layers. When FG injections into the SC were combined with immunocytochemical detection of DBH, double‐labeled cells were observed in the contralateral locus ceruleus. DBH‐positive neurons were observed in several other portions of the mesencephalon and pons, but none of these were labelled with FG. The effects of NE iontophoresis were assessed for a total of 135 SC neurons. In 74% N = 100, NE reduced spontaneous and/or stimulus evoked activity. In 3% (N = 4 cells), NE increased activity, and in 23%; N = 31 cells it had no effect. These percentages were essentially the same for superficial layer visual cells and somatosensory neurons in the deep laminae. The effect of NE iontophoresis upon signal to noise ratios was assessed for 46 visual and 56 somatosensory neurons. For 54% (N = 25) of the visual cells and 16% N = 9 of the somatosensory cells, NE iontophoresis decreased signal to noise ratios. For 13% N = 6 of the visual cells and 21% N = 12 of the somatosensory cells, NE iontophoresis increased signal to noise ratios. The effects of NE on the responsivity of SC neurons were antagonized by propranolol 86% of the 21 cells tested, sotalol 67% of the six cells tested, and atenolol effective in the single cell tested. All these agents are β‐adrenergic antagonists. The single β‐adrenergic antagonist that we evaluated, corynanthine, potentiated the effects of NE on the responsivity of the two SC neurons that we tested.
Ultrastructural study of synapses at the time of neuronal migration and early differentiation in the tangential vestibular nucleus of the chick embryo in vivo
Authors: Petralia R. S. , Peusner K. D. 
Published: January 2005

AbstractThe chick tangential nucleus is a primary vestibular nucleus whose two main neuron types migrate and begin to differentiate between 5 and 8 days in the embryo (gestation takes 20‐21 days). Based on rapid Golgi impregnations of developing tangential neurons and growing fibers, we have identified ultrastructural counterparts and characterized interactions in the nucleus from 5 to 8 days.Developing tangential neurons received the earliest synapses at 5 days on their primitive processes and subsequently on their cell bodies by longitudinal fibers of unknown origins. In contrast, the primary vestibular afferents did not form identified synapses on the developing tangential neurons until 7½ days.In conclusion, the earliest synapses in the tangential nucleus are formed by longitudinal fibers, which are probably not primary vestihular afferents. Since a specific class of fibers forms particular synapses on the tangential neuron precursors at predictable times prior to and during neuronal migration and also at the onset of differentiation, the role of these synapses in developmental events should be explored.
Bulbospinal serotoninergic pathways in the frog rana pipiens
Authors: Tan Hongjing , Miletic Vjekoslav 
Published: January 2005

AbstractWe combined retrograde fluorescent tracing with rhodamine immunofluorescence to identify the origin of serotoninergic neurons with descending projections to the spinal cord of frogs. After injections of Fluoro‐gold into the spinal cord, retrogradely labeled immunoreactive serotoninergic neurons were detected in the caudal part of the brainstem from the level of the obex through the level of the VIII nerve. These doubly labeled cells were distributed along the midline throughout the rostrocaudal extent of the dorsal portion of the raphe nuclear region. Doubly labeled neurons were more numerous in the rostral than in the caudal part of the raphe area.The fluorescent tracer 1,1′‐dioctadecyl‐‐3,3,3′3′‐tetramethylindocarbocyanine perchlorate (DiI) was then placed in and around the middle and rostral raphe nuclear region. Anterogradely labeled fibers could be traced bilaterally in the lateral portion of the dorsal funiculus and the lateral and ventral funiculi. These fibers were seen terminating in the dorsal and ventral horns, as well as in the intermediate grey matter. After placement of DiI in the caudal raphe area, labeled fibers were found only in the intermediate grey and ventral horn.These findings suggest that the organization of bulbospinal serotoninergic pathways in the frog is similar to that of mammals, and that an isolated amphibian spinal cord preparation could be a useful model for pharmacological and physiological studies of the action of serotonin (5HT) in the spinal cord.
Analysis of taste bud innervation based on glycoconjugate and peptide neuronal markers
Authors: Silverman James D. , Kruger Lawrence 
Published: January 2005

AbstractPrimary gustatory neurons and their peripheral and central processes were evaluated histochemically in the geniculate and petrosal cranial nerve ganglia, lingual fungiform taste buds, and the nucleus of the solitary tract (NST) using (1) the plant lectin Griffonia simplicifolia I‐B4, which binds specifically to D‐galactose residues and selectively labels primarily nonpeptidecontaining peripheral somatosensory neurons, and (2) calcitonin gene‐related peptide immunoreactivity (CGRP‐IR), which labels most peptidergic somatosensory neurons.Lectin reactivity was expressed by the vast majority of geniculate and petrosal ganglion cells, while CGRP‐IR labeled very few cells. Peripherally, gustatory intragemmal axons penetrating fungiform taste buds were labeled only by the lectin and were depleted following chorda tympani transection. However, both lectin‐labeled and CGRP‐IR subpopulations of somatosensory perigemmal axons surrounding the taste buds were observed and were eliminated by section of the lingual nerve. The differing brainstem projection patterns of lectin‐reactive vs. CGRP‐IR central axons reflected their distinct ganglionic origins and the differential distributions of lectin reactivity and CGRP‐IR among taste buds. Central lectin‐reactive terminals were found throughout the entire rostrocaudal extent of the NST, including its rostral lateral “gustatory” zone; the extensive lectin‐reactive visceral afferent projection can be presumed to have originated mainly from the large proportion of lectinlabeled neurons in the nodose ganglion. The lectin also prominently and selectively labeled the area postrema. CGRP‐IR central terminals, however, was relatively sparse and restricted primarily to the caudal and medial “visceral” divisions of the NST.The results are discussed with respect to the possible functional implications of cell surface glycoconjugate expression by gustatory axons innervating taste bud receptor cells of the tongue.
Immunohistochemical subpopulations of retinopetal neurons in the nucleus olfactoretinalis in a teleost, the whitespotted greenling (Hexagrammos stelleri)
Authors: Uchiyama Hiroyuki 
Published: January 2005

AbstractTwo subpopulations of retinopetal neurons in the nucleus olfactoretinalis (NOR) were revealed by means of general histological, tract tracing, and immunohistochemical methods in a marine teleost, the whitespotted greenling (Hexagrammos stelleri). Two types of cells in the NOR (M cell, L cell) were morphologically distinguishable from one another. The cell bodies of M cells were medium‐size and fusiform, while those of L cells were large and ellipsoidal or irregular. M cells were located at the ventralmost region of the junction between the olfactory bulb and telencephalon, while L cells were scattered more rostrally along the ventromedial surface of the olfactory bulb. Following applications of HRP or Fluoro‐Gold to the optic nerve, almost all M cells and about half of the L cells were labeled in the contralateral NOR. L cells showed strong immunoreactivities to gonadotropin releasing hormone (GnRH) and Phe‐Met‐Arg‐Phe‐NH2 (FMRFamide), whereas M cells showed only weak GnRH‐immunoreactivity and no FMRFamide‐immunoreactivity. Axons of L cells were detected in the optic nerve by means of GnRH‐ and FMRFamide‐immunohistochemistry. The axons were concentrated in the myelinated edge (the oldest area) of the “ribbon” optic nerve. GnRH‐ and FMRFamideimmunoreactive fibers constituted a plexus at the junction between the inner nuclear layer and inner plexiform layer. The existence of two structurally separate classes of NOR cells suggests two functionally separate channels from the NOR to the retina.
Somatostatin‐immunoreactive cells in the adult cat retina
Authors: White C. A. , Chalupa L. M. , Johnson D. , Brecha N. C. 
Published: January 2005

AbstractPeptides have been found in the retinas of all mammalian species studied to date, but little is known about their localization and function in the cat. Using two mouse monoclonal antibodies directed to somatostatin 14, we have observed two sparse groups of somatostatin‐immunoreactive neurons in the cat, both distributed preferentially in the inferior retina. The more numerous cell type is characterized by a small‐ to medium‐sized soma (mean diameter = 16.3 =9.0 μm; n = 186) with sparsely branching, far‐reaching varicose processes that ramify mainly in the inner plexiform layer. The majority of these cells are located in the ganglion cell layer, with the remainder in the proximal inner nuclear layer and the inner plexiform layer. They are in especially high density at the retinal margin. In morphology and soma size, these cells resemble wide‐field amacrine cells. The second cell type has a large, granular‐staining soma (mean diameter = 29.7 ± 14.8 μm; n = 145) with poorly stained primary processes and is found only in the ganglion cell layer. Cells of this type are most similar in their size and morphology to alpha ganglion cells.In contrast to the location of somatostatin‐immunoreactive somata, a dense meshwork of immunoreactive processes was observed at all eccentricities within the inner plexiform layer, adjacent to the inner nuclear layer and to the ganglion cell layer. Labeled processes arising from the inner plexiform layer were also occasionally detected in the outer plexiform layer and the nerve fiber layer. Additional processes of unknown origin were observed in the nerve fiber layer and the optic nerve head. The extensive distribution of immunoreactive processes suggests that somatcstatin‐immunoreactive somata located preferentially in the inferior half of the retina have a widespread influence on neural activity.
Brainstem projection of the vestibular nerve in the guinea pig: An HRP (horseradish peroxidase) and WGA‐HRP (wheat germ agglutinin‐HRP) study
Authors: Burian M. , Gstoettner W. , Mayr R. 
Published: January 2005

AbstractWe explored the course and termination of primary vestibular afferent fibers within the brainstem of the guinea pig by means of anterograde axonal transport of horseradish peroxidase (WGA‐HRP). Primary vestibular afferent fibers distribute within the entire vestibular nuclear complex, with the exception of the dorsal part of the lateral vestibular nucleus. The superior vestibular nucleus is characterized by the concentration of terminals within its central part. Although terminal labeling is weaker within the periphery, no area completely lacks primary input. The lateral vestibular nucleus can be divided into a ventral and a dorsal part; within the ventral part small and giant cells receive primary afferent fibers, whereas no significant terminal labeling occurs in the dorsal part. The medial vestibular nucleus shows the most uniform labeling, although the lateral part of its rostral third has a few more terminals than the medial half. Primary projection to the descending vestibular nucleus is widespread, although in its rostrodorsal part it is less impressive. Of the small cell groups commonly associated with the vestibular nuclear complex, only group y receives abundant primary input. Whereas group z completely lacks labeled fibers as well as terminals, single primary axons can be observed passing groups x and f. However, no terminals can be found within the borders of these two cell groups. Scanty projections can be detected within the prepositus hypoglossi nucleus, as well as within the external cuneate nucleus, the cochlear nucleus, the abducent nucleus, and parts of the reticular formation.
Morphological variability is a characteristic feature of granule cells in the primate fascia dentata: A combined Golgi/electron microscope study
Authors: Seress Laszlo , Frotscher Michael 
Published: January 2005

AbstractThis study analyzes the structural variability of granule cells in the monkey fascia dentata. The hippocampi of three adult rhesus monkeys (Macaca mulatta) and two 1‐year‐old female baboons (Papio anubis) were used for a combined Golgi/electron microscope (EM) study. The results were compared with other Golgi/EM studies on dentate granule cells in small laboratory animals.Whereas the granule cells in small rodents form a relatively uniform population of neurons, we observed a much greater variability of granule cell morphology in monkeys. This variability concerned the size of the cell body, the length and thickness of apical dendrites, the spine density, and the occasional occurrence of basal dendrites. The dendritic length of individual granule cells largely depended on their position in the highly convoluted granular layer. These convolutions caused significant variations in the thickness of the molecular layer and consequently in the length of individual granule cell dendrites. Granule cells with thick dendrites densely covered with spines could be differentiated from those exhibiting much thinner dendritic processes and moderate spine numbers. About 10% of granule cells in the monkey fascia dentata exhibited basal dendrites. Occasionally in the hilus ectopic granule cells were observed that gave rise to long apical dendrites traversing the granular layer. The axons of granule cells, the mossy fibers, entered the hilus, where they gave off several collaterals.In contrast to the light microscopic variability, subtypes of granule cells revealed similar fine structural characteristics, i. e., a round nucleus lacking indentations, a thin rim of cytoplasm, and characteristic spine formations. Large complex spines and smaller, “stubby” spines were observed on apical as well as basal dendrites. This suggests that characteristic spine formations were not induced by specific afferent fibers. All synaptic contacts on spines were of the asymmetric type, whereas both symmetric and asymmetric synapses occured on cell bodies and dendritic shafts.Unlike in rodents, we found a large variability of granule cells in the primate fascia dentata. This variability has to be considered in neropathological studies of this cell type.