bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatial and temporal patterns of oligodendrocyte differentiation in rat cerebrum and cerebellum
Authors: LeVine Steven M. , Goldman James E. 
Published: January 2005

AbstractOligodendrocytes are largely generated postnatally during mammalian CNS development. We have used a variety of antibodies to label immature neuroectodermal cells and developing oligodendrocytes in several areas of the rat CNS. Antibodies included those to GD3 ganglioside, a characteristic glycolipid of immature cells; carbonic anhydrase (CA), contained primarily in oligodendrocytes; and galactocerebroside and myelin basic protein, myelin components. Several aspects of oligodendrocyte development were examined: changes in shapes of immature cells with respect to time and to location within the brain, the sequential acquisition of the various markers, and possible sites of origin and pathways of precursor cell migration. Our observations suggest that oligodendrocytes in the forebrain and cerebellum arise from cells of the subventricular zone (SVZ) adjacent to the ventricles and migrate into and through nearby white and gray matter. During maturation, there are distinct patterns of morphological changes that correlate with time, locations of the cells in the brain, and acquisition of specific markers.
Sharpening of topographical projections and maturation of geniculocortical axon arbors in the hamster
Authors: Naegele Janice R. , Jhaveri Sonal , Schneider Gerald E. 
Published: January 2005

AbstractDuring specification of orderly neural maps, axons correctly navigate to their targets and form terminal arbors in topographically correct positions. To learn more about this mapping process, the patterns of geniculocortical topography were correlated with growth of axon arbors in the hamster visual cortex. Topography was studied by retrograde transport of WGA‐HRP from area 17 to the dorsal lateral geniculate nucleus (LGd) and visualized with TMB histochemistry. In separate experiments, geniculocortical axon arbors were filled with HRP deposited extracellularly into the optic radiations and stained with cobalt‐intensified DAB.On the day of birth (P0) and on P1–2, a crude topography was detected in the geniculocortical system. At these ages, geniculocortical axons coursed in the embryonic white matter of the visual cortex, parallel to the pia. During their passage, multiple short collaterals, with no terminal arbors, were extended into the subplate and deeper portions of the cortical plate. By P3–5, the topography was more precise and simple axonal arbors had now begun to be formed on some branches within the cortical plate. During the second postnatal week, branches in the white matter without terminals were eliminated and the ramifications of branches in the gray matter became more elaborate. The arbors continued to increase in complexity and resembled adult forms by P24.
Anatomy of glutamic acid decarboxylase immunoreactive neurons and axons in the rat medial geniculate body
Authors: Winer Jeffery A. , Larue David T. 
Published: January 2005

AbstractThis is a study of the form, density, and distribution of glutamic acid decarboxylase (GAD) immunoreactive neurons and puncta (axon terminals) in the adult rat medial geniculate complex. GAD‐positive elements were stained by either the peroxidase‐antiperoxidase or avidin‐biotin procedures. Thalamic architectonic subdivisions were defined independently in Golgi, Nissl, plastic‐embedded semi‐thin, and fiber‐stained preparations, and from investigations of medial geniculate connectivity.GAD‐positive neurons represent only ∼1% of medial geniculate neurons. They occur in the three major medial geniculate subdivisions (ventral, dorsal, and medial). There is variability between subdivisions in the form and number of such neurons, and among the puncta. In the ventral division, immunopositive somata may have sparsely branched dendrites as long as 300–400 μm and capped with varicose expansions or bouton‐like sprays of appendages. These closely appose the somata or primary dendrites of other cells; the axons of these GAD‐positive neurons are also immunostained. In the dorsal division there are fewer GAD‐positive neurons and their structure is different. Their dendrites are rarely immunoreactive for more than 100–150 μm; nor can their immunostained axons be traced very far. In the medial division the number of GAD‐positive neurons, considering the relatively small size of this division, was high. These neurons rarely have immunostained dendrites, and more than one type of neuron is immunoreactive.The average somatic diameter of GAD‐positive neurons is about 60% of that of non‐immunostained cells in semi‐thin material; however, the range of somatic area and the dendritic variability of these neurons suggest that cells representing more than one population are immunopositive and include all but the largest neurons.The puncta also show regional differences. Small (0.5–2 Cm in diameter), medium (2–3 μm), or large (> 3 μm) puncta occur. In the ventral division, the predominantly medium‐sized puncta are about four times as numerous on a unit/area basis than in the dorsal division, where they are far smaller and more delicate; medial division puncta are as numerous as those in the ventral division, but are much larger and coarser, and may form perisomatic arrangements. Controls were devoid of specific immunostaining.These data suggest that (1) there are significant local differences in the form and density of GABAergic neurons and puncta; (2) there is regional diversity in the form and size of such neurons; and (3) these local patterns might reflect differences in intrinsic organization, such as presynaptic dendrites in the ventral division and their probable absence in the medial division.
Organization of primary visual cortex (area 17) in the ferret
Authors: Law Margaret I. , Zahs Kathleen R. , Stryker Michael P. 
Published: January 2005

AbstractAnatomical and electrophysiological mapping techniques were used to determine topographic organization and arrangement of ocular dominance columns in the primary visual cortex of ferrets. From its border with area 18 on the posterior lateral gyrus, area 17 extends around the caudal pole of the hemisphere and over the splenial gyrus to the caudal bank of the splenial sulcus. The visuotopic map is oriented with the isoazimuth lines approximately parallel to the long axis of the posterior lateral gyrus and the isoelevation lines approximately perpendicular to the isoazimuths. Central azimuths are represented on the posterior lateral gyrus and peripheral azimuths are represented on the splenial gyrus; the inferior visual field maps medially and the superior visual field maps laterally. As in other species, the representation of the central visual field is expanded.The ferret has a considerable degree of binocular vision. Receptive fields driven through the ipsilateral eye extended more than 20° into the contralateral visual field. Within the region of area 17 corresponding to the binocular portion of the visual field, tritiated proline injected into one eye transneuronally labelled an ipsilateral projection as a series of patchy bands roughly complementary to gaps in the labelled contralateral projection. Physiological ocular dominance columns were evident as well in that neurons and groups of neurons recorded in this region showed clustered ocular dominance preferences. Most single neurons studied were binocularly driven.
Laminar histochemical and cytochemical localization of cytochrome oxidase in the goldfish retina and optic tectum in response to deafferentation and during regeneration
Authors: Kageyama Glenn H. , Meyer Ronald L. 
Published: January 2005

AbstractCytochrome oxidase (C.O.) histochemistry and cytochemistry were used to examine the effects of optic denervation and subsequent optic fiber regeneration on oxidative metabolism in the retina and optic tectum of the goldfish. In the tectum, there was a dramatic and rapid decrease in C.O. activity within the optic layers 3–4 days after contralateral eye removal or optic nerve crush. At the E.M. level this was correlated with an initial decrease in mitochondrial reactivity within optic terminals followed by the subsequent degradation of mitochondria and phagocytosis of optic terminals.By 1 month after optic nerve crush, the entire tectum was reinnervated. However, the normal dark reactivity of the stratum fibrosum et griseum superficialis (SFGS), the main optic innervation layer, was not restored until after 3–4 months postcrush. The normal intense reactivity of the largediameter optic axons and terminals at the bottom of the SFGS required an even longer period, about 7–8 months, for full recovery. The delayed restoration of C.O. reactivity was not due to a delay in synaptogenesis or in mitochondrial accumulation within optic terminals but to a delay in the maturation of mitochondrial reactivity. Following regeneration, the normal sublaminar stratification of C.O. bands was reestablished, suggesting that metabolically distinct classes of optic fibers may reinnervate at their original sublaminae. By using a distinct and persistent C.O. reactive sublamina, a of stratum griseum centrale (SGCa), just subjacent to the SFGS, it was possible to measure the thickness of the SFGS following optic denervation and subsequent reinnervation. At 1 week after optic nerve crush, the SFGS shrank by 35%. During regeneration, the thickness of the SFGS gradually increased to about 23% above normal at 2 months postcrush and this was maintained indefinitely.In the retina, ganglion cells were hypertrophic by 1 month postcrush and exhibited elevated levels of C.O. during the same period of time when optic terminals were unreactive. This indicates that oxidative metabolic activity within perikarya and axon terminals of the same neuron may be locally and independently regulated. It also suggests that in spite of the well‐known elevation of axonal transport during the initial period of axon elongation and synaptogenesis, that oxidative metabolic energy production within the optic fibers is less than that of the mature projection. We hypothesize that the comparatively greater oxidative metabolism of the mature projection results from greater synaptic convergence of fibers having correlated activity and may be a target‐mediated metabolic response of optic axons having reached their topographically appropriate synaptic sites.
Dense‐cored vesicle‐containing components of the terminal nerve of sharks and rays
Authors: Demski Leo S. , Fields R. Douglas 
Published: January 2005

AbstractThis paper describes electron microscopic observations of dense‐cored vesicle‐containing axons, cell bodies, and endings of the terminal nerve in several elasmobranchs. The vesicles are found in two apparent cell types, one with a polymorphic nucleus and another with an oval nucleus. The types may correspond to cells producing one each of two neuropeptides (LHRH and FMRF‐amide) that have previously been localized in the nerve. Dense‐cored vesicles are found in many unmyelinated fibers in both the terminal nerve proper and its major ganglia. Some of these form complicated structures with interdigitation and wrapping of membranes. Vesicle‐containing fibers branch from the nerve, run along nearby blood vessels, and appear to end adjacent to endothelial cells which demonstrate vesicular activity. The observations suggest terminal nerve neurosecretion into the cerebral circulation. Synapses are found in and near the ganglia where they appear to be axodendritic, with multiple contacts in some cases.
Correspondence between high affinity 125I‐neurotensin binding sites and dopaminergic neurons in the rat substantia nigra and ventral tegmental area: A combined radioautographic and immunohistochemical light microscopic study
Authors: Szigethy E. , Beaudet A. 
Published: January 2005

AbstractSeveral lines of anatomical, biochemical, and pharmacological evidence have suggested that specific high affinity neurotensin binding sites are associated with dopamine‐containing neurons in the rat ventral tegmentum. In the present study we confirmed and quantified the extent of this association by combining monoiodinated neurotensin radioautography and tyrosine hydroxylase immunohistochemistry on adjacent 5–10μm‐thick midbrain sections. We found that 95–100% tyrosine hydroxylase‐immunoreactive neurons detected in all subdivisions of the substantia nigra (pars compacta, pars lateralis, and pars reticulata) exhibited intense 125I‐neurotensin labeling in adjacent light microscopic radioautographs. Tyrosine hydroxylase‐positive dendrites radiating downward from compacta neurons were also heavily labeled throughout the pars reticulata. In the paranigral subdivision of the ventral tegmental area, silver grains were evenly distributed over neuropil and perikarya and therefore could not be readily attributed to any given tyrosine hydroxylase‐positive element. In contrast, within the parabrachial pigmentous subdivision of the ventral tegmental area, 80–90% of the tyrosine hydroxylase‐immunoreactive somata and proximal processes were clearly in register with 125I‐neurotensin labeled cells. Finally, all tightly packed TH‐positive neurons in the interfascicular nucleus showed intense 125I‐neurotensin labeling. The vast majority of the neurotensin binding sites observed in the ventral midbrain tegmentum were of the high affinity, physiologically active receptor type since levocabastine, a selective blocker of the low affinity neurotensin binding component, had minimal effect on the binding density in any of the midbrain regions examined. The present results demonstrate an extensive overlap between specific, high affinity neurotensin binding sites and dopamine perikarya and dendrites in the rat ventral tegmentum, and thereby provide a direct anatomical substrate for observed neurotensin‐dopamine interactions in the mesocorticolimbic and nigrostriatal projection systems.
Axonal connections of a forebrain nucleus involved with vocal learning in zebra finches
Authors: Bottjer Sarah W. , Halsema Keri A. , Brown Sandra A. , Miesner Elizabeth A. 
Published: January 2005

AbstractConnections of a telencephalic vocal‐control nucleus, the lateral magnocellular nucleus of the anterior neostriatum (lMAN), were studied in adult male zebra finches. Anterograde transport of horseradish peroxidase (alone or conjugated to wheat germ agglutinin) revealed that neurons in lMAN project to another forebrain song‐control nucleus, the robust nucleus of the archistriatum (RA). RA is known to project onto the hypoglossal motor neurons that innervate the vocal organ. Retrograde transport of HRP from lMAN labeled a large thalamic nucleus, the medial portion of the dorsolateral nucleus of the thalamus (DLM). DLM in turn receives input from another nucleus of the song‐control system, area X of the parolfactory lobe. We confirmed results of previous studies showing that area X receives a projection from the ventral area of Tsai (AVT) in the midbrain. In addition, we replicated results of previous experiments with canaries showing that the song‐control nucleus HVc (caudal nucleus of the ventral hyperstriatum) receives input from three sources: the medial magnocellular nucleus of the anterior neostriatum (mMAN), the interfacial nucleus (NIf), and the uvae‐form nucleus (Uva) of the thalamus. HVc neurons project to area X and to RA. In summary, there is a path from AVT in the midbrain, to area X, to DLM, and then to lMAN; HVc projects to X and hence indirectly to lMAN. We do not yet know the afferent connections of AVT. Thus, lMAN receives indirect input from a variety of other sources, including other regions known to be involved with vocal control.
Morphological types of spinomesencephalic neurons in the marginal zone (Lamina I) of the rat spinal cord, as shown after retrograde labelling with cholera toxin subunit B
Authors: Lima Deolinda , Coimbra Antonio 
Published: January 2005

AbstractRetrogradely labelled lamina I neurons were studied after intramesencephalic injections of subunit B of cholera toxin. The tracer was visualized with a mixture of two monoclonal antibodies followed by the peroxidase‐antiperoxidase technique that produced Golgi‐like staining of the labelled cells. A morphological and morphometric analysis in the three anatomical viewing planes disclosed two structural neuronal types which were recognized as the fusiform and pyramidal cells of our Golgi‐based classification of rat marginal cells. Fusiform cells had a bipolar longitudinally elongated dendritic arbor, were located in the lateral third of lamina I, and appeared to project mainly to the contralateral parabrachial nuclei. It is asserted that these cells may convey the spinal input which elicits visceral responses generated in that area. Pyramidal cells were longitudinally oriented pyramids with the triangular base straddling the dorsal horn/white matter border and a dendritic arbor extending lateromedially and mainly rostrocaudally throughout superficial lamina I and the dorsal funiculus. These cells occurred along the entire mediolateral extent of lamina I and seemed to have a prevalent projection to the contralateral caudal ventrolateral periaqueductal gray. They may represent the ascending branch of the spinalmidbrain loop centered in that zone which controls nociceptive transmission postsynaptically in the dorsal horn.
Forebrain projections from cholecystokininlike‐immunoreactive neurons in the rat midbrain
Authors: Seroogy Kim B. , Fallon James H. 
Published: January 2005

AbstractThe purpose of the present study was to analyze the distribution of cholecystokininlike‐immunoreactive (CCK‐I) neurons within the rat ventral mesencephalon which project to several forebrain areas. The peroxidase‐antiperoxidase immunocytochemical technique was used to examine the anatomical localization of CCK‐I within the ventral midbrain and in the following forebrain regions: caudate‐putamen, nucleus accumbens, olfactory tubercle, bed nucleus of the stria terminalis, septum, amygdala, and prefrontal, anterior cingulate, and piriform cortices. CCK‐I perikarya were distributed throughout the substantia nigra, ventral tegmental area, and several midline raphe nuclei to a greater extent than previously reported, particularly in the substantia nigra pars compacta. Terminallike immunoreactivity for CCK was observed in all of the above forebrain sites. In addition, infrequent CCK‐I cell bodies were localized in the caudate‐putamen, nucleus accumbens, olfactory tubercle, septum, and bed nucleus of the stria terminalis.To analyze forebrain projections of the ventral midbrain CCK‐I neurons, indirect immunofluorescence was combined with fluorescence retrograde tracing. CCK‐I neurons of the substantia nigra and/or ventral tegmental area were found to project, to varying extents, to all of the above CCK‐I forebrain terminal fields. The nucleus accumbens, olfactory tubercle, and septal and prefrontal cortical projections arose primarily from CCK‐I perikarya in the ventral tegmental area whereas the projections to the caudateputamen and anterior cingulate cortex arose predominantly from immunoreactive neurons in the substantia nigra pars compacta. The amygdala received innervation mainly from CCK‐I cell bodies located in the substantia nigra pars lateralis. CCK‐I afferents to the bed nucleus of the stria terminalis and piriform cortex originated from perikarya distributed approximately equally across the ventral tegmental area and substantia nigra pars compacta. The general topography of CCK‐I forebrain innervation observed in this study is similar to that previously reported for the ascending dopaminergic projections from ventral mesencephalic neurons. CCK‐I neurons of the midline raphe nuclei were found to provide relatively minor afferents to the caudate‐putamen, bed nucleus of the stria terminalis, septum, and prefrontal cortex and more substantial projections to the amygdala.The results of this study demonstrate that CCK‐I neurons of the ventral midbrain supply a much broader innervation of forebrain regions than previously appreciated. Moreover, these data suggest that ventral mesencephalic CCK projections encompass the full range of the well‐known dopaminergic masolimbic. mesostriatal, and mesocortial projections. Thus, CCK may play a significant role in the ascending mesotelencephalic systems.
Comparison of met‐enkephalin, dynorphin a, and neurotensin immunoreactive neurons in the cat and rat spinal cords: II. Segmental differences in the marginal zone
Authors: Miller Kenneth E. , Seybold Virginia S. 
Published: January 2005

AbstractThis study examined the number of met‐enkephalin, dynorphin A 1–8, and neurotensin immunoreactive (IR) neurons in the marginal zone (lamina I) at one thoracic (T8:cat,T9:rat), one midlumbar (L5:cat,L4:rat), and one lower lumbar or sacral (S1:cat,L6:rat) spinal cord segment in the cat and rat. Marginal zone IR neurons ranged 10–70 μm in diameter in cats and 10–50 μm in rats and were flattened, pyramidal, fusiform, or polygonal in morphology. Immunoreactive neurons for each peptide in both species were found in the marginal zone at all spinal levels, but with a differential segmental distribution. The average number of IR neurons per 50‐:μm section generally was lowest in thoracic cord and greatest in lower lumbar/sacral cord for all peptides. For enkephalin and dynorphin, the estimated total number of IR neurons per segment and number of IR neurons per volume (mm3) generally were lowest in the midlumbar segments and highest in the thoracic and lower lumbar/sacral cord. For neurotensin, the estimated total number of neurons per segment remained lowest in the thoracic and largest in the lower lumbar/sacral cord. The number of neurotensin IR neurons per volume was equal in the thoracic and midlumbar cord, but remained highest at lower lumbar/sacral levels. The IR neurons quantified in this study may be interneurons or may serve as supraspinal projection neurons. The large number of IR neurons observed in segments receiving a relatively large visceral afferent input suggests that some of these neurons may be involved in visceral sensory processing. In addition, the segmental distribution of the IR neurons indicates that physiological and pharmacological studies on the effects of opioid and/or neurotensin peptides should be interpreted in light of the spinal segment(s) investigated.