bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prenatal development of GABA‐ergic neurons in the neocortex of the rat
Authors: van Eden C. G. , Mrzljak L. , Voorn P. , Uylings H. B. M. 
Published: January 2005

AbstractThe present study shows that in the prenatal rat neocortex the GABA immunoreactive neurons are not limited to the marginal, subplate, and intermediate zones, but are also found in all fetal zones of the cerebral anlage. The first GABA‐ergic cells are observed on embryonic day 14 in the plexiform primordium. On embryonic day 15, a second population of GABA‐ergic cells is observed in the intermediate zone. Beginning on day 16 of gestation and continuing throughout gestation, GABA‐ergic neurons are observed in the marginal zone, the subplate zone, the cortical plate, and the ventricular and subventricular zones. Furthermore, while the number of GABA‐ergic cells in the cortical plate increases, GABA‐ergic neurons in the intermediate zone and subventricular zone decrease in number after embryonic day 19.
Regional differences in the distribution of muscarinic cholinergic receptors in the macaque cerebral cortex
Authors: Lidow Michael S. , Gallager Dorothy W. , Rakic Pasko , Goldman‐Rakic Patricia S. 
Published: January 2005

AbstractThe in vitro autoradiographic technique was used to characterize the density and laminar distribution of muscarinic cholinergic receptors in 12 cytoarchitectonic areas in the frontal, parietal, and occipital lobes of the rhesus monkey. The entire population of muscarinic receptors was labeled with [3H]quinuclidinyl‐benzilate; the M1 receptor subtype was labeled with [3H]pirenzepine; and the density of the M2 receptor subtype was estimated by subtracting the density of M1 receptors from the total population. The overall density of M1 and M2 receptor subtypes was similar throughout the cerebral cortex. However, their laminar distribution varied regionally. In cortical regions of the parietal and occipital lobes and in the primary motor cortex of the frontal lobe, both M1 and M2 receptor subtypes were concentrated in the supragranular layers. By contrast, in prefrontal cortical areas, the combined population of M1 and M2 receptors was evenly distributed across the cortical layers, though M1 receptors were most dense and M2 receptors least dense in layer IV. The difference in the distribution of cholinergic receptors in the prefrontal cortex compared to other neocortical areas reveals a degree of chemoarchitectural specificity of this region with respect to cholinergic markers that has escaped immunohistochemical and other anatomical and functional techniques.
Regeneration of the neurohemal terminals for identified cerebral neurosecretory cells in an insect
Authors: Agui Noriaki , Westbrook Anne L. , McQueen Chapman T. , Flanagan Thomas R. , Bollenbacher Walter E. 
Published: January 2005

AbstractThe axons of specific neurosecretory cells, L‐NSC III, in the brain of the tobacco hornworm, Manduca sexta, were transected during larval‐pupal development to study the effects of this type of lesion on these peptidergic neurons and to begin to identify factors that may regulate their regeneration and growth. The two somata of these bilaterally paired neurons produce the prothoracicotropic hormone and are located in the pars intercerebralis. Their axons exit from the contralateral brain lobe via a retrocerebral nerve and pass through the corpus cardiacum before terminating at the glandular corpus allatum. At the corpus allatum, the L‐NSC III axons arborize to form the terminal neurohemal organ for prothoracicotropic hormone release. The retrocerebral nerve was severed either in vitro followed by brain transplantation or in situ; in either protocol, the distal axon segments and corpus allatum were removed. The ability of the injured L‐NSC III axons to regenerate was assessed immunocytologically by using a monoclonal antibody against the prothoracicotropic hormone. In both treatments, the proximal axon stumps exhibited regenerative growth as early as 1 day after axotomy, and, by the third day, neurites had extended. By the fifth day, the regenerating axons had branched to form terminal varicosities similar to those of a normal neurohemal organ. The regenerated neurohemal structure appeared to be functional, because larvae that had been bilaterally axotomized were able to metamorphose to pupae, a process requiring temporally precise periods of prothoracicotropic hormone release. In addition to the regeneration of the terminal axon structures, several other responses to axotomy and retrocerebral organ excision occurred. These included an apparent accumulation of prothoracicotropic hormone in the axons and regenerating neurohemal‐like structures, sprouting of ectopic neurites from the axotomized somata, and a change in shape of the cell bodies from spherical to ovoid.
Glucose‐6‐phosphate dehydrogenase activity in the olfactory system of the young rat: An enzyme histochemical study using computerized image analysis
Authors: Coopersmith Robert , Leon Michael 
Published: January 2005

AbstractAn understanding of olfactory system glucose metabolism is necessary for the interpretation of radiolabeled 2‐deoxyglucose studies of odor processing since the relationship between glucose uptake and neural activity is based on assumptions regarding cellular glucose utilization. As part of an ongoing study examining divergent pathways of glucose metabolism in the olfactory system, the relative activity of glucose‐6‐phosphate dehydrogenase, the rate‐limiting enzyme of the hexose monophosphate shunt, was examined among cells of the rat olfactory bulb and anterior olfactory nucleus, by using enzyme histochemistry on fresh frozen tissue. Optical density measurements of formazan reaction product in stained tissue were quantified by computerized image analysis. To aid in the identification of histochemically stained neurons, alternate sections were Nissl‐stained. The highest olfactory bulb dehydrogenase levels were found in the olfactory nerve and glomerular layers. Individual mitral and tufted cells also showed high dehydrogenase activity. In most stained neurons, formazan reaction product filled the cytoplasm and sometimes extended into the proximal part of dendrites and axons. The external plexiform and granule cell layers had low enzyme activity. High activity also was seen in pyramidal cells of pars dorsalis and pars lateralis of the anterior olfactory nucleus, one of the first, and most rostral of the olfactory bulb projection sites. High glucose‐6‐phosphate dehydrogenase activity in the olfactory system indicates that a significant amount of glucose can be channeled through the hexose monophosphate shunt in these neurons, with a concomitant production of NADPH. This may reflect high activity of cellular detoxification enzymes that rely on NADPH for reducing power. Such detoxification processes may be engaged in response to the potential entry and transsynaptic movement of airborne chemicals into the brain via the olfactory system.
Distribution of uncrossed axons along the course of the optic nerve and chiasm of rodents
Authors: Baker G. E. , Jeffery Glen 
Published: January 2005

AbstractThe distribution of the ipsilaterally projecting population of retinofugal axons has been analyzed following injections of horseradish peroxidase (HRP) into the optic tract of adult hamsters and rats to determine whether the topographical segregation of the cells of origin seen in the retina is maintained by their axons throughout the course of the optic nerve and chiasm.Axons are limited to a roughly appropriate topographic location within the intraorbital course of the nerve but this organization changes at levels progressively closer to the optic chiasm. Immediately rostral to the chiasm labelled profiles are found dispersed across most of the cross‐sectional area of the nerve. This dispersal is maintained within the region of the optic chiasm where a complex rearrangement of ipsilaterally projecting axons takes place.The results show that axons are not retinotopically organized along the entire length of the optic nerve. The order of axons changes along the course of the nerve and in the optic chiasm. The change seen within the intracranial course may indicate a chronotopic re‐sorting of axons prior to the optic tract where the organization of axons has previously been interpretted as a map of time of axon arrival.
Interrelationship of the distribution of neuropeptides and tyrosine hydroxylase immunoreactivity in the human substantia nigra
Authors: Haber S. N. , Groenewegen H. J. 
Published: January 2005

AbstractThe relationship in the human substantia nigra of peptidergic fibers with intrinsic dopaminergic neurons was studied in adjacent coronal sections of the mesencephalon immunohistochemically stained for enkephalin (ENK), substance P (SP), and tyrosine (TH) hydroxylase immunoreactivity. TH‐positive elements are present in the substantia nigra in at least two different arrangements: (1) a dorsal tier of rather loosely arranged neurons, which is continuous medially with the ventral tegmental area and laterally with the retrorubral area, (2) a ventral tier of more closely packed neurons, clusters of which frequently form finger‐like extensions deep into the pars reticulata. This ventral region contains TH‐positive dendrites extending ventrally into the pars reticulata.The distribution of ENK is mainly restricted to the medial half of the ventral aspect of the substantia nigra, while SP occupies its entire rostral‐caudal and medial‐lateral extents. Peptide‐positive fibers vary in density from dense to light. There is very little overlap between the dorsal tier of the TH‐positive neurons and the ENK or SP staining. The dorsal part of the peptide‐immunoreactive area extensively overlaps with the TH‐positive neurons of the ventral tier of cells. The ventral part of the peptide‐positive area overlaps with the pars reticulata of the substantia nigra in which the TH‐positive dendrites extend.The overlap between the neuropeptide fibers and the TH‐positive cells of the ventral tier is not complete, with cells found both within and outside peptide‐positive fiber networks. Three patterns of overlap emerge. In dorsal regions elongated cell clusters lie partially within and partially outside the dense peptide‐positive fiber networks. In the ventral regions TH‐positive cells are either completely embedded within peptide fibers or clusters of cells are present in peptide‐free zones.These data suggest that specific peptidergic pathways differentially innervate the substantia nigra. TH cells which lie within or outside these fibers may reflect functionally different subsystems in the striatonigral pathways in the human.
Fate of descending interneurons in the metamorphosing brain of an insect, the beetle Tenebrio molitor L
Authors: Breidbach Olaf 
Published: January 2005

AbstractThe fate of descending brain‐thoracic neurons in the metamorphosing supraoesophageal ganglion of the mealworm beetle, Tenebrio molitor, is described. Comparison of the descending neurons of the larval, various pupal, and adult stages outlines a high degree of topological invariance in the structure of descending interneurons; i.e., the basic organization of the imaginal set of descending neurons is anticipated by the structure of the larval neurons. Single descending neurons of analogous clusters of larval and imaginal neurons outline a virtual identical structural organization in both the larval and imaginal brain.There is a quantitative increase from approximately 70 to approximately 120 brain‐thoracic interneurons during metamorphosis. This increase does not cause complex transformations in the structural organization of the descending interneurons. Experiments with the DNA‐inhibitor hydroxyurea prove that the described topological invariant structure of the set of descending neurons is based on the persistence of individually descending neurons. There is evidence that the whole set of larval interneurons persists throughout the beetles' metamorphosis.The essential characteristics of the later imaginal set of descending neurons are qualitatively and quantitatively established within the first 10% of pupation. Structural invariance of the set of descending neurons is discussed with regard to the significance of cellular interaction for the mechanisms of metamorphic reorganization of nervous tissue.
Comparative immunocytochemical study of the catecholaminergic and peptidergic afferent innervation to the dorsal vagal complex in rat and guinea pig
Authors: Siaud P. , Denoroy L. , Assenmacher I. , Alonso G. 
Published: January 2005

AbstractLight and electron microscopic immunocytochemistry was used to study the fine structural organization of the catecholaminergic and hypothalamic peptidergic innervation of the dorsal vagal complex of the medulla oblongata in the rat and guinea pig, the latter of which is known to lack central adrenergic neurons. In the rat, adrenergic fibers immunoreactive to phenylethanolamine‐N‐methyltransferase were concentrated in the dorsal motor nucleus of the vagus, where they established frequent symmetric synapses with dendrites and perikarya. On the other hand, the density of both oxytocin‐ and corticotropin‐immunoreactive fibers appeared far lower in this nucleus than in the dorsal regions of the nucleus of the tractus solitarius, where they formed asymmetric synapses with small dendrites. In tissue treated for the dual labeling of two neuronal antigens, oxytocin‐ or corticotropin‐reactive fibers were in close contact with adrenergic neurons in this dorsal medullary region. In the guinea pig, unlike the rat, the dorsal motor nucleus of the vagus contained large amounts of oxytocin‐ and corticotropin‐reactive fibers, which formed many symmetric synapses with perikarya and dendrites. Taken together, these data suggest that the control of vagal preganglionic neurons by hypothalamic peptidergic neurons involves a bisynaptic neuronal pathway including adrenergic medullary neurons in the rat, whereas it is direct in the guinea pig, which lacks this adrenergic relay.
Ascending unmyelinated primary afferent fibers in the dorsal funiculus
Authors: Patterson J. T. , Head P. A. , McNeill D. L. , Chung K. , Coggeshall R. E. 
Published: January 2005

AbstractThe primary purpose of the present study is to obtain evidence as to the destination of the recently discovered unmyelinated primary afferent fibers in the mammalian dorsal funiculus. To do this rat dorsal roots were transected unilaterally from segments T8 or T9 caudally, and the numbers of axons were determined in the C3 fasciculus gracilis in normal animals and from both sides of the rhizotomied animals. In addition, C3 fasciculus gracilis counts were done in animals that had complete T6 or T10 spinal transections. The data indicate that there is an 80% loss of unmyelinated axons ipsilaterally and a 60% loss contralaterally in the fasciculus gracilis of the rhizotomied animals. These findings are interpreted as indicating that a significant fraction of the unmyelinated fibers in the fasciculus gracilis ascend, presumably to the nucleus gracilis in the brain stem, and also that a significant number of these fibers branch. We also provide evidence for contralateral myelinated primary afferent fiber projection in the fasciculus gracilis and show that the myelinated primary afferent fibers seem to be a more diverse population than the unmyelinated primary afferent fibers in the C3 fasciculus gracilis.
Cytoarchitecture of the tectum mesencephali in salamanders: A golgi and HRP study
Authors: Roth Gerhard , Naujoks‐Manteuffel Christiane , Grunwald Wolfgang 
Published: January 2005

AbstractThe tectum mesencephali of salamanders shows a morphology that has long been considered primitive when compared with that of frogs. The alternative hypothesis is that the salamander brain is secondarily simplified. In order to test these two hypotheses, the cytoarchitecture of the tectum and the projections of tectal neurons were studied in 11 species of salamanders. Application of the Golgi method reveals three major morphological types. Type 1 has a very wide dendritic arborization mostly confined to the deep fiber layers, and somata are always located within the most superficial part of the periventricular gray matter. Type 2 possesses a wide to medium‐size dendritic arborization. In subtype 2a the somata are located in the uppermost part of the gray, and dendrites always reach the uppermost layer of retinal afferents; in subtype 2b the somata are found in deeper parts of the gray, and dendrites arborize in the deeper layers of retinal afferents; and in subtype 2c the somata are also located in deeper parts, but the wide dendritic arborization is confined to deep fiber layers. Type 3 shows the narrowest dendritic arbors that always reach the upper two tectal fiber layers. The somata are found at any depth of the gray matter.HRP experiments reveal a correlation between morphological differences and the projections of tectal neurons. Type 1‐ and type 2c‐like cells constitute the uncrossed tecto‐bulbo‐spinal tract, whereas type 1‐ and type 2a‐like cells and migrated large spindle‐shaped cells (Salamandra) constitute the crossed tecto‐bulbo‐spinal tract. Type 3‐like neurons project to thalamic, pretectal and isthmc termination sites.The HRP experiments also demonstrate the existence of two classes of mesencephalic trigeminal cells.A comparison shows that salamanders and frogs possess very similar functional and morphological types of tectal cells. However, tectal cells of salamanders show a “juvenile” morphology, and the number of migrated cells is about 10 times higher in frogs compared to salamanders. Both phenomena are seen as the result of secondary simplification of brain structures in the context of paedomorphosis.
Variation and symmetry in the lumbar and thoracic dorsal root ganglion cell populations of newly metamorphosed xenopus laevis
Authors: Sperry David G. 
Published: January 2005

AbstractThe size of the lumbar and thoracic dorsal root ganglion cell populations in normally developing newly metamorphosed Xenopus laevis were measured in order to determine whether these neuron populations have the same characteristics as the hindlimb motoneuron population; i. e., large individual as well as sibling group differences, striking bilateral symmetry, and a rough correspondence between neuron number and body size that suggests some peripheral control of cell number during normal development (Sperry, J. Comp. Neurol. 264:250‐267). Among animals from three sibling groups, the total numbers of thoracic and lumbar ganglion cells are highly variable and symmetrical, although symmetry is not uniformly present at the level of individual ganglion pairs. Significant sibling group differences in neuron number are also present. Metamorphic body size and cell number in the thoracic but not in the lumbar ganglia are significantly correlated. The motoneurons innervating the hindlimbs were also counted and measured in the same animals. While variable as well as symmetrical, motoneuron number and metamorphic body size are correlated in only two of the three sibling groups. Interestingly, the numbers of motoneurons and lumbar ganglion cells, two populations of neurons whose sizes one might predict would be significantly correlated in normally developing animals, are not correlated. The relationship between these observations and currently held views concerning how neuron numbers might be controlled during normal development is discussed.
Müller cells in adult rabbit retinae: Morphology, distribution and implications for function and development
Authors: Robinson Stephen R. , Dreher Zofia 
Published: January 2005

AbstractWe describe the morphology and distribution of Müller cells in wholemounts of rabbit retinae labelled with either monoclonal antibodies (anti‐Vimentin, 3H3, 4D6, and 4H11), or intracellular horseradish peroxidase. Several new features of Müller cell organization are noted. First, Müller cells appear to compose a single morphological class and their morphology varies systematically with retinal thickness. Second, in contrast to other retinal glia, Müller cells have a neuronlike distribution, with a peak density of 10,700–15,000 cells per 2 at the visual streak and a minimum density of 4,400–6,000 per mm2 at both the superior and inferior retinal edges. There are 4.2 ± 0.5 × 106 Müller cells per retina. Third, unlike in other species, rabbit Müller cells do not contact blood vessels, suggesting that they do not participate in the transfer of metabolites or in the blood:retinal barrier. Fourth, each Müller cell has a vitread endfoot about 20–40 μm in diameter composed of numerous fimbriae. The fimbriae from a single Müller cell generally contact several axon fascicles in the nerve fibre layer, and at each point along its length each fascicle is enclosed by the overlapping fimbriae from several Müller cells. Fifth, in the inner and outer plexiform layers, numerous filamentous branchlets extend 20 μm or more from the radial trunk, interweaving with branchlets from nearby Müller cells to form dense and continuous strata. In the ganglion cell layer and outer nuclear layer, Müller cell processes completely wrap neuronal somata, whereas in the inner nuclear layer they partially wrap somata. We discuss the functional and developmental implications of these observations.
Morphological organization of thalamocortical relay cells in the dorsal lateral geniculate nucleus of the north american opossum
Authors: Condo George J. , Wilson Paul D. 
Published: January 2005

AbstractThe morphology of relay cells in the dorsal lateral geniculate nucleus of the North American opossum was studied by using both Golgi‐Cox material and cells stained from retrograde transport of horseradish peroxidase. In general, soma sizes were largest in the part of the nucleus representing the central retina and decreased from the middle third of the nucleus to the anterior to posterior poles. Relay cells labeled with horseradish peroxidase were found to constitute approximately 90% of the dorsal lateral geniculate nucleus cells and have larger soma diameters than most unlabeled cells. From morphometric analysis of several structural characteristics, three classes of relay cells were identified in both Golgi‐Cox and horseradish peroxidase material. Type 1 cells, the predominant class, exhibited radially arranged primary dendritic fields, symmetrically organized relative to projection lines. Type 2 cells had relatively few primary dendrites, and complex dendritic fields that were oriented parallel to projection lines. Least numerous were Type 3 cells, which were characterized by relatively sparse dendritic fields oriented perpendicular to projection lines. An additional class of neuron, Type 4 cells, with small somata and sparse dendritic branching, was found only in Golgi‐Cox material. Cells with Type 4 dendritic morphology were not found with retrograde horse‐radish peroxidase labeling and may represent interneurons. The classification of morphologically characterized cells in the opossum dorsal lateral geniculate nucleus was evaluated quantitatively with multivariate discriminant analysis. The classes are compared to physiologically identified Y‐, X‐, and W‐like relay cells in the opossum and to relay cell classes in other species.