bluuebunny/crossref_metadata_2025_split huggingface dataset:
The sprouting of saphenous nerve terminals in the spinal cord following early postnatal sciatic nerve section in the rat
Authors: Fitzgerald Maria 
Published: January 2005

AbstractTransganglionic labelling of the saphenous nerve in rats with WGA‐HRP revealed the central distribution of its terminals in the lumbar dorsal horn. The terminal field was clearly defined and consistent in rats aged between day 6 and day 90. If, however, the sciatic nerve was sectioned on day 1 of postnatal life, the saphenous terminal field expanded to occupy twice the normal area (measured between the L2 and L4 boundaries). The spread was caudal, medial, and lateral into areas normally occupied by sciatic nerve terminals. This sprouting was very weak if the sciatic nerve was sectioned later in postnatal life, on day 5, and nonexistent if sectioning took place on day 10. Crushing the sciatic nerve on day 1 also triggered the effect but the spread of the terminal field was less than that produced by section of the sciatic nerve. There was no evidence of sprouting from the contralateral intact sciatic nerve. The results demonstrate the necessity of intact afferent input during a critical period of neonatal life in order to maintain the precise somatotopic termination pattern of dorsal root afferents.
The spinal distribution of sympathetic preganglionic and visceral primary afferent neurons that send axons into the hypogastric nerves of the cat
Authors: Morgan C. , de Groat W. C. , Nadelhaft I. 
Published: January 2005

AbstractThe spinal distribution of sympathetic preganglionic neurons (PGN) and visceral primary afferent neurons sending axons into the hypogastric nerve of the cat has been studied with HRP tracing techniques. After application of HRP to the cat hypogastric nerve, labeled PGN were identified in segments L2‐L5. Most of these neurons were oriented transversely and were divided approximately equally between two nuclei: the principal, nucleus and the intercalated nucleus. Cells were distributed in clusters at 160‐361‐μm intervals along the length of the cord. Sensory neurons were labeled in dorsal root ganglia from T12 to L5. Central axons of these visceral afferents were observed in the medial half of Lissauer's tract from T13 to L7. Afferent axon collaterals extended through lamina I on both sides of the dorsal horn but were most prominent on the lateral side, where they continued into lateral lamina V and VII, often overlapping the dorsal dendrites of PGN in this region. Labeled afferent projections exhibited a periodic distribution in lamina I with clusters of axons occurring at 235‐343‐μm intervals in the rostrocaudal axis. The central projection of hypogastric nerve primary afferents was qualitatively similar to the distribution of visceral afferent projections at other levels of the spinal cord.
Organization of motor pools supplying the cervical musculature in a cryptodyran turtle, Pseudemys scripta elegans. I. Dorsal and ventral motor nuclei of the cervical spinal cord and muscles supplied by a single motor nucleus
Authors: Yeow M. B. L. , Peterson E. H. 
Published: January 2005

AbstractIn this and the accompanying paper (Yeow and Peterson, '86) we characterize motor nuclei of the cervical spinal cord in Pseudemys scripta and the motor pools of eight cervical muscles. We have identified three motor nuclei that supply the cervical musculature by using serial reconstructions of Nissl‐stained spinal cords cut in three cardinal planes, and in experimental cases in which horseradish peroxidase (HRP) was applied to individual neck muscles. These nuclei are named according to their position as visualized in the transverse plane: (1) dorsal, (2) ventral, and (3) medial. A fourth (ventrolateral) motor nucleus was never labelled following application of HRP to the cervical musculature and presumably innervates the forelimbs. The dorsal motor nucleus occupies the mid‐dorsal to dorsolateral ventral horn of C1 and C2. It is composed of at least two morphological groups of motor neurons; one of these is a population of very large, fusiform profiles with transversely oriented dendrites that is found primarily in C1. The ventral motor nucleus occupies the tip of the ventral horn from C1 to C8. Its cells are significantly smaller and more numerous in rostral than in caudal cervical segments. In Nissl material, ventral nuclear, profiles show little tendency to cluster into subgroups, but experimental cases suggest that there is some spatial dissociation of different motor pools within the ventral nucleus. The medial motor nucleus is described in the accompanying paper together with the motor pools of three cervical muscles that it supplies.Having identified the cervical motor nuclei we then used retrograde transport of HRP to characterize the motor pools of individual cervical muscles. Two superficial ventral muscles (mm. coracohyoideus and plastrosquamosus) are supplied by dorsal nuclear cells. M. coracohyoideus motor neurons are significantly larger than those of m. plastrosquamosus and the very large, fusiform cell type is relatively more numerous in the m. coracohyoideus motor pool. Dorsal and lateral muscles (mm. cervicocapitis, testocapitis, and transversalis cervicis) are supplied by ventral nuclear motor neurons. These cells are smaller, on average, than motor neurons supplying ventral musculature. The m. cervicocapitis motor pool lies dorsomedially in the tip of the ventral horn of C1 and C2; motor neurons supplying the more laterally placed mm. testocapitis and transversalis cervicis occur more ventrolaterally, in C2–C3 and C3–C5, respectively. Thus each of the five cervical muscles is supplied by a single motor nucleus, and their motor pools are organized into a musculotopic pattern.
Ocular dominance columns and retinal projections in new world spider monkeys (Ateles ater)
Authors: Florence S. L. , Conley M. , Casagrande V. A. 
Published: January 2005

AbstractRetinal projections and the degree of ocular segregation in the striate cortex were examined by transneuronal autoradiography following unilateral intraocular injections of 3H‐proline in a New World primate, the spider monkey (Ateles ater). The results show that, within the lateral geniculate nucleus (LGN), retinal fibers terminate in six principal layers and within the interlaminar spaces adjacent to the magnocellular layers, as well as the S layers ventral to the magnocellular layers. Projections to the superior colliculus, both ipsilateral and contralateral to the injected eye, were patchy and restricted to the superficial gray layer.Our main result shows that, in the striate cortex, LGN projections terminate in well‐defined ocular dominance columns in layer IV. Labelled columns were most clearly delimited in layer IVb, where they averaged 373 + 42μm in width in both the ipsilateral and contralateral hemipheres, slightly smaller than those reported originally from electrophysiological studies of striate cortex in spider monkeys (Hubel and Wiesel, '68). Unlabelled intercolumns were significantly narrower than labelled columns, which suggests that there may be overlap between input from the two eyes between columns. Quantitative measures showed above‐background label also in cortical layers IIIb, V, and VI.Our results support the idea that among primates, ocular dominance columns are not limited to Old World species. At the same time, it is apparent that spider monkeys are exceptional among New World primates in having sharply delimited columns. The functional significance of the variation in the degree of ocular segregation in the cortex and its relation to primate evolution are discussed.
The organization of divergent axonal projections from the midbrain raphe nuclei in the rat
Authors: Imai H. , Steindler D. A. , Kitai S. T. 
Published: January 2005

AbstractThe intranuclear organization of divergently projecting neurons of the midbrain raphe in the rat was studied by using double retrograde axonal tracing. Paired injections of the tracers N‐[acetyl‐3H] WGA and horseradish peroxidase were made within known projection targets of the midbrain raphe (caudate‐putamen, amygdala, hippocampus, substantia nigra, and locus coeruleus).After injections of either tracer in the aforementioned targets, retrograde labeled neurons were found mainly ipsilaterally and within midline portions of the dorsal raphe nucleus, its caudal B6 portion, and within the linear and superior central nuclei of the median raphe complex. There are discrete intranuclear distributions of raphe neurons that project to these forebrain and brainstem sites, and there is an overall rostrocaudal topographic order within the raphe with neurons projecting to the neostriatum, amygdala, and substantia nigra residing most rostrally and neurons projecting to the hippocampus and/or locus coeruleus occupying caudal portions of the B6 and superior central nuclei. Such distributions of projection neurons suggest the existence of an “encephalotopic” intranuclear organization within the raphe; that is, each central nervous system structure that receives midbrain raphe projections has its own unique representation within a topographically distinct portion of one or more of the raphe subgroups.These findings suggest an overall functional organization within the midbrain raphe nuclear complex whereby rostral portions are associated with the basal ganglia and related nuclei, and caudal portions relate to the limbic system. An intermediate representation of amygdala‐projecting raphe neurons functionally conjoins the two. Collateralized neurons are found within complex zones of overlap in the topographically organized distributions of raphe neurons projecting to functionally related structures.
The origin, course, and termination of the hippocampothalamic projections in the macaque
Authors: Aggleton J. P. , Desimone R. , Mishkin M. 
Published: January 2005

AbstractThe projections from the hippocampal formation to the thalamus were investigated with both anterograde and retrograde tracers. Horseradish peroxidase was injected into medial and midline thalamic sites in six cases, and tritiated amino acids were injected into the hippocampal formation in nine others, five of which had prior transections of the fornix. Only the subicular and entorhinal cortices were found to project to the thalamus. From the subicular cortex, dense bilateral projections were traced through the fornix to the anterior nuclei, while lighter fornical projections terminated in other rostral midline sites, including the nuclei reuniens, centralis latocellularis, and paraventricularis. These projections arose predominantly from the polymorphic cells which are located in the deepest cellular layers of the subiculum and prosubiculum. In addition, the subicular cortex was found to project to the nucleus lateralis dorsalis. The latter projection, which showed evidence of a crude topographic organization, ran either through the fornix or, unlike the other subicular efferents, through the sublenticular limb of the internal capsule to form part of the temporopulvinar bundle of Arnold. The nonfornical projection to the nucleus lateralis dorsalis passed through the medial pulvinar, where there was some additional termination. Few, if any, projections from the entorhinal cortex to the thalamus travelled in the fornix. Rather, the entorhinal efferents were carried in the inferior thalamic peduncle to the magnocellular portion of the nucleus medialis dorsalis, and in the internal capsule and bundle of Arnold to the medial pulvinar and the nucleus lateralis dorsalis.
Nucleus Z in the rat: Spinal afferents from collaterals of dorsal spinocerebellar tract neurons
Authors: Low Joni S. T. , John Louise A. Mantle‐St. , Tracey David J. 
Published: January 2005

AbstractProprioceptive information from the hindlimb of the cat is now known to be relayed to the somatosensory thalamus and cortex via axons in the dorsolateral fasciculus and a medullary relay in nucleus z. The aim of this study was to identify nucleus z in the rat, to locate the cells of origin of spinal afferents to nucleus z, and to determine whether they are collaterals of the dorsal spinocerebellar tract.The location and extent of nucleus z were studied by filling the axon terminals of collaterals of the dorsal spinocerebellar tract (dsc) with horseradish peroxidase (HRP), which was injected into the inferior cerebellar peduncle. Nucleus z in the rat was found to be similar in location to nucleus z in other mammals. It was located just below the dorsal surface of the medulla, bounded laterally by the rostral pole of the cuneate nucleus and medially by the nucleus of the solitary tract.The cells of origin of the spinal afferents to nucleus z were studied by using the retrograde transport of HRP. They were located in Clarke's column (dorsal nucleus) and in lamina 10 of the dorsal horn. They were similar in location and morphology to neurons giving rise to the dorsal spinocerebellar tract, but were smaller in average diameter.A double retrograde labeling technique was used to determine whether the spinal afferents to nucleus z are collaterals of neurons giving rise to the dsc. It was estimated that up to 92% of the spinal afferents to nucleus z were collaterals of dsc neurons, while approximately 3% of all dsc neurons gave rise to collaterals terminating in nucleus z.
Neural tissue transplants rescue axotomized rubrospinal cells from retrograde death
Authors: Bregman Barbara S. , Reier Paul J. 
Published: January 2005

AbstractRubrospinal tract cells undergo massive retrograde degeneration following spinal cord damage in newborn rats (Prendergast and Stelzner, J. Comp. Neurol. 166:163–172, '76b). In the current study, fetal spinal cord tissue (E12–14) was grafted into midthoracic spinal cord lesions in newborn rats (<72 hours old) in order to determine whether such transplants could modify the response of the immature host central nervous system (CNS) to axotomy. These transplants grew, differentiated, and formed extensive areas of apposition with the recipient spinal cords. Counts of red nucleus (RN) neurons indicated a significant loss of RN neurons in animals with lesion alone, but a rescuing of most of these cells if a transplant was placed into the lesion site. In fact, the number of neurons in animals with lesions and transplants was not significantly different from control animals. Horseradish peroxidase injected 10–15 mm caudal to the transplant (at 1–12 months post‐transplantation) labeled neurons within the transplant and RN neurons contralateral to the spinal cord lesions and transplant. In animals with spinal cord lesion but no transplant, only the unaxotomized RN was labeled. Thus, spinal cord transplants prevented the massive retrograde cell death of immature axotomized rubrospinal neurons. Some of these rescued neurons projected to the host spinal cord caudal to the transplant.
Postnatal loss of axons in normal rat sciatic nerve
Authors: Jenq Chung‐Bii , Chung Kyungsoon , Coggeshall Richard E. 
Published: January 2005

AbstractMyelinated and unmyelinated axons were counted in sciatic nerves of newborn, 5‐day‐old, 14‐day‐old, and adult rats. Myelinated axons increase from essentially none at birth to approximately 8,000 in adulthood, but total axon numbers decrease steadily from 33,954 at birth to 22,872 in adulthood. Thus there is a significant postnatal loss of axons from rat sciatic nerve. This loss is, in our opinion, not associated with the death of the cells that give rise to these axons. This is thus an example of a regressive event that probably is of importance in normal neural development, namely the postnatal elimination of axons unaccompanied by death of the neurons that give rise to axons. These findings presumably imply a considerable amount of proximal peripheral axon branching, and the postnatal elimination of axons in the sciatic nerve presumably results from a reduction of this branching. Thus postnatal elimination of processes on, for example, somatic muscle cells may be at least partially the result of long axon elimination rather than local withdrawal of presynaptic processes, as is usually thought to be the case. In addition, an increased number of axons resulting from early postnatal manipulations may indicate cessation of axon loss rather than formation of new axons.
Spiking local interneurones in the mesothoracic ganglion of the locust: Homologies with metathoracic interneurones
Authors: Burrows M. , Watkins B. L. 
Published: January 2005

AbstractTwo bilaterally symmetrical groups of spiking local interneurones have been characterized in the mesothoracic ganglionn of the locust. The cell bodies of one group, the “midline group,” lie at the ventral midline. Their primary neurites run in the ventral loop of ventral commissure II to form extensive branches in the neuropile of one‐half of the ganglion. A dorso‐ventral process in the perpendicular tract links two distirfct fields of branches, one ventral and consisting of numerous fine branches of a uniform texture that arise from stout secondary neurites, and the other more dorsal consisting of fewer branches of a varicose appearance. Cell bodies of the second, the “anteriorlateral” group, lie close to the lateral edge of an anterior connective. Their primary neurites run in a more anterior ventral commissure and their neuropilar branches are divided into two fields by a process in a more anterior dorso‐ventral tract. Within the two groups, each interneurone has its‐own distinctive shape that is an elaboration on these basic plans. Each interneurone also has its own characteristic physiology, being excited by a particular array of mechanoreceptors on the middle leg on the same side of the body as its neuropilar branches. The receptive fields of the interneurones, defined in this way, can be extensive and cover a particular surface of all parts of the leg, or restricted to one surface of, for example, the tarsus. These interneurones therefore bear a striking resemblance to two groups of spiking local interneurones in the adjacent segmental ganglion of the metathorax.
Localization of cytochrome oxidase in the mammalian spinal cord and dorsal root ganglia, with quantitative analysis of ventral horn cells in monkeys
Authors: Wong‐Riley M. T. T. , Kageyama G. H. 
Published: January 2005

AbstractThe spinal cord and dorsal root ganglia of mice, rats, cats, squirrel monkeys, and macaque monkeys were examined at both the light and electron microscopic levels for cytochrome oxidase activity. A similar histochemical pattern prevailed in all of the species examined. While the spinal gray exhibited a heterogeneous but consistent distribution of the enzyme, the white matter was only lightly stained. Highly reactive neurons were either singly scattered or aggregated into discrete clusters. The dorsal nucleus of Clarke, the lateral cervical nucleus (cat), the intermediolateral cell columns of the thoracic and upper lumbar levels, and selected groups of ventral horn neurons formed moderate to darkly reactive cell clusters, whereas fusiform and multipolar cells of Waldeyer in the marginal layer, small fusiform neurons in the ventral gray, funicular cells in the white matter, and ventral horn neurons of varying sizes tended to stand out against the neuropil as singly reactive neurons. At the electron microscopic level, reactive neurons were characterized by a greater packing density of darkly reactive mitochondria, while lightly reactive ones had fewer mitochrondria, most of which showed very little reaction product. Reactive mitochondria were also found in the neuropil, mainly in dendritic profiles and some axon terminals. Glial cells, in general, were not very reactive.Ventral horn neurons from three macaque monkeys were measured for somatic areas and optical densities of cytochrome oxidase reaction product. A total of 1,770 neurons from representative sections of the cervical, thoracic, lumbar, and sacral cords of these animals were analyzed. The results indicated that the distribution of cell sizes as well as optical densities at every level of the cord fell on a continuum. Analysis of the regression coefficients revealed that the slopes were negative for all levels, indicating that there was a general inverse relationship between cell size and optical densities. However, there were representations of dark, moderate, and lightly reactive neurons in all three size categories (large, medium; and small). Thus, the level of oxidative metabolism of ventral horn neurons cannot be correlated strictly with size, but it is likely to reflect their total synaptic and spontaneous activities.Neurons of the dorsal root ganglia likewise exhibited heterogeneous distribution of cell sizes and levels of enzyme reactivity, while satellite cells, in general, were only lightly reactive. As in the case of the ventral horn, representatives of dark, moderate, and light levels of reactivity occurred in every size category of neurons. The finding was also confirmed at the electron microscopic level. The metabolic variations among ganglionic neurons again suggest a functional subclassification based mainly on their total energy demands, which should be related closely to their combined intrinsic and synaptic activities.
Sprouting of serotoninergic afferents into striatum after dopamine‐depleting lesions in infant rats: A retrograde transport and immunocytochemical study
Authors: Snyder Abigail M. , Zigmond Michael J. , Lund Raymond D. 
Published: January 2005

AbstractIntraventricular injections of 6‐hydroxydopamine in 3‐day‐old rats resulted in the near‐total loss of tyrosine‐hydroxylase‐immunoreactive processes in the striatum when examined 2‐6 months later. This destruction of dopamine (DA) afferents was accompanied by an increase in the density of serotonin (5‐HT)‐immunoreactive fibers in the striatum. The hyperinnervation was most striking in the rostral striatum, an area containing few 5‐HT‐immunoreactive fibers in control rats. Retrograde tracing, with either horseradish peroxidase or rhodamine‐labelled microspheres, indicated a significant increase in the number of neurons projecting to the rostral striatum from the dorsal raphe nucleus of lesioned animals. The increase was largely confined to the rostral extent of the dorsal raphe, and overlapped the distribution of cells labelled after injections of HRP into caudal striatum of control and lesioned animals. In sections additionally processed for immunocytochemistry, 80–90% of retrogradely labelled raphe neurons in both groups of animals were found to be 5‐HT‐immunoreactive. None of changes encountered in infant‐lesioned rats were observed 2–4 weeks after 6‐HDA was given to adult animals. These findings demonstrate that removal of DA afferents during development leads to an enlargement of the serotoninergic projection from the raphe nucleus to the striatum.