bluuebunny/crossref_metadata_2025_split huggingface dataset:
Connections of the dorsal nucleus of the lateral lemniscus: An inhibitory parallel pathway in the ascending auditory system?
Authors: Shneiderman Amiram , Oliver Douglas L. , Henkel Craig K. 
Published: January 2005

AbstractThis study examines the dorsal nucleus of the lateral lemniscus (DNLL) and its afferent and efferent connections. In Nissl‐stained material, DNLL has three parts: dorsal, ventral, and lateral. Although each part contains neurons with similar Nissl patterns, the subdivisions may be distinguished by the size, shape, and orientation of the cells. The lateral DNLL contains a mixture of DNLL neurons and cells from the sagulum.Afferent connections to DNLL were investigated with anterograde axonal transport techniques. Bilateral inputs to DNLL arise from the anteroventral cochlear nucleus and lateral superior olive, while unilateral inputs are provided by the ipsilateral medial superior olive and the contralateral DNLL. The inputs appear to have a tonotopic organization. Afferent fibers to DNLL form horizontal bands that are continuous both mediolaterally and rostrocaudally. All parts of DNLL do not share the same inputs, and a medial‐to‐lateral gradient in the labeling of some pathways is evident.To study the efferent connections of DNLL, both retrograde and anterograde axonal transport techniques were used. The DNLL projects to the inferior colliculus and the contralateral DNLL. The topography of these projections suggests that areas of similar tonotopic organization are connected. In the inferior colliculus, the projection is heaviest to the central nucleus and extends to the adjacent dorsal and caudal cortex, the rostral pole nucleus, and the ventrolateral nucleus. Axons from DNLL terminate along the fibrodendritic laminae of the central nucleus as bands that are prominent on the contralateral side, whereas those on the ipsilateral colliculus are more diffuse.The afferent and efferent connections of DNLL constitute a multisynaptic pathway, parallel to the other ascending pathways to the inferior colliculus. The other ascending pathways include the direct pathways from the cochlear nucleus to the inferior colliculus and the indirect pathways via the superior olivary complex. Ascending pathways are discussed as to their relationship to the subdivisions of the inferior colliculus, the laterality of their projections, and their banding patterns in the central nucleus. In contrast to the excitatory pathways to the inferior colliculus, the neurons in DNLL may use GABA as a neurotransmitter. Axons from the DNLL terminate in the inferior colliculus as bands that could have a unique inhibitory function. Thus, the multisynaptic, DNLL pathway may provide feed‐forward inhibitory inputs to the inferior colliculus, bilaterally, and to the contralateral DNLL.
Morphology of physiologically identified second‐order vestibular neurons in cat, with intracellularly injected HRP
Authors: Ohgaki Tohru , Curthoys Ian S. , Markham Charles H. 
Published: January 2005

AbstractThe morphology of horizontal canal second‐order type I neurons was investigated by intracellular staining with horseradish peroxidase (HRP) and three‐dimensional reconstruction of the cell bodies and axons.Axons penetrated in and around the abducens nucleus were identified as originating from type I neurons by their characteristic firing pattern to horizontal rotation and by their monosynaptic response to stimulation of the ipsilateral vestibular nerve. A total of 47 type I neurons were stained. The cell bodies were located in the rostral portion of the medial vestibular nucleus (MVN) and were large or medium sized and had rather elongated shapes and rich dendritic arborizations. The neurons were divided into two groups: those which projected to the contralateral side of the brain stem (type Ic neurons) and those which projected to the ipsilateral side of the brainstem (type Ii neurons).All stem axons of type Ic neurons crossed the midline and bifurcated into rostral and caudal branches in the contralateral medial longitudinal fasciculus (MLF). Two or three collaterals arising close to this bifurcation distributed terminals in a relatively wide area in the contralateral abducens nucleus. Some of these collaterals projected further to the contralateral MVN and thus are vestibular commissural axons. Some of the rostral and caudal stem axons had collaterals which projected to the contralateral nucleus prepositus hypoglossi (PH), nucleus raphe pontis, or medullary reticular formation.There were at least six classes of type Ii neurons, most of which distributed to a relatively limited region in the ipsilateral abducens nucleus and they were categorized according to their future projections into the following categories: (A) no further collaterals beyond the abducens nucleus; (B) collaterals in the abducens nucleus and a branch descending and terminating in ipsilateral PH; (C) projected to the abducens nucleus, PH, and an area rostral to the abducens nucleus; (D) projected to the abducens nucleus and to ipsilateral reticular formation rostral and caudal to the abducens nucleus; (E) collaterals in the abducens nucleus and a thick caudal stem axon entering and descending in ipsilateral MLF; (F) a thick caudal stem axon entering and descending in ipsilateral MLF and no collaterals to the abducens nucleus. Some type Ii neurons also had recurrent collaterals which projected back to the ipsilateral MVN; these may inhibit type II neurons during ipsilateral rotation.
Changes with age in the morphology of the cochlear nerve in rats: Light microscopy
Authors: Hoeffding Virginia , Feldman Martin L. 
Published: January 2005

AbstractCochlear nerve morphology was examined in a series of rats ranging in age from young adulthood to advanced age in order to assess the extent of fiber loss and the nature of degenerative changes with age. The animals were perfused via the aorta with mixed aldehydes. Blocks including the cochlear nerves were removed, embedded in Araldite, and sectioned in a plane transverse to the longitudinal axis of the nerve. Analysis of the material included counts of normal and degenerating fibers and of glial cells, maps of fiber packing densities, and measurements of the cross‐sectional area of the nerve.The median number of normal fibers in the young adult animals (2‐3 months) was 21,218. This number was reduced by 21% at 26.5 months and by 24% in the oldest group (35‐36 months). The number of degenerating myelin sheaths was first seen to be significantly increased at 6 months, reached a peak at 26.5 months, and declined at 35‐36 months. There was an age‐related increase in the cross‐sectional area of the nerve, amounting to about 60% at 26.5 months and to about 50% at 35–36 months. Fiber packing density decreased evenly with age over the area of the nerve. The increased cross‐sectional area and decreased fiber packing density appeared to be related to increases in the thickness of myelin sheaths and in the area occupied by interneural elements.
Markers shared between dorsal root and enteric ganglia
Authors: Kirchgessner A. L. , Dodd J. , Gershon M. D. 
Published: January 2005

AbstractAlthough the bowel is known to contain intrinsic primary afferent neurons with mucosal projections these cells have not been identified. The current study was undertaken to determine whether carbohydrate differentiation antigens or enzymatic markers common to primary sensory neurons could be found in enteric neurons. Subpopulations of sensory neurons of rat dorsal root ganglia (DRG) can be identified by the immunocytochemical detection of lactoseries and globoseries carbohydrate differentiation antigens with monoclonal antibodies (MAbs) and by the histochemical demonstration of carbonic anhydrase (CA)‐ or fluoride‐resistant acid phosphatase (FRAP) activities; therefore, these markers, and their coincident expression with neuropeptides, were studied in neurons of the rat small intestine. Subsets of enteric neurons were demonstrated by a MAb (1B2/1B7) recognizing ≥ 45%, and by a MAb (α‐SSEA‐1) recognizing ≤ 0.1 %, of DRG neurons, as well as by CA, but not FRAP activity. 1B2/1B7 + neurons were found in both the submucosal (∑46% of neurons) and myenteric plexuses (∼2% of neurons). Submucosal 1B2/1B7+neurons with mucosal projections also displayed vasoactive intestinal polypeptide (VIP) and neuropeptide Y (NPY) but not substance P (SP) or calcitonin‐gene‐related peptide (CGRP) immunoreactivities. SSEA‐1+neurons were only found in the myenteric plexus, did not project to the mucosa (and thus are unlikely to be primary afferents), and were SOM+or ENK+but VIP−and NPY−. CA activity was intense in ∼39% of the neurons of the submucosal plexus and in mucosal nerve fibers. Some (∼20%) of the submucosal CA neurons were also CGRP+, but VIP−and NPY−; therefore, MAb 1B2/1B7 and CA activity mark different nonoverlapping sets of submucosal neurons. Following the neonatal administration of capsaicin (50 mg/kg), 1B2/1B7 immunoreactivity was lost from all submucosal neurons; however, VIP immunoreactivity was not depleted from the cell bodies. Although it cannot yet be concluded that the MAb 1B2/1B7 or CA markers demonstrate the intrinsic sensory neurons of the gut, the presence in the bowel of both is consistent with the supposition that sensory neurons related to those of DRG are also found in the intestine. The functional and possible developmental significance of this relationship remains to be defined.
Development of spinocerebellar afferents in the clawed toad, Xenopus laevis
Authors: van der Linden J. A. M. , ten Donkelaar H. J. , de Boer‐van Huizen R. 
Published: January 2005

AbstractThe development of spinocerebellar projections in the clawed toad, Xenopus laevis, was studied with horseradish peroxidase as an anterograde and retrograde tracer. Early in development cells of origin of spinocerebellar projections were found, contralaterally, in or close to the medial motor column. In older tadpoles ipsilaterally projecting spinal neurons were also labeled from the cerebellum. These are virtually indistinguishable from the large primary motoneurons that occupy a very similar position in the spinal cord. Most of the labeled spinal cells were found in the thoracic spinal cord; they lie halfway between the brachial and lumbar secondary motor columns. Surprisingly, no primary spinocerebellar projection arising from dorsal root spinal ganglion cells could be demonstrated in X. laevis tadpoles and adult toads. Therefore, fibers in the cerebellum that were labeled anterogradely from the spinal cord can be expected to originate exclusively from the secondary spinocerebellar tract cells. These fibers appear to cross the cerebellum in or at the border of the granular layer.The present data suggest that in X. laevis early in the development of the cerebellum a distinct secondary spinocerebellar projection is already present, originating in neurons that can be compared with the “spinal border cells” in mammals. The relative sparseness of this secondary spinocerebellar projection and the apparent absence of primary spinocerebellar afferents probably indicate that spinocerebellar pathways are only of minor importance in X. laevis. The possibility remains, however, that the expansion of the secondary spinocerebellar pathway only starts when metamorphosis has been completed.
Localization of putative GABAergic neurons in the larval tiger salamander retina by immunocytochemical and autoradiographic methods
Authors: Yang Chen‐Yu , Yazulla Stephen 
Published: January 2005

AbstractPutative GABAergic neurons in the larval tiger salamander retina were localized by a comparative analysis of glutamate decarboxylase immunoreactivity (GAD‐IR), GABA‐like immunoreactivity (GABA‐IR), and high‐affinity 3H‐GABA uptake at the light microscopical level. Preliminary data showed that all GAD‐IR neurons were double labeled for GABA‐IR. However, because the weak somatic labeling with GAD‐IR, we could not determine if the converse were true. Neurons commonly labeled with GABA‐IR and 3H‐GABA uptake include horizontal cells, type I (outer) and type II (inner) bipolar cells, type I (inner) and type II (outer) amacrine cells, and cell bodies in the ganglion cell layer (GCL). In addition, interplexiform cells were identified with GABA‐IR. The presence of GABA‐IR ganglion cells was indicated by GABA‐IR fibers in the optic fiber layer and optic nerve as well as by a GABA‐IR cell in the GCL that included a labeled axon. The percentage of labeled somas in the inner nuclear layer (INL) compared to all cells in each layer was similar for the two methods: 30% in INL 1 (outer layer of somas), 15% in INL 2 (middle layer), 43–52% in INL 3 (inner layer), and about 21–26% in the GCL. Labeled processes were found in three bands in the inner plexiform layer, with the densest band located in the most proximal part. Postembedding labeling of 1‐μm Durcupan resin sections for GABA‐IR showed the same general pattern as obtained with 10‐μm cryostat sections, with additional staining, however, of type II (inner) bipolar cell Landolt's clubs. Extensive colocalization of labeling was indicated, and we conclude that GABA‐IR can serve as a valid and reliable marker for GABA‐containing neurons in this retina and suggest that GABA serves as a transmitter for horizontal cells, several types of amacrine cell, a type of interplexiform cell, and perhaps a small percentage of type I and type II bipolar cells and ganglion cells.
Sensory innervation of the hairs of the rat hindlimb: A light microscopic analysis
Authors: Millard Catherine L. , Woolf Clifford J. 
Published: January 2005

AbstractThe sensory innervation of the hair follicles of the furry skin of the rat hindlimb has been investigated by using the Winkelmann silver technique to stain peripheral axons and their terminals. This technique was found to stain only large‐ and medium‐sized dorsal root ganglion cells and all laminae of the dorsal horn except lamina II, and therefore it is likely that, while A beta and A delta afferent fibres in the skin are stained, C fibres are not. Small vellus hairs were the commonest type of hair on the hindlimb particularly above the ankle. Many were not innervated. Those that were had lanceolate terminals arranged as palisades parallel to the hair shaft with circumferential presumptive Ruffini piloneural complexes and free nerve endings external to this. Circumferential innervation patterns without palisades were not uncommon but palisades without circumferential fibres were rare. Guard hairs which varied considerably in size were the next commonest hair type. Considerably more of these were innervated, by three‐to‐15 afferents forming both palisades of ten‐to‐30 lanceolate terminals and circumferential terminals. Both the innervated vellus and guard hairs had an associated vertical fibre projecting toward the epidermis. Tylotrichs, the largest hairs on the hindlimb, were rare (1–2%) and were only found above the ankle, but all were densely innervated by many axons. A prominent single nerve contributed to an annular complex by forming a bilaminar arrangement of lanceolate and circumferential terminals within the outer connective tissue sheath. Each tylotrich had an associated Merkel cellneurite complex (haarscheiben).Differences in the distribution, innervation density, and phase in the growth cycle of the different hair types were found for skin from different regions of the hindlimb, which, together with the extent of the polyneuronal innervation of most follicles, has important implications for the processing by the somatosensory system of the afferent input generated by brushing hairs.
Behavioral and anatomical correlates of immunologically induced rejection of nigral xenografts
Authors: Carder Renee K. , Snyder‐Keller Abigail M. , Lund Raymond D. 
Published: January 2005

AbstractCell suspensions derived from the ventral mesencephalon of CD‐1 mice were unilaterally transplanted into the striatum of neonatal Sprague‐Dawley rats that had been bilaterally dopamine depleted. Thirty‐eight percent of the grafts survived. Tyrosine‐hydroxylase‐immunoreactive neurons within the transplant innervated the host striatum with a dense fiber plexus. The grafts appeared to exert some degree of functional control over motor behavior in that these animals made contralateral rotations in response to amphetamine and tail pinch. In order to provide additional evidence that the motor behavior is associated with the transplant itself, the graft was removed. This was achieved by using a mouse skin graft to provoke an immunological response against the transplanted neural tissue. The immunological response resulted in the specific loss of the transplant with little or no damage to the surrounding neural tissue. The amount of rotation observed after tail pinch and amphetamine injection was severely affected by neural graft rejection. The loss of turning was associated most directly with the loss of tyrosine hydroxylase immunoreactivity within the transplant rather than with the massive reduction of tyrosine‐hydroxylase‐positive fibers in the ipsilateral host striatum. These data suggest that dopamine cells in mouse nigral grafts play an essential role in eliciting rotational behavior in neonatally dopamine depleted rats. They also show the value of skin grafting as a technique for specifically removing neural xenografts.
Axons added to the regenerated visual pathway of goldfish establish a normal fiber topography along the age‐axis
Authors: Bernhardt Robert , Easter Stephen S. , Raymond Pamela A. 
Published: January 2005

AbstractThroughout a goldfish's life, new generations of ganglion cells are added on the retinal margin and their axons extend centrally to occupy predictable positions in the retinotectal pathway, adjacent to their predecessors and subjacent to the pia. The stacking of successive generations of axons defines the age‐axis of the pathway. This study examined whether an ordered array of predecessor axons is a prerequisite for the patterned growth of new axons. One optic nerve was crushed intraorbitally and the fish was injected with 3H‐thymidine to label the proliferating cells on the retinal margin. The ring of 3H‐thymidine‐labeled cells separated retina that was present at the time of nerve crush (inside the ring) from new retina added afterward (outside). After a period of 14–16 months postcrush, both tectal lobes received two punctate applications of horseradish peroxidase (HRP), one in the central and the other in peripheral tectum, to retrogradely label contralateral retinal ganglion cell bodies and their axons.The pattern of HRP labeling from the control tectum confirmed earlier work: axons on the central tectum had somata in the central retina, and axons on the peripheral tectum had somata in the peripheral retina. The labeled cells and axons were both in predictable patterns. The somata that were backfilled from applications to the center of the experimental tectum lay inside the radioactive ring and had therefore regenerated their axons. The patterns of their labeled axons in the optic pathway and of their somata in the retina were typical of the regenerated condition as described in earlier studies. The somata backfilled from the periphery of the experimental tectum were outside the radioactive ring and had been added after the optic nerve crush. The patterns of their labeled axons and somata were comparable to the normal pattern. These observations indicate that new axons do not depend on an ordered array of predecessors to reestablish normal order along the age‐axis of the pathway.
Topography and cytoarchitecture of the motor nuclei in the brainstem of salamanders
Authors: Roth Gerhard , Nishikawa Kiisa , Dicke Ursula , Wake David B. 
Published: January 2005

AbstractThe organization of the motor nuclei of cranial nerves V (including mesencephalic nucleus), VI, VII, IX, and X is described from HRP‐stained material (whole mounts and sections) for 25 species representing five families of salamanders, and the general topology of the brainstem is considered. Location and organization of the motor nuclei, cytoarchitecture of each nucleus, and target organs for nuclei and subnuclei are described. The trigeminal nucleus is separated distinctly from the facial and abducens nuclei and consists of two subnuclei. The abducens nucleus consists of two distinct subnuclei, one medial in location, the abducens proper, and the other lateral, the abducens accessorius. The facial nucleus has two subnuclei, and in all but one species it is posterior to the genu facialis. The facial nucleus completely overlaps the glossopharyngeal nucleus and partially overlaps that of the vagus. In bolitoglossine plethodontid salamanders, all of which have highly specialized projectile tongues, the glossopharyngeal and vagus nuclei have moved rostrally to overlap extensively and intermingle with the anterior and posterior subnuclei of the facial nerve. In the bolitoglossines there is less organization of the cells of the brainstem nuclei: dendritic trunks are less parallel and projection fields are wider than in other salamanders. Some aspects of function and development are discussed; comparisons are made to conditions in anurans; and phylogenetic implications are considered.
Central projections of the rat radial nerve investigated with transganglionic degeneration and transganglionic transport of horseradish peroxidase
Authors: Ygge Jan 
Published: January 2005

AbstractTransganglionic degeneration and transganglionic transport of HRP were used for investigation of the spinal cord and brainstem projections from the superficial, cutaneous (SR) and deep, muscular (DR) branches of the radial nerve. The HRP study included a numerical and size analysis of labelled dorsal root ganglion (DRG) cells.In degeneration experiments the SR nerve was found to project somatotopically to laminae III–IV, but degeneration was also found in lamina I and inconsistently in lamina II. Transection of the DR nerve was found to give rise to a small amount of degeneration, which in “sham” operations was established to result from the skin injury during dissection of the DR nerve.With the HRP method, the SR nerve was found to project somatotopically to laminae I–IV, whereas the DR nerve projected more diffusely to the medial part of laminae V–VII. HRP application to the SR and DR nerves resulted in labelling of a mean of 1,024 and 310 DRG cells, respectively. These labelled neurons had a median cell area of 381 and 562 μm2 for the SR and DR nerves, respectively, and both small and large cells were labelled in both types of experiments. In the lower brainstem, projections from the SR nerve were found only in the ipsilateral dorsal part of the main cuneate nucleus (MCN) with both methods. Brainstem projections from the DR nerve that were found only with the HRP method were found in the ipsilateral ventral part of the MCN together with a projection to the ipsilateral external cuneate nucleus. No projections were found to the central cervical nucleus.The present results indicate that cutaneous compared to muscular primary sensory neurons are much more prone to react with transganglionic degeneration after peripheral nerve transection. Furthermore, in the rat the SR nerve projects somatotopically, whereas the DR nerve does not. Both nerve branches are connected to small and large spinal ganglion cells, although the median cell area is larger in muscular neurons.