bluuebunny/crossref_metadata_2025_split huggingface dataset:
Central projections of C4–C8 dorsal root ganglia in the rat studied by anterograde transport of WGA‐HRP
Authors: Arvidsson J. , Pfaller K. 
Published: January 2005

AbstractInjections of WGA‐HRP were made in the rat C4–C8 dorsal root ganglia (DRGs) individually to study the central projections and their relations to each other. The main dorsal horn projections from these DRGs to the dorsal horn lamina II extended for about two segments rostrally and caudally to the injected DRG, whereas the projections to laminae I, III, and IV were less restricted rostrocaudally. Comparisons of the dorsal horn projections from the DRGs investigated indicated a tendency for a somatotopic organization, which was most prominent in lamina II. Labeled central branches from the C4–8 DRGs could be traced in the dorsal column as far caudally as 12‐17 segments caudal to the level of entrance. Most of these fibers appeared to end in the medial dorsal horn base, including the column of Clarke. Labeling of primary afferents in the ventral horn generally extended for at least 3‐4 segments rostral and caudal to the level of the injected DRG. Projections to the central cervical nucleus were most prominent from the C4 DRG and gradually became less prominent from the more caudal DRGs. Heavy projections to the cuneate nucleus (Cun) originated from the C7 and C8 DRG, whereas those from the C4–C6 DRGs were less extensive. The Cun projections from the different DRGs appeared to overlap, and the same was true for the projections to the external cuneate nucleus. Projections to the gracile nucleus, the vestibular nuclear complex, including nucleus X, and to trigeminal sensory nuclei were seen from all DRGs investigated.
Comparative neuroanatomy of the histaminergic system in the brain of the frog xenopus laevis
Authors: Airaksinen Matti S. , Panula Pertti 
Published: January 2005

AbstractThe distribution of the histaminergic neuronal system in the brain of the clawed frog Xenopus laevis was mapped with an antiserum against carbodiimide‐fixed histamine and compared to that in mammals. The histamine‐immunoreactive cell bodies were located in a small area of the posterolateral hypothalamus, close to the dorsal infundibular nucleus, which contains catecolaminergic and serotonergic neurons. This area may be homologous to the tuberomammillary nucleus in mammals. A thick process extended from each cell between the ependymal cell layer and terminated in the ventricle lumen. The number of histaminergic cell bodies in adult Xenopus brain was relatively low, as compared with the mammalian brain. Preliminary analysis of adjacent sections stained with antisera against GABA or serotonin indicated that the histamine cells were not immunoreactive for these.The pathways and distribution of histaminergic fibers in Xenopus brain showed many similarities to mammals. The densest fiber networks were present in the medial basal forebrain, particularly in the medial amygdala and septum. A distinct cluster of fibers was concentrated around the cell bodies of nucleus accumbens. In most pallial areas, the density was moderate to low. In the primordial piriform cortex and the striatum, very few fibers were seen. In diencephalon, highest fiber densities were found in the anterior and ventral thalamus and posterior and lateral hypothalamus. In hindbrain, the density was highest in the medullary central gray, as in some mammals.The results suggest that the general pattern of the histaminergic system in vertebrate brain is conserved from amphibians to mammals.
Postnatal gliogenesis in the nerve fiber layer of the rabbit retina: An autoradiographic study
Authors: Schnitzer Jutta 
Published: January 2005

AbstractCell proliferation was studied in the retina of rabbits at various postnatal stages. Autoradiography was performed with animals that received a single injection of 3H‐thymidine and were sacrificed 1 hour later. This short survival time allowed the determination of the position of a cell undergoing DNA synthesis at that moment.Between birth and day 6, cells engaged in DNA synthesis were seen in the inner nuclear layer (INL) of the entire retina. Cytogenesis ceases in this layer after the first postnatal week. Few labeled cells were detectable in the INL at day 9; these were found close to the ora serrata. Thus neurogenesis, which is known to occur in this layer of the retina, ceases by that time.In the nerve fiber layer (NFL), labeled cells were found at all ages between birth and day 27, which was the oldest stage examined in this study. By using horizontal sections through the NFL of entire retinae, it was observed that almost all labeled cells were confined to the medullary ray region, which is the neuroglia (astrocyte and oligodendrocyte)‐ bearing part of the NFL. Microglial cells, the only cellular elements present in the NFL outside the medullary ray region, were rarely labeled, and thus do not play a major role in gliogenesis occurring in the NFL. In addition to neuroglia, some endothelial cells were labeled after day 9. It is concluded that gliogenesis taking place in the NFL persists after the cessation of neurogenesis, suggesting that both processes occur independently.
Vomeronasal and olfactory nerves of adult and larval bullfrogs: I. Axons and the distribution of their glomeruli
Authors: Burton Paul R. , Coogan Mary M. , Borror Cheryl A. 
Published: January 2005

AbstractThe distribution of primary olfactory and vomeronasal (VMN) glomeruli is demonstrated in the forebrain of the larval (stage III tadpole) and adult bullfrog. Olfactory glomeruli are massed at the anterior end of the olfactory bulb; farther posterior, they are located at the periphery and then become distributed in a superficial layer all along the ventral surface of the bulb. Glomeruli of the accessory olfactory bulb (AOB) of the tadpole are less compact and show larger dendritic profiles and fewer synaptic junctions per unit area than those of the adult AOB. Axons of both tadpole and adult VMN nerve are ultrastructurally indistinguishable from those of the primary olfactory nerve; in comparing VMN axons of tadpole and adult, however, differences were observed in the number of neurofilament profiles in axons at the proximal and distal ends of the VMN nerve. Counts of neurofilament profiles in the two ends of the nerve suggest that neurofilament segments accumulate near terminations of their axons. The VMN nerve of tadpole and adult frog are roughly the same size, and calculations indicate that they contain comparable numbers of axons. The primary olfactory nerve of the tadpole is estimated to contain about 660,000 axons; the adherent VMN nerve of the tadpole contains about 270,000 axons (a ratio of about 2.5:1). In the adult, the ratio of primary to VMN axons is about 64:1, reflecting the quantitative growth of the primary olfactory nerve with development from an aquatic tadpole to an air‐breathing adult.
Met5‐enkephalin‐Arg6‐Gly7‐Leu8‐like immunoreactivity in the pelvic ganglion of the male rat: A light and electron microscopic study
Authors: Wang Bai‐Ren , Senba Emiko , Tohyama Masaya 
Published: January 2005

AbstractBy using both light and electron microscopic immunocytochemical methods, Met5‐Enkephalin‐Arg6‐Gly7‐Leu8 (MEAGL)‐like immunoreactive structures were detected in the pelvic ganglion of male rats. Denervation studies were carried out to determine the origin of these immunoreactive fibers and the projection of immunoreactive neurons within the pelvic ganglion. MEAGL‐like immunoreactivity was found in numerous axon boutons, some small, intensely fluorescent (SIF) cells, and a few principal ganglion neurons. Most of the immunoreactive nerve fibers formed pericellular plexuses surrounding the ganglion cells. In addition, there were a few scattered varicose fibers. These fiber plexuses could be classified into two types: type I (∼90% of fibers), which consisted of 80‐120 small boutons that synapsed on either the dendrites (80% of cases) or somata (20% of cases) of principal neurons; and type II (∼10% of fibers), which consisted of 20‐40 larger boutons that formed axodendritic synapses exclusively. After transection of the hypogastric and pelvic nerves, virtually all of the pericellular fiber remained. According to their ultrastructure, these remaining fibers were considered to arise from SIF cells. Following the injection of Fast Blue into the bladder wall, some of the MEAGL‐like immunoreactive principal neurons were retrogradely labeled. The results of this study indicate that there are two origins for the MEAGL‐like immunoreactive fibers detected in the pelvic ganglion: most arise from preganglionic neurons in the spinal cord, and a small proportion may originate from intraganglionic MEAGL‐like immunoreactive SIF cells or principal neurons. Some MEAGL‐like immunoreactive principal neurons may project to the urinary bladder.
Region‐specific consequences of PCD gene expression in the olfactory system
Authors: Baker Harriet , Greer Charles A. 
Published: January 2005

AbstractThese studies investigated the response of olfactory bulb juxtaglomerular dopamine neurons to the loss of mitral cells in 6–7–month‐old Purkinje cell degeneration (PCD) mice. Previous studies in normal mice, with tyrosine hydroxylase (TH) enzyme as a marker, demonstrated that following peripheral olfactory afferent denervation in TH activity and immunoreactivity. These intrinsic dopamine neurons also receive afferent input via dendrodendritic contacts with mitral cells. In contrast to the deficits produced by peripheral denervation, following mitral cell degeneration in homozygous recessive PCD mice, TH activity and immunoreactivity were unaltered as compared to normal heterozygous littermates. Moreover, TH activity in the substantia nigra also was unchanged, thus suggesting that the dopamine phenotype is resistant to the influences of the pcd gene. Despite the absence of a well‐defined effect of the pcd gene on neurons earing the TH phenotype, the expression of this mutation within the olfactory system is not limited to mitral cell degeneration. The current studies also demonstrate the absence of the anterior commissure, especially pars anterior, in homozygous recessive PCD mice at 6–7 months postnatal. Whether or not the loss of the anterior commissure is a primary effect or one that is secondary to mitral cell degeneration, this structural alteration provides evidence that the pcd gene exerts more widespread effects within the olfactory system than previously appreciated. The neuronal specificity of those effects remains apparent as indicated by the lack of change in TH expression.
Heterogeneity of chandelier neurons in monkey neocortex: Corticotropin‐releasing factor‐and parvalbumin‐immunoreactive populations
Authors: Lewis David A. , Lund Jennifer S. 
Published: January 2005

AbstractChandelier neurons are a unique subclass of cortical nonpyramidal neurons. The axons of these neurons terminate in distinctive vertically arrayed cartidges that synapse on the axon initial segment of pyramidal neurons. In this study, the rapid Golgi method and immunohistochemical techniques were used to characterize the morphology, regional distribution, laminar location, and biochemical content of chandelier neurons in the prefrontal and occipital cortices of three monkey species. As in our previous studies of visual areas V1 and V2 (Lund:Journal of Comparative Neurology 257:60‐92, 1987; Lund et al.:Journal of Comparative Neurology 202:19‐45, 1981, 276:1‐29, 1988), Golgi impregnations of areas 46 and 9 of macaque prefrontal cortex show chandelier neurons to be present in layers 2 through superficial 5. The vertical arrays of terminal boutons (axon cartridges) typical of this neuron class are also present in layers 2‐6 of the prefrontal cortex, but are not found in layer 1 or the subcortical white matter. In immunohistochemical studies, a calcium‐binding protein, parvalbumin, and a neuropeptide, corticotropin‐releasing factor (CRF), identify rod‐like structures that are morphologically similar to the axon cartridges of chandelier neurons seen in the Golgi material. In addition, both parvalbumin‐and CRF‐immunoreactive cartridges are located below the somata of unlabeled pyramidal neurons and appear to outline the axon initial segment of these neurons. However, we find that parvalbumin and CRF are present in only subpopulations of chandelier axon cartridges. For example, in adult primary visual cortex, parvalbumin‐labeled cartridges are present in very low numbers only in layers 2‐3, whereas in prefrontal and occipital association cortices these cartridges are a very prominent component of layers 2‐superficial 3 and are present in much lower density in the deeper cortical layers. In contrast to these findings in adult macaque monkeys, prefrontal and occipital association cortices of infant macaque monkeys contain a very high density of parvalbumin‐labeled cartridges in layer 4 and relatively few in the superficial cortical layers. Furthermore, in adult squirrel monkey prefrontal cortex, CRF‐labeled cartridges are predominately present in layer 4, but these CRF‐immunoreactive structures have not been observed in the homologous regions of infant or adult macaque monkeys. These findings indicate that even for neurons of such distinctive morphology and presumably constant functional role as chandelier neurons, factors such as regional and laminar location, age, and primate species are associated with differences in the biochemical content of subpopulations of these neurons.
Development of the electrosensory nervous system of Eigenmannia (gymnotiformes): II. The electrosensory lateral line lobe, midbrain, and cerebellum
Authors: Lannoo Michael J. , Maler Leonard , Vischer Heinrich A. 
Published: January 2005

AbstractThe somatotopically and functionally organized electrosensory system of gymnotiform teleosts provides a model for the study of the formation of ordered nerve connections. This paper describes the development of the major electrosensory nuclei within the hind‐ and midbrain. All three main electrosensory nuclei‐the electrosensory lateral line lobe (ELL), dorsal torus semicircularis (torus), and tectum‐grow by adding cells at their caudolateral borders. Toral and tectal germinal zones arise from lateral ventricular outpocketings that either completely or partially close by maturity. In the ELL before day 5 postspawning, germinal cells form from an initial periventricular germinal zone, then migrate to the caudolateral border of the hindbrain and begin dividing. The ELL grows from two main germinal zones, one for the medial segment, and one for the three lateral tuberous segments. Within each ELL germinal zone, newly formed cells arise from two areas: granular cells arise from a ventral subzone, pyramidal cells are generated more dorsally. Granular cells remain in situ, whereas pyramidal cells may migrate rostromedially. Cells begin differentiating as soon as they are formed. Spherical and pyramidal cells send ascending axons into the internal plexiform layer by day 14–18 and the ELL gradually begins to assume its mature laminar appearance.The ELL grows caudally, preceding the caudal lobe of the cerebellum, which will eventually lie over and fuse with it. Primary electrosensory afferents enter the ELL by day 6: incoming afferents form four fascicles within the ELL, suggesting the formation of separate ELL segments. Unlabelled projections between labelled fields from a single nerve branch filled with HRP on day 7 suggest that somatotopic order is already present at this early age.In the periphery, receptor addition is unordered, occurring along nerve branch pathways. Meanwhile the ELL adds cells in an orderly fashion at its caudolateral border. This suggests that primary afferents shift position caudally with growth to maintain their somatotopic relationships. Because all three central nuclei are in topographic register and grow by adding cells caudally, during growth ELL efferents to the torus and toral efferents to the tectum may utilize pessive mechanisms, such as fiber‐fiber interactions, to guide axons.
Subnuclear organization of the lateral tegmental field of the rat. I: Nucleus ambiguus and ventral respiratory group
Authors: Ellenberger H. H. , Feldman J. L. 
Published: January 2005

AbstractThree classes of neurons within the lateral tegmental field of the rat medulla having different target projections were identified by retrograde labelling with three different fluorescent tracers. Labelled bulbospinal premotor and propriobulbar interneurons of the ventral respiratory group and vagal motoneurona of nucleus ambiguus formed partially intermingled longitudinal columns encompassed within a common region of the lateral tegmental field. Labelled neurons of each class were organized in a nonuniform distribution within these columns forming subdivisions distinguished by neuron morphology, orientation, and target projection. The three major rostrocaudal divisions of the ventral respiratory group (VRG) previously identified in the cat and rabbit were identified here in the rat, suggesting a common pattern of VRG organization among these species.
Efferent projections of the subthalamic nucleus in the squirrel monkey as studied by the PHA‐L anterograde tracing method
Authors: Smith Y. , Hazrati L.‐N. , Parent A. 
Published: January 2005

AbstractThe organization of the efferent connections of the subthalamic nucleus was studied in the squirrel monkey (Saimiri sciureus) by using the lectin Phaseolus vulgaris‐leucoagglutinin (PHA‐L) as an anterograde tracer. At the level of the basal forebrain, anterogradely labeled fibers and axon terminals were mostly found in the striatopallidal complex and the substantia innominata. In cases in which the PHA‐L injection sites were placed in the central or the lateral third of the subthalamic nuclus, numerous anterogradely labeled fibers were seen to arise from the injection loci and innervate massively the globus pallidus. At pallidal levels the fibers formed bands lying parallel and adjacent to the medullary laminae. The number and the complexity of the topographical organization of these bands varied with the size and the location of the PHA‐L injection site. When examined at a higher magnification, the bands of subthalamopallidal fibers appeared as rich plexuses of short axon collaterals with small bulbous enlargements that closely surrounded the cell bodies and primary dendrites of pallidal cells. In contrast, PHA‐L injection involving the medial tip of the subthalamic nucleus did not produce bandlike fiber patterns in the globus pallidus. Instead, the labeled fibers formed a diffuse plexus occupying the ventral part of the rostral pole of the globus pallidus as well as the subcommissural pallidal region. The substantia innominata contained a moderate number of labeled fibers and axon terminals following injection of PHA‐L in the medial tip of the subthalamic nucleus. A small to moderate number of anterogradely labeled fibers were seen in the putamen after all PHA‐L injections. These subthalamostriatal fibers were long, linear, and branched infrequently. At midbrain level the substantia nigra contained a significant number of anterogradely labeled fibers and axon terminals following PHA‐L injection in the subthalamic nucleus. The subthalamonigral fibers descended along the ventromedial part of the cerebral peduncle and swept laterally to reach their target. Most of these fibers formed small plexuses along the base of the pars reticulata, whereas a few others ascended along the cell columns of the pars compacta that impinged deeply within the pars reticulata. More caudally in the brainstem, a small number of fibers occurred in the area of the pedunculopontine nucleus and in the periaqueductal gray. These findings indicate that besides its well‐known connection with the pallidum, the subthalamic nucleus gives rise to widespread projections to other components of the basal ganglia in primates.
VIP‐and PHI‐immunoreactivity in olfactory centers of the adult cat
Authors: Sanides‐kohlrausch Claudia , Wahle Petra 
Published: January 2005

AbstractThe purpose of the study was to determine the morphology and distribution of vasoactive intestinal polypeptide‐ and peptide histidine isoleucineimmunoreactive (VIP‐ and PHI‐ir) neurons and innervation patterns in the main and accessory olfactory bulb, anterior olfactory nucleus, and piriform cortex of the adult cat. In these centers, VIP‐ and PHI‐immunoreactive material are present in the same neuronal types, respectively, therefore summarized as VIP/PHI‐ir neurons. In the main olfactory bulb, the majority of VIP/PHI‐ir neurons are localized in the external plexiform layer. These neurons give rise to two or more locally branching axons. They form boutons on mitral and external tufted cell bodies. According to the morphology and location, we have classified these neurons as Van Gehuchtencells. Some VIP/PHI‐ir neurons are present in the glomerular layer. They have small somata and give rise to dendrites branching exclusively into glomeruli. We have classified these neurons as periglomerular cells. In the granule cell layer, neurons with long apical dendrites and one locally projecting axon are present. In the accessory olfactory bulb, VIP/PHI‐ir neurons are localized in the mixed external/mitral/internal plexiform layer. They represent Van Gehuchten cells.In the anterior olfactory nucleus and piriform cortex, VIP/PHI‐ir bipolar basket neurons are present. They are localized mainly in layers II/III. These neurons are characterized by a bipolar dendritic pattern and by locally projecting axons forming basket terminals on large immunonegative cell somata. Because of their common morphological features, we summarize them as the retrobulbar VIP/PHI‐ir interneuron population.The PHI‐ir neurons display the same morphology as the VIP‐ir cells. However, they are significantly lower in number with a ratio of VIP‐ir to PHI‐ir cells about 2:1 in the main and accessory olfactory bulb and in the anterior olfactory nucleus. By contrast, in the piriform cortex the ratio is about 1:1.