bluuebunny/crossref_metadata_2025_split huggingface dataset:
The organization of the motoneurons innervating the axial musculature of vertebrates. I. Goldfish (Carassius auratus) and mudpuppies (Necturus maculosus)
Authors: Fetcho Joseph R. 
Published: January 2005

AbstractThe motoneurons innervating different regions of the myomeres in goldfish and mudpuppies were examined by applying HRP to the musculature or to branches of spinal nerves. In goldfish, the populations of motoneurons innervating epaxial or hypaxial muscle occupied similar positions in the motor column and had similar size distributions. There was no relationship between the size or location of a motoneuron in the motor column and the dorsoventral location of the muscle it innervated in the myomeres. Instead, different populations of motoneurons innervated the functionally different red and white musculature. The red muscle was innervated only by small motoneurons that occupied the ventral portion of the motor column. Their small axons passed lateral to the Mauthner axon in the cord, and most of them traveled in a separate branch of each spinal nerve that ran in the horizontal septum to the red muscle. The white muscle was innervated by a population of motoneurons that did not innervate red. They were large and they occupied a characteristic position in the extreme dorsal part of the motor column. Their large axons traveled medial to the Mauthner axon in the cord and entered branches of spinal nerves running deep in the epaxial or hypaxial muscle. The white muscle was probably also innervated by some smaller motoneurons similar to those innervating red; however, these may have been motoneurons whose axons ran through white muscle to reach other muscle. The large motoneurons innervating only white muscle are similar to the primary motoneurons identified in developmental studies in teleosts (Myers: Soc. Neurosci. Abstr. 9:848, '83); the smaller ones, innervating both red and white, are like secondary motoneurons. Therefore, in goldfish, motoneurons having different morphology and developmental history also innervate different regions in the myomeres.The motor column in mudpuppies was, in general respects, similar to the column in goldfish. There were large primary motoneurons and small secondary ones. Though there were slight differences in the locations of motoneurons filled from nerves entering epaxial and hypaxial muscle, their distributions in the cord overlapped substantially.The motor columns in these two anamniotes differ substantially from the motor columns in those amniotes that have been studied. In amniotes, the motoneurons innervating epaxial and hypaxial muscles are spatially segregated in the cord (Smith and Hollyday: J. Comp. Neurol 220:16‐28, '83; Fetcho: J. Comp. Neurol 249:551‐563, '86). The absence of a comparable segregation in goldfish and mudpuppies implies that the medial motor column has undergone a major reorganization during the evolution of vertebrates.
Ultrastructural organization of choline acetyltransferase‐immunoreactive fibres innervating the neocortex from embryonic ventral forebrain grafts
Authors: Clarke Deborah J. , Dunnett Stephen B. 
Published: January 2005

AbstractSuspension grafts of foetal tissue rich in cholinergic neurones were transplanted into the frontoparietal cortex of rats that had previously undergone deafferentation of the extrinsic cholinergic innervation of the cortex by injection of ibotenic acid into the nucleus basalis magnocellularis. The cortical tissue containing the graft was processed for electron microscopic immunocytochemistry by using a monoclonal antibody to choline acetyltransferase (ChAT) in order to examine the contacts established between cholinergic fibres from the graft and the host neocortex. The density, distribution, and targets of this graft‐host innervation were compared with those seen in the intact and deafferented cortex. ChAT‐positive fibres in both grafted and control animals formed extensive synaptic connections with various cortical neural elements–those of graft origin being of similar morphology to those in the intact cortex. However, the distribution of postsynaptic cortical targets of the graft‐derived ChAT‐immunoreactive boutons was abnormal, such that a greater percentage of such terminals formed synaptic contacts with neuronal perikarya, especially layer V pyramidal neurones, than was seen in control brains. It is possible that the formation of new synaptic contacts between the embryonic graft and host frontoparietal cortex may, in part, be necessary for the restoration of functional activity that has been previously reported in these grafted animals.
The organization of hypothalamocerebellar cortical fibers in the squirrel monkey (Saimiri sciureus)
Authors: Haines D. E. , Dietrichs E. , Culberson J. L. , Sowa T. E. 
Published: January 2005

AbstractThe organization and distribution of hypothalamocerebellar cortical fibers in squirrel monkey were investigated by using horseradish peroxidase (HRP, WGA‐HRP) and 3H‐leucine as anterograde tracers. Following hypothalamic injections, anterogradely labeled fibers coursed bilaterally through the periventricular gray (ipsilateral preponderance) and into the cerebellar white matter. Sparse numbers of labeled fibers appeared to descend into the reticular formation and enter the cerebellum via the brachium pontis.The pattern of cerebellar cortical labeling does not conform to that of mossy or climbing fibers. Labeled axons enter and branch within the granular layer, proceed around Purkinje cell somata, and enter the molecular layer. Within the latter some labeled fibers branch outwardly in a fanlike manner whereas others ascend before branching. Many fibers within the molecular layer ultimately assume an orientation that is similar to that of parallel fibers. The distribution patterns of hypothalamocerebellar cortical axons resemble those reported for monoaminergic fibers in the cerebellar cortex. Afferent fibers to the cerebellar cortex (including hypothalamocerebellar) that do not terminate as mossy or climbing fibers may collectively constitute a third general category of cerebellar afferent axons. On the basis of their distribution within all cortical layers these fibers are designated as multilayered fibers.The morphology of multilayered fibers stands in contrast to the presumptive mossy fiber labeling seen in lobules IX and X following large injections. Such labeling may represent a subpopulation of hypothalamocerebellar fibers or result from enzyme deposition in areas bordering the hypothalamus that project to cerebellar structures.
Effects of unilateral and bilateral cochlea removal on 2‐deoxyglucose patterns in the chick auditory system
Authors: Heil Peter , Scheich Henning 
Published: January 2005

AbstractThe 2‐deoxyglucose (2DG) method was used to map functional activity in the auditory system of chicks that had been subjected to unilateral or bilateral cochlea removal. Following survival times of 1 day to 4 weeks, chicks were exposed to continuous white noise in the 2DG experiments. In monaural subjects nucleus angularis and nucleus magnocellularis showed faint 2DG uptake on the side contralateral to the intact ear. In the binaural nucleus laminaris, the asymmetrical and almost mirror‐imaged labeling pattern (Lippe, Stewart, and Rubel: Brain Res. 196:43–58, '80) was produced. The superior olive (OS) was strongly labeled on the ipsilateral side, whereas the contralateral OS showed only a slight 2DG uptake at its medial border. The lateral lemniscus and nucleus lemnisci lateralis, pars ventralis (LLv) showed stronger activation on the contralateral side. Both Nissl stains and 2DG patterns provide evidence that nucleus ventralis lemnisci lateralis (VLV) can be subdivided into an anterior (VLVa) and a posterior (VLVp) part. Whereas VLVp is labeled only contralaterally, VLVa is labeled on both sides with similar intensity. Nucleus mesencephalicus lateralis, pars dorsalis (MLD) is strongly labeled throughout contralaterally. The ipsilateral MLD shows a defined ventral portion of high 2DG uptake. Intensity of labeling here is symmetrical to the corresponding area of the contralateral MLD. These symmetrical patterns were related to the tonotopic organization of MLD, which was mapped in intact animals by using tone stimuli. Assuming that symmetrical 2DG uptake in monaural animals indicates excitatory input from both ears (EE‐cells), it appears that these EE‐cells occupy a sector of each isofrequency plane in MLD. Nucleus ovoidalis (Ov) generally was stronger labeled on the contralateral side. The columnar organization of field L as seen in monaural chicks has already been described (Scheich, Exp. Brain Res. 51:199–205, '83). In bilaterally deafened chicks, MLD, Ov, and layer L2 of field L showed strong but spatially restricted 2DG accumulation in contrast to absence of labeling in peripheral nuclei.The 2DG patterns in monaural chicks are likely to reflect excitatory input within the auditory system. In addition they reveal new insights into the functional organization of some of its nuclei. In particular, they support the notion that MLD contains maps of several interaural integration mechanisms similar to field L. Labeling in the auditory system of bilaterally deafened chicks may result from descending projections or from other than auditory inputs.
Mystacial vibrissae representation within the trigeminal sensory nuclei of the cat
Authors: Nomura Sakashi , Itoh Kazuo , Sugimoto Tetsuo , Yasui Yukihiko , Kamiya Hiroto , Mizuno Noboru 
Published: January 2005

AbstractSomatotopic arrangements of axon terminals of primary afferent fibers innervating follicles of the mystacial vibrissae were examined in the cat by the transganglionic horseradish peroxidase (HRP) method. Forty to 60 hours after injecting HRP into a single or a group of vibrissal follicles, transported HRP was visualized by the tetramethylbenzidine technique. HRP‐labeled axon terminals were distributed in the ventral subnucleus of the principal sensory trigeminal nucleus (ventral Vp), in the oral and interpolar spinal trigeminal nuclei (Vo and Vi), and in the caudal spinal trigeminal nucleus (Vc) (layer I, deep part of layer II, layers III–V) with its spinal extension into the dorsal horn of the first cervical cord segment (rostral C1). In cross sections through the caudal parts of the ventral Vp, Vi, and layer IV of the Vc and rostral C1, a single mystacial vibrissa was represented in a one‐to‐one fashion by a patch of dense terminal arbors of primary afferent fibers. The more dorsally a horizontal row of the mystacial vibrissae was located, the more ventrally was it represented in the ventral Vp, the more ventrolaterally in the Vi, and the more ventrally in layer IV of the Vc and the rostral C1. In addition, the more anteriorly a vibrissa was located in a horizontal row of the mystacial vibrissae, the more medially was it represented in the ventral Vp, the more ventromedially in the Vi, and the more laterally in layer IV of the Vc and rostral C1; the most posteriorly located vibrissae in the horizontal rows of the mystacial vibrissae were represented along the lateral border of the ventral Vp and Vi, and most medially in layer IV of the Vc and rostral C1. Thus, the representation pattern in the ventral Vp was rotated clockwise at about 45° angle in the Vi, and projected as a mirror image in layer IV of the Vc and rostral C1. It was also indicated that the anterior‐posterior arrangement of the mystacial vibrissae was represented in a rostral‐caudal organization within layer IV of the Vc and rostral C1. It was also indicated that the anterior‐posterior arrangement of the mystacial vibrissae was represented in a rostral‐caudal organization within layer IV of the Vc and rostral C1.Patchy patterns probably replicating the distribution of the vibrissae on the face of the cat were also revealed by the cytochrome oxidase histochemical staining in cross sections through the caudal parts of the ventral Vp, Vi, and layer IV of the Vc and rostral C1.
The influence of testosterone on the sex‐dependent structural asymmetry of the medial habenular nucleus in the chicken
Authors: Gurusinghe Chandan J. , Zappia Joseph V. , Ehrlich David 
Published: January 2005

AbstractThe volume of the left and right medial habenular nuclei of male and female chicks was analysed for evidence of structural asymmetry. The influence of exogenous testosterone on habenular asymmetry was also examined. Male and female chickens were injected intramuscularly with either testosterone enanthate or an oil vehicle on day 2 (15 animals per group) and were perfused at days 5, 12, and 19 respectively. Paraffin sections (8 μm) containing the medial habenular nucleus were stained with cresyl violet and both left and right medial habenular nuclei were measured by planimetry. In control chicks, males had structural asymmetry at day 12, whereas females did not show any structural asymmetry. Testosterone did not appear to influence asymmetry in the male chick but induced structural asymmetry at all three ages in the female to favour the right hemisphere. This study demonstrates a role for testosterone in influencing structural asymmetry of a nucleus in the vertebrate brain.
Corticospinal neurons with branching axons to the dorsal column nuclei in the monkey
Authors: Bentivoglio M. , Rustioni A. 
Published: January 2005

AbstractPrevious work in cats has shown that cells of origin of the corticospinal tract give rise to collateral branches to the dorsal column nuclei (DCN). The present experiments were performed in monkeys (Macaca fascicularis) in which 2% fast blue and 2% diamidino yellow were delivered to infiltrate the dorsolateral funiculus at levels between C2 and C6 and the cuneate nucleus on the same side. Retrograde labelling in the cortex allows simultaneous visualizaion of three classes of neurons: corticospinal tract (CST) neurons, corticocuneate tract (CCT) neurons, and double‐labelled neurons. The morphological features and distribution of CST and CCT neurons are similar to those previously reported from investigations based mainly upon the retrograde transport of horseradish peroxidase (HRP). CST neurons occur in layer V in the pre‐ and postcentral gyri, except for the lateral part (face representation), in the supplementary motor and sensory cortex, and in SII. CCT neurons are present in layer V largely in the postcentral gyrus and in SII. Double‐labelled neurons are present wherever CST and CCT neurons are found. Reconstruction and quantitative data from the pericentral corted show that up to 60% of CCT neurons are double‐labelled and are found predominantly in areas 1 and 2, and that their perikarya are in the size range of the larger CCT neurons.Comparison of these results with those obtained previously in cats by using HRP and tritiated, enzymatically inactive HRP (3H‐apo‐HRP, Rustioniand Hayes: Exp. Brain Res. 43:237–245, 1981) suggests that CST neurons with branching axons to the DCN are considerably more numerous in monkeys than in cats. To determine whether this difference is caused by the different tracers used in the two species. 2% fast blue and 2% diamidino yellow were delivered in cats to infiltrate the dorsolateral funiculus at C2‐C3 and the nucleus on the same side. The results in these cats are remarkably similar to those obtained in the previous study, which used HRP and 3H‐apo‐HRP: double‐labelled neurons occur predominantly in area 3a and constitute 14–16% of the CCT neurons in the pericruciate area.The results bear upon mechanisms of descending control and tuning of performances that characterize the dorsal column‐medial lemniscal system, e.g., discrimination of discrete spatiotemporal cues. The species differences may be related to the higher degree of tactile resolution and synchronous control of sensory inflow at the DCN and spinal cord in monkeys relative to cats.
Quantification of thalamocortical synapses with spiny stellate neurons in layer IV of mouse somatosensory cortex
Authors: Benshalom Gadi , White Edward L. 
Published: January 2005

AbstractThe distribution of thalamocortical (TC) and other synapses involving spiny stellate neurons in layer IV of the barrel region of mouse primary somatosensory cortex (SmI) was examined in seven male CD/1 mice. TC axon terminals were labeled by lesion‐induced degeneration, which has been shown to label reliably all TC synapses in mouse barrel cortex. Spiny stellate neurons, labeled by Golgi impregnation and gold toning, were identified with the light microscope prior to thin sectioning and electron microscopy. Analysis of eight dendritic segments from seven spiny stellate neurons showed that most of their synapses are with their dendritic spines, rather than with their shafts. Axospinous synapses are primarily of the asymmetrical type, whereas axodendritic synapses are mainly of the symmetrical type. Dendrites of spiny stellate neurons consistently form thalamocortical synapses, most of which involve spine heads rather than spine stalks or dendritic shafts. From 10.4% to 22.9% of all asymmetrical synapses with dendrites of spiny stellate neurons involve TC axon terminals. In general, this is a higher range than the ranges that characterize the TC synaptic connectivity of dendrites belonging to other types of neurons, implying that spiny stellate neurons are perhaps more strongly influenced by TC synaptic Input than other types of cortical neurons examined previously. Spines involved in TC synapses were distributed irregularly along each of the stellate cell dendrites; about half of the interspinous intervals between these spines were about 5 μm or less. Modulations of the efficacy of TC synaptic input to dendrites of layer IV spiny stellate neurons are discussed in the light of recently reported computer simulated analyses of axospinous synaptic connections.
Neurotensin binding sites in the forebrain and midbrain of the pigeon
Authors: Brauth Steven E. , Kitt Cheryl A. , Reiner Anton , Quirion Remi 
Published: January 2005

AbstractAn autoradiographic method was used to assess the distribution of binding sites for [3H] neurotensin (NT) in the forebrain and midbrain of the pigeon. Within the telencephalon the highest levels of NT binding sites were observed within the hyperstriatum ventrale (HV). Moderate to high levels of NT binding were observed within the archistriatum, neostriatum intermedium, and hyperstriatum accessorium. These telecephalic regions and HV are thought to be comparable to portions of mammalian neocortex. Lower levels of binding sites were observed within the striatal complex including the laterally situated paleostriatum augmentatum and medially situated lobus parolfactorius. The lowest levels of NT binding sites in the telencephalon were observed within the paleostriatum primitivum (PP, considered comparable to mammalian globus pallidus), ectostriatum (comparable to layer IV of mammalian extrastriate visual cortex), field “L” (comparable to layer IV of mammalian auditory cortex), hippocampus, septum, and preoptic area. Despite considerable regional variation, the overall level of NT binding throughout the pigeon telencephalon appears to be significantly higher than that reported for mammals, particularly within pallial areas.Within the brainstem, moderate levels of NT binding sites were observed in the lateral habenular nuclei, the ventral tegmental area of Tsai, nucleus tegmentipedunculopontinus, pars compacta (comparable to the mammalian substantia nigra, pars compacta), locus coeruleus, and the nucleus subcoeruleus dorsalis. The latter four cell groups contain numerous catecholaminergic neurons. Corresponding catecholaminergic cell groups in mammalian forms also contain high levels of NT receptors. As in mammals, lower levels of NT binding were observed in most diencephalic nuclei. Somewhat higher levels of NT binding were observed within the pretectal nuclei spiriformis lateralis and spiriformis medialis. Moderate levels of NT binding sites were observed within the retinal terminal layers of the tectum (i.e., layers 1–7).Immunohistochemical experiments (Reiner and Carraway; Brain Res. 341:365–371, '85; Reiner: ARVO Abstracts: p. 185,'86) lccalizing NT and a related hexapeptide, LANT6, have shown that LANT6 is present in retinal ganglion cells, in cells of the paleostraitum, and in the striatoitegmental and striatopretectal fiber pathways of the pigeon. Thus some features of the NT binding observed here in pigeon brain including the existence of substantial NT binding sites in the brainstem catecholamine nuclei, pretectum (nucleus spiriformis lateralis), and optic tectum may reflect the existence, at least in part, of functional receptors for LANT6. The possibility that the tritiated NT ligand used in this study may bind to the same receptors as LANT6 is discussed in detail.
Motoneurons of the tail of young xenopus tadpoles
Authors: Nordlander Ruth H. 
Published: January 2005

AbstractThe purpose of this study was to identify, characterize, and follow the morphogenesis of motoneurons innervating tail myotomes of Xenopus during early and middle larval stages (33–48). Application of horseradish peroxidase to a single myotome results in a column of labeled motor cells extending over four spinal segments. By midlarval stages two morphologically distinct cell types were recognizable in this column‐primary and secondary motoneurons. Primary motoneurons occupied the more rostral and secondary motoneurons the more caudal portions of the column with some overlap of the two populations. Primary neurons developed earlier, were larger, and displayed thicker axons and proximal dendrites. Secondary neurons, in contrast, were smaller, more variable in configuration and dendritic distribution, and displayed thinner axons and dendrites. Development of the labeled motor column during the period observed involved the addition of more labeled neurons, principally secondary cells, and the enlargement of individual cell somata with the progressive elaboration of more and longer dendrites into the developing lateral fasciculus.
Morphology of neurons in the dorsal lateral geniculate complex in turtles of the genera Pseudemys and Chrysemys
Authors: Todd Rainey W. , Ulinski Philip S. 
Published: January 2005

AbstractThe morphology of neurons in the dorsal lateral geniculate complex of pond turtles has been studied by extracellular filling with horseradish peroxidase.The dorsal lateral geniculate complex is a rostrocaudally elongate structure that includes the nucleus ovalis and dorsal lateral geniculate nucleus of Papez. It is divided into three cytoarchitecturally distinct subnuclei: (1) the subnucleus ovalis, (2) the dorsal subnucleus, and (3) the ventral subnucleus. Each subnucleus consists of a neuropile immediately internal to the optic tract and a cell plate of densely packed somata forming the medial face of the complex. The cell plate contains medial (or parvicellular) and lateral (or magnocellular) sublaminae that are separated by a cell‐poor zone in subnucleus ovalis and the ventral subnucleus. The density and size of somata vary between subnuclei.Geniculate neurons fall into two distinct groups. Cell plate neurons have somata in the cell plate and vary substantially in morphology. Those in the medial sublamina have fusiform somata and dendrites that extend either mediolaterally (subnucleus ovalis) or run rostrocaudally in the cell plate (dorsal and ventral subnuclei). Those in the lateral sublamina have some dendrites that extend medially within the cell plate and others that extend into the neuropile. The latter dendrites branch and bear arbors of fingerlike, varicose branchlets in the outer half of the neuropile. By contrast, neuropile cells have fusiform somata and dendrites extending concentrically with the optic tract in the neuropile. Both groups of geniculate neurons can be retrogradely labeled by horseradish peroxidase injections in the lateral forebrain bundle.These results lead to the recognition of two principles of geniculate organization in turtles. The first is that the geniculate complex is divided into three subnuclei that vary in size and density of their neurons. The second is that the complex has a form of laminar organization different than that seen in the geniculate complex of mammals.