bluuebunny/crossref_metadata_2025_split huggingface dataset:
Specificity of corticospinal axon arbors sprouting into denervated contralateral spinal cord
Authors: Kuang Rong Zhen , Kalil Katherine 
Published: January 2005

AbstractPrevious studies have reported considerable plasticity in the rodent corticospinal pathway in response to injury. This includes sprouting of intact axons from the normal pathway into the contralateral spinal cord denervated by an early corticospinal lesion. We carried out the present study to obtain detailed information about the time course, origin, and degree of specificity of corticospinal axons sprouting in response to denervation. Hamsters (Mesocricetus auratus) ranging in age from 5 to 23 days received unilateral lesions of the left medullary pyramidal tract. Two weeks after the lesion, small regions of the right sensorimotor cortex opposite the lesion were injected with the plant lectin Phaseolus vulgaris leucoagglutinin (PHA‐L). After a further 2 week survival period, immunohistochemistry was carried out on frozen sections of the fixed brains and spinal cords. Detailed morphological analysis of PHA‐L labeled corticospinal axons revealed that sprouting from the intact corticospinal pathway into the contralateral denervated spinal cord occurred only at local spinal levels and not at the pyramidal decussation. Arbors sprouting into the denervated cord frequently arose from corticospinal axons that branched into the normal side of the cord as well. Sprouting was maximal after early lesions (5 days) and declined with lesions at later ages up to 19 days. Sprouting corticospinal axons arborized with the same degree of functional and topographic specificity as previously reported for normal corticospinal arbors (Kuang and Kalil: J. Comp. Neurol. 292:585–598, '90), such that axons arising from somatosensory cortex projected only to the dorsal horn, those from motor cortex innervated only the ventral horn, and normal forelimb and hindlimb topography was preserved. Sprouting fibers also had normal branching patterns. Parallel studies of developing corticospinal arbors showed that sprouting could not be attributed to maintenance or expansion of early bilateral connections. These results suggest that local signals, most likely similar to those governing normal corticospinal development, elicit corticospinal sprouting and determine specificity of axon arbors.
Thymic innervation in the rat: A light and electron microscopical study
Authors: Novotny G. E. K. , Sommerfeld H. , Zirbes T. 
Published: January 2005

AbstractThe innervation of the rat thymus was studied by light and electron microscopy in juvenile and aged rats. By light microscopy numerous fine nerves were found in the connective tissue septa penetrating between the thymic lobules. These septa were clearly delineated in the juvenile animals, but indistinct in the aged rats, thus creating the spurious impression that thymic parenchyma contains nerves. In the aged animals the nerves are thicker, tortuous, and more branched than in juvenile animals.Electron microscopy confirms the light microscopic observations: no nerves were found within the thymic parenchyma. The thymic capsule and larger connective tissue septa contain bundles of myelinated and unmyelinated axons, surrounded by a perineural sheath. Within the extraparenchymal compartment, which is greatly enlarged in aged animals, efferent and sensory nerves, devoid of perineurium, were found to contact mainly reticular cells, and in rare instances plasma cells and lymphocytes. The majority of axonal varicosities are not closely related to cellular elements, and, in general, vesicles are relatively infrequent. The possible functional significance of these observations is discussed.
Location of motor pools innervating chick wing
Authors: Hollyday Margaret , Jacobson Richard D. 
Published: January 2005

AbstractIntramuscular injections of HRP were used to map the spinal cord location of motoneurons innervating wing and shoulder girdle muscles in newly hatched chicks. Motor pools are grouped in the lateral motor column in relationship to embryonic origin of the muscles: muscles derived from the ventral muscle mass are innervated by medially lying motor pools, while muscles derived from the dorsal mass are innervated by lateral pools. Motor pool position is also well correlated with nerve supply. Muscles innervated by nerves diverging from common nerve trunks are innervated by neighboring motor pools. The rostro‐caudal organization of the motor pools reflects both proximo‐distal and antero‐posterior axes of the limb with proximal and anterior muscles innervated from rostral motor pools.
Sources of presumptive glutamatergic/aspartatergic afferents to the magnocellular basal forebrain in the rat
Authors: Carnes Kenneth M. , Fuller Terry A. , Price Joseph L. 
Published: January 2005

AbstractThe distribution of presumptive glutamatergic and/or aspartatergic neurons retrogradely labeled following injections of [3H]‐D‐aspartate into the magnocellular basal forebrain of the rat was compared with the distribution of neurons labeled by comparable injections of the nonspecific retrograde axonal tracer wheat germ agglutinin conjugated to horseradish peroxidase.Cells retrogradely labeled by wheat germ agglutinin‐horseradish peroxidase were found in a wide range of limbic and limbic‐related structures in the forebrain and brainstem. In the telencephalon, labeled neurons were seen in the orbital, medial prefrontal, and agranular insular cortical areas, the amygdaloid complex, and the hippocampal formation. Labeled cells were also seen in the olfactory cortex, the lateral septum, the ventral striatopallidal region, and the magnocellular basal forebrain itself. In the diencephalon, neurons were labeled in the midline nuclear complex of the thalamus, the lateral habenular nucleus, and the hypothalamus. In the brainstem, labeled cells were found bilaterally in the ventral midbrain, the central gray, the reticular formation, the parabrachial nuclei, the raphe nuclei, the laterodorsal tegmental nucleus, and the locus coeruleus.A significant fraction of the afferents to the magnocellular basal forebrain appear to be glutamatergic and/or aspartatergic. Only a few of the regions labeled with wheat germ agglutinin‐horseradish peroxidase were not also labeled with [3H]‐D‐aspartate in the comparable experiments. Most prominent among the non‐glutamatergic/aspartatergic projections were those from fields CA1 and CA3 of the hippocampus, the hilus of the dentate gyrus, the dorsal subiculum, the tuberomammillary nucleus, and the ventral pallidum. In addition, most of the lateral hypothalamic and brainstem projections to the magnocellular basal forebrain were not significantly labeled with [3H]‐D‐aspartate.In addition to these inputs, a commissural projection from the region of the contralateral nucleus of the horizontal limb of the diagonal band was confirmed with both wheat germ agglutinin‐horseradish peroxidase and the anterograde axonal tracer Phaseolus vulgaris leucoagglutinin. This projection did not label with [3H]‐D‐aspartate or [3H]‐GABA, suggesting that it is not glutamatergic/aspartatergic or GABAergic. Furthermore, double labeling experiments with the fluorescent retrograde tracer True Blue and antibodies against choline acetyltransferase indicate that the projection is not cholinergic.
Transcellular labeling of taste bud cells by carbocyanine dye (diI) applied to peripheral nerves in the barbels of the catfish, Ictalurus punctatus
Authors: Finger Thomas E. , Böttger Bärbel 
Published: January 2005

AbstractIn order to study the pattern of innervation of taste buds and the surrounding epithelium, the carbocyanine dye diI was applied to the nerve stump in isolated, paraformaldehyde‐fixed barbels obtained from channel catfish, Ictalurus punctatus. After a diffusion period of 7–41 days, the barbels were sectioned on a vibratome and examined with epifluorescence. Labeled axons were observed up to 1 cm from the site of application. Frequently, a fascicle of labeled axons turned outward toward the epithelium to innervate taste buds or to end apparently as free endings within the epithelium. Within 2–3 mm of the dye‐application site, many taste buds contained one or at most 5–10, labeled spindle‐shaped, presumed receptor, cells. In taste buds containing multiple labeled cells, the cells usually were arranged as intertwined pairs or triplets rather than being homogeneously distributed within the taste bud. In a few cases, labeled basal cells could be discerned among the labeled axons of the basal plexus. The cells of the taste bud apparently were labeled by transcellular passage of the dye from the nerve fibers into the cells. The limited number of labeled cells within each taste bud may indicate a special relationship between these cells and the nerve fibers innervating them.
Descending neurons supplying the neck and flight motor of diptera: Physiological and anatomical characteristics
Authors: Gronenberg Wulfila , Strausfeld Nicholas J. 
Published: January 2005

AbstractIn Diptera, dorsal neuropils of the pro‐, meso‐, and metathoracic ganglia supply motor neurons to neck and flight muscles. Motor circuits are supplied by more than 50 pairs of descending neurons (DNs) whose dendritic trees in the brain are restricted to dorsal neuropils of the deutocerebrum where they are grouped together into discrete clusters. Each cluster is visited by wide‐field motion‐sensitive neurons and by morphologically small‐field retinotopic elements. This organization suggests that flight descending neurons should respond to complex stimuli reflecting panoramic movement and small‐field motion. Intracellular recordings, combined with dye filling, confirm this. Certain descending neurons responding to visual flow fields terminate bilaterally in superficial pterothoracic neuropils, at the level of indirect (power) flight muscle motor neurons. Other DNs terminate laterally, and provide segmental collaterals to areas containing neck and direct (steering) flight muscle motor neurons. Such DNs are activated by wide‐field directional stimuli corresponding to pitch, roll, or yaw, and to small‐field stimuli. Appropriate directional mechanosensory stimuli also activate dorsal descending neurons. The significance of dorsal descending neurons for the control of flight is discussed and compared with studies on course deviation neurons in other insects. It is suggested that, in Diptera, dorsal descending neurons may separately be involved in the control of velocity, stabilization, and steering manoeuvres.
Dietary sodium chloride deprivation throughout development selectively influences the terminal field organization of gustatory afferent fibers projecting to the rat nucleus of the solitary tract
Authors: King Camille Tessitore , Hill David L. 
Published: January 2005

AbstractIn order to determine whether the developing central gustatory system responds to altered sensory experience, terminal fields of the chorda tympani nerve (CT) within the nucleus of the solitary tract (NTS) in control, NaCl deprived, and rats in which CT taste responses “recovered” from NaCl deprivation were investigated via anterograde transport of HRP. Rats fed a low sodium diet (0.03% NaCl) from the third day of gestation to at least 35 days postnatal exhibited both abnormally distributed and irregularly shaped CT terminal fields. Specifically, the dorsal zone of the field was the smallest in controls whereas it was the largest in deprived rats, occupying more medial and caudal territory within the nucleus. The portion of the field immediately ventral to the dorsalmost zone was characterized by a compact, oval shape in control rats and an irregular, broad configuration in deprived rats. Although it has been observed that deprivation‐induced changes in the neurophysiology of the CT are reversible, the central morphological alterations reported here remain abnormal. Restoration of 1.0% NaCl in the diet at 28 days postnatally, for at least 60 days, did not result in normal CT terminal fields. The pattern of the field in rats “recovered” from NaCl deprivation was comparable to that found in deprived rats, and the size of the field was three times that found in control and deprived rats.The terminal fields of another nerve containing gustatory afferents, the lingual‐tonsilar branch of the glossopharyngeal nerve (LT‐IX), were studied for comparison. Interestingly, the pattern of the LT‐IX field was not altered by sodium deprivation. The relative size and topography of the LT‐IX fields in deprived rats were similar to controls. Thus, sodium deprivation appears to alter selectively the anatomical organization of the CT. Differences in vulnerability between the CT and LT‐IX terminal fields may derive from differences in the responsiveness of these nerves to NaCl, and/or to differences in the timing of early neural events.
Synaptic organization of projections from basal forebrain structures to the mediodorsal thalamic nucleus of the rat
Authors: Kuroda Masaru , Price Joseph L. 
Published: January 2005

AbstractThe synaptic organization of the mediodorsal thalamic nucleus (MD) in the rat was studied with the electron microscope, and correlated with the termination of afferent fibers labeled with wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP). Presynaptic axon terminals were classified into four categories in MD on the basis of the size, synaptic vesicle morphology, and synaptic membrane specializations: (1) small axon terminals with round synaptic vesicles (SR), which made asymmetrical synaptic contacts predominantly with small dendritic shafts; (2) large axon terminals with round vesicles (LR), which established asymmetrical synaptic junctions mainly with large dendritic shafts; (3) small to medium axon terminals with pleomorphic vesicles (SMP), which formed symmetrical synaptic contacts with somata and small‐diameter dendrites; (4) large axon terminals with pleomorphic vesicles (LP), which made symmetrical synaptic contacts with large dendritic shafts. Synaptic glomeruli were also identified in MD that contained either LR or LP terminals as the central presynaptic components. No presynaptic dendrites were identified.In order to identify terminals arising from different sources, injections of WGA‐HRP were made into cortical and subcortical structures known to project to MD, including the prefrontal cortex, piriform cortex, amygdala, ventral pallidum and thalamic reticular nucleus. Axons from the amygdala formed LR terminals, while those from the prefrontal and insular cortex ended exclusively in SR terminals. Fibers labeled from tie piriform cortex formed both LR and SR endings. Based on their morphology, all of these are presumed to be excitatory. In contrast, the axons from the ventral pallidum ended as LP terminals, and those from the thalamic reticular nucleus formed SMP terminals. Both are presumed to be inhibitory. At least some terminals from these sources have also been identified as GABAergic, based on double labeling with anterogradely transported WGA‐HRP and glutamic acid decarboxylase (GAD) immunocytochemistry.
Identifiable reticulospinal neurons of the adult zebrafish, Brachydanio rerio
Authors: K. Lee Robert K. , Eaton Robert C. 
Published: January 2005

AbstractReticulospinal neurons of the larval zebrafish Brachydanio rerio have been categorized into 27 different types (Kimmel et al.: Journal of Comparative Neurology 205:112–127, 1982; Metcalfe et al.: Journal of Comparative Neurology 251:147–159, 1986). Nineteen of these occur as bilateral pairs which are individually identifiable. Since considerable remolding of brain structures (e.g., cell death and modifications of neuronal architecture) occurs during development, we ask if these cells are preserved in the adult zebrafish and the extent to which neuronal morphology of the larva is conserved during ontogeny. In our analysis, we studied reticular neurons from 84 brains retrogradely labelled from the spinal cord with HRP. We show that all reticulospinal types of the larva are retained without considerable change in morphology in the adult. Many neurons, including the Mauthner cell and two of its serial homologues, MiD2cm and MiD3cm, can be individually and unambiguously identified. In addition, the appearance of later developing (tertiary) neurons leads to an increase in the numbers of some neuron types. Although tertiary neurons are often isomorphic with neighboring cells, they can have unique morphologies of their own and, therefore, are also individually identifiable. We suggest that the appearance of tertiary neurons may serve to extend the behavioural repertoire of the embryo. Moreover, morphological repetitions in adjacent segments of the otic region (level of VIIIth nerve entry) may represent the replication of a functional motif, perhaps involving the C‐type escape response which is known to involve the Mauthner cell.
Distribution of cells containing mRNA encoding cholecystokinin in the rat central nervous system
Authors: Schiffmann S. N. , Vanderhaeghen J.‐J. 
Published: January 2005

AbstractThe distribution of cells containing mRNA encoding cholecystokinin was studied in the rat central nervous system by in situ hybridization histochemistry.Cholecystokinin mRNA containing neurons were considerably more numerous than the cholecystokinin‐like immunoreactive neurons detected by immunocytochemistry even after cholchicine pretreatment and appeared to be heavily, moderately, or lightly labeled. Such neurons were present in the olfactory bulb, olfactory nuclei, layers II–III and V–VI of the cerebral cortex, amygdaloïdnuclei, subiculum, hippocampus, claustrum, endopiriform nucleus, several hypothalamic nuclei, most of the thalamic nuclei, ventral tegmental area, substantia nigra, interfascicularis nucleus, linearis rostralis, central gray, Edinger‐Westphal nucleus, superior and inferior colliculi, parabrachial nucleus, reticular formation, raphe nuclei, and spinal trigeminal nucleus.This distribution partly confirmed and partly extended the previous immunohistochemical descriptions. Several brain areas such as the thalamus and the colliculi contain cholecystokinin mRNA but are devoid of perikarya exhibiting cholecystokinin‐like immunoreactivity. The cerebral cortex and the hippocampus present a far higher density of cholecystokinin mRNA containing cells, including pyramidal neurons, than of perikarya containing cholecystokinin‐like immunoreactivity.These results suggest that cholecystokinin or cholecystokinin‐related peptides could have a functional role in numerous cerebral pathways including long projections such as cortical or thalamic projections.
Incorporation of 3H‐thymidine in telencephalic structures of the vomeronasal and olfactory systems of embryonic garter snakes
Authors: Holtzman David A. , Halpern Mimi 
Published: January 2005

AbstractPrevious studies have shown that the vomeronasal and, possibly, olfactory systems are functional in newborn garter snakes. However, little is known about neurogenesis in these chemosensory pathways. In the companion paper, we describe the embryonic growth of the sensory epithelia for both the vomeronasal and olfactory systems. In the present study, we examine neurogenesis in the telencephalic structures of these chemosensory systems by using 3H‐thymidine autoradiography (ARG). The majority of neurogenesis appears to occur before birth in the accessory and main olfactory bulbs and their principal projection sites, the nucleus sphericus and lateral cortex, respectively. The data suggest that some postnatal neurogenesis may occur in the accessory and main olfactory bulbs and in the nucleus sphericus. Although the neuronal constituents of the accessory and main olfactory bulbs appear to mature concurrently, those of the lateral cortex appear to mature before those of the nucleus sphericus. Along with previous findings, this latter result supports the hypothesis that the olfactory system develops before the vomeronasal system in garter snakes. There appears to be a rostral to caudal gradient of neurogenesis within the mural layer of the nucleus sphericus. However, an “outside to inside” gradient of neurogenesis was not observed in the mantle layer of the lateral cortex, as described for other reptiles. Similarities and differences observed by other investigators in other reptilian species and mammals are discussed.
Ontogeny of somatostatin receptors in the rat somatosensory cortex
Authors: Gonzalez Bruno J. , Leroux Philippe , Bodenant Corinne , Vaudry Hubert 
Published: January 2005

AbstractThe distribution and density of SRIF receptors (SRIF‐R) were studied during development in the rat somatosensory cortex by in vitro autoradiography with monoiodinated [Tyr0‐DTrp8]S14. In 16‐day‐old fetuses (E16), intense labeling was evident in the intermediate zone of the cortex while low concentrations of SRIF‐R were detected in the marginal and ventricular zones. The highest density of SRIF‐R was measured in the intermediate zone at E18. At this stage, labeling was also intense in the internal part of the developing cortical plate; in contrast, the concentration of binding sites associated with the marginal and ventricular zones remained relatively low. Profound modifications in the distribution of SRIF‐R appeared at birth. In particular, a transient reduction of receptor density occurred in the cortical plate. During the first postnatal week, the density of receptors measured in the intermediate zone decreased gradually; conversely, high levels of SRIF‐R were observed in the developing cortical layers (II to VI). At postpartum day 13 (P13), a stage which just precedes completion of cell migration in the parietal cortex, the most intensely labeled regions were layers V–VI and future layers II–III. From P13 to adulthood, the concentrations of SRIF‐R decreased in all cortical layers (I to VI) and the pattern of distribution of receptors at P21 was similar to that observed in the adults.Detailed analysis of the results revealed (i) a close association between the distribution of SRIF‐R and the areas containing migrating neuroblasts and (ii) a temporal correlation between the presence of SRIF‐R and the transient expression of the neuropeptide SRIF in the developing somatosensory cortex. Taken together, our data suggest the existence of two populations of SRIF‐R: a transient population, which could be implicated in the development of the parietal neocortex from E16 to P13, and a population of SRIF‐R only expressed after the first postnatal week, which is likely to be involved in the process of neurotransmission.
Complementary global maps for orientation coding in upper and lower layers of the cat striate cortex and their possible functions
Authors: Bauer R. , Leferink J. , Eckhorn R. , Jordan W. 
Published: January 2005

AbstractPreferred stimulus orientations of striate cortical cells in the cat were analyzed for possible isotropic or anisotropic distributions. We separated the data twice, into central (0–5°) vs. peripheral subgroups and into upper vs. lower layer cells. In the central group, absolute orientations were counted; in the periphery, a radial test was adopted by normalizing the preferred stimulus orientation of a cell to the line connecting the receptive field center to the retinal center. We found that in the center, vertical and horizontal orientations are overrepresented. In the periphery, the histograms show complementary anisotropies for upper and lower layers, favoring a map for radial orientation detection in upper layers and a more concentric map for orientation detection in lower layers.These results are possibly related to the probabilities different optic flow fields on the retina under natural conditions of stimulation. They are discussed as possible neuronal structures supporting figure‐ground discrimination, the distinction of self motion from object motion, and the location of objects in three‐dimensional space.