bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regular mosaics of large displaced and non‐displaced ganglion cells in the retina of a cichlid fish
Authors: Cook Jeremy E. , Becker David L. 
Published: January 2005

AbstractLarge retinal ganglion cells in the tilapid cichlid fish Oreochromis spilurus (standard length 15–54 mm) were filled with horseradish peroxidase and studied in flatmounts. Three types, with distinct patterns of dendritic stratification, formed spatially independent, nonrandom mosaics.One type (about 0.3% of all ganglion cells) resembled the outer (off) alpha cells of mammals. They were very large, with thick primary dendrites and large, sparsely branched planar trees in the outer part of the inner plexiform layer (IPL). About 300 were arrayed regularly across each retina, their exact number and spacing depending on its size. Their somata were often displaced into the IPL, even where neighbours in the mosaic were orthotopic. Another type (0.8%) resembled the inner (on) alpha cells of mammals. These had slightly smaller somata that were never displaced and smaller trees in the middle layers of the IPL. About 800 were arrayed uniformly and regularly across each retina. A rarer type (0.06–0.08%) had two planar trees: one forming a coarse mosaic in the outer part of the inner plexiform layer (co‐planar with the trees of outer alpha‐like cells) and another in the outer plexiform layer. These “biplexiform” cells were smaller and rounder than alpha‐like cells and always displaced. The dendrites were finer and less tapered. Cells in which we could identify an outer plexiform tree failed to cover the retina completely, but were nonrandomly distributed.We draw three main conclusions: (1) some nonmammalian vertebrates have separate inner and outer mosaics of large ganglion cells like those of mammals, (2) the vertical displacement of ganglion cell somata can vary widely within a single mosaic and may thus be functionally irrelevant, and (3) biplexiform ganglion cells exist in fish but differ in morphology from the biplexiform types described in some other vertebrates.
A collagen‐based nerve guide conduit for peripheral nerve repair: An electrophysiological study of nerve regeneration in rodents and nonhuman primates
Authors: Archibald Simon J. , Krarup Christian , Shefner Jeremy , Li Shu‐Tung , Madison Roger D. 
Published: January 2005

AbstractWhen a peripheral nerve is severed and left untreated, the most likely result is the formation of an endbulb neuroma; this tangled mass of disorganized nerve fibers blocks functional recovery following nerve injury. Although there are several different approaches for promoting nerve repair, which have been greatly refined over recent years, the clinical results of peripheral nerve repair remain very disappointing. In this paper we compare the results of a collagen nerve guide conduit to the more standard clinical procedure of nerve autografting to promote repair of transected peripheral nerves in rats and nonhuman primates.In rats, we tested recovery from sciatic nerve transection and repair by (1) direct microsurgical suture, (2) 4 mm autograft, or (3) entubulation repair with collagen‐based nerve guide conduits. Evoked muscle action potentials (MAP), were recorded from the gastrocnemius muscle at 4 and 12 weeks following sciatic nerve transection. At 4 weeks the repair group of direct suture demonstrated a significantly greater MAP, compared to the other surgical repair groups. However, at 12 weeks all four surgical repair groups displayed similar levels of recovery of the motor response.In six adult male Macaca fascicularis monkeys the median nerve was transected 2 cm above the wrist and repaired by either a 4 mm nerve autograft or a collagen‐based nerve guide conduit leaving a 4 mm gap between nerve ends. Serial studies of motor and sensory fibers were performed by recording the evoked MAP from the abductor pollicis brevis muscle (APB) and the sensory action potential (SAP) evoked by stimulation of digital nerves (digit II), respectively, up to 760 days following surgery. Evoked muscle responses returned to normal baseline levels in all cases. Statistical analysis of the motor responses, as judged by the slope of the recovery curves, indicated a significantly more rapid rate of recovery for the nerve guide repair group. The final level of recovery of the MAP amplitudes was not significantly different between the groups. In contrast, the SAP amplitude only recovered to the low normal range and there were no statistically significant differences between the two groups in terms of sensory recovery rates.The rodent and primate studies suggest that in terms of recovery of physiological responses from target muscle and sensory nerves, entubulation repair of peripheral nerves with a collagen‐based nerve guide conduit over a short nerve gap (4 mm) is as effective as a standard nerve autograft. Furthermore, preliminary results show that entubulation repair with this material can support axon regeneration and maturation over a nerve gap distance of at least 15 mm.
Evidence for the presence, synthesis, immunoreactivity, and uptake of GABA in the nervous system of the snail Helisoma trivolvis
Authors: Richmond J. E. , Bulloch A. G. M. , Bauce L. , Lukowiak K. 
Published: January 2005

AbstractIn the present study several techniques were employed to test the hypothesis that gamma‐aminobutyric acid (GABA) is a neurotransmitter in the central nervous system (CNS) of the pond snail Helisoma trivolvis (Mollusca, Pulmonata). First, by using chromatographic techniques, the presence of GABA and its differential distribution among the ganglia constituting the CNS was demonstrated. Second, de novo synthesis of 3H‐GABA from 3H‐glutamate was shown by the CNS. Levels of both endogenous and newly synthesized GABA were greatest in the buccal, cerebral, and pedal ganglia. Third, indirect immunohistochemistry of wholemounts revealed a central network of GABA‐like immunoreactive neurons. With the possible exceptions of two pairs of fibers in nerve trunks, all projections from GABA‐immunoreactive neurons were confined to the CNS, suggesting a predominantly central role for GABA. Stained neurons were found on the dorsal surface of the buccal ganglia and throughout the cerebral and pedal ganglia. No GABA‐immunoreactive cell bodies were observed in the parietal, pleural, or visceral ganglia. Finally, uptake of 3H‐GABA was examined autoradiographically in sectioned ganglia. A pattern of radiolabelled cells was observed that closely resembled the distribution of GABA‐immunoreactive neurons.The data described above fulfill several criteria necessary to establish GABA as a transmitter in the nervous system of Helisoma. Taken together with previously obtained pharmacological evidence demonstrating that GABA acts on Helisoma central neurons, GABA is considered to be a strong candidate for a neurotransmitter in Helisoma.
Prenatal specification of callosal connections in rhesus monkey
Authors: Schwartz Michael L. , Goldman‐Rakic Patricia S. 
Published: January 2005

AbstractAnatomical tracing and quantitative techniques were used to examine the tempo and pattern of maturation for callosal projection neurons in the monkey prefrontal cortex (PFC) during fetal and postnatal development. Nineteen monkeys were injected with retrograde tracers (fluorescent dyes, horseradish peroxidase conjugated to wheat germ agglutinin [WGA‐HRP] or HRP crystals) at various ages between embryonic day 82 (E82) and adulthood. The size of injection sites was varied in fetal, newborn, and adult cases.In adults, labeled neurons were found in greatest density in the homotopic cortex of the opposite hemisphere and considerable numbers were also observed in a constellation of heterotopic areas including the medial and lateral orbital cortex, the dorsomedial convexity, and the pregenual cortex. The majority of labeled neurons were consistently concentrated in the lower half of layer III in all areas. In cases with large injection sites, callosal neurons of layer III formed a continuous and uninterrupted band that extended over the entire lateral surface of the prefrontal cortex spanning both homotopic and heterotopic areas. In contrast, in cases with small injection sites, the labeling of layer III neurons exhibited discontinuities.Between embryonic ages E82 and E89, injections limited to the cortical layers labeled only a small number of neurons in the opposite hemisphere, indicating that few callosal axons have invaded the cortex by this age. However, by E111 comparable injections labeled a large number of callosal neurons and many features of their distribution were adult‐like. The number and constellation of cytoarchitectonic areas that were labeled in the frontal cortex of the opposite hemisphere were the same as in adults and the majority of callosal neurons were found in supragranular layer III. Finally, in fetal animals beyond E111, labeled neurons extended as a nearly unbroken band over a wide expanse of the dorsolateral PFC, resembling the pattern seen in adult monkeys with large injections.The conclusion we draw from these results, together with our earlier findings (Schwartz and Goldman‐Rakic: Nature 299:154, 1982), is that callosal neurons whose axons enter the cortical layers of the primate prefrontal cortex achieve their mature laminar and areal distribution prior to birth and do so largely by cumulative processes.
Development of the calcium‐binding proteins parvalbumin and calbindin in monkey striate cortex
Authors: Hendrickson A. E. , van Brederode J. F. M. , Mulligan K. A. , Celio M. R. 
Published: January 2005

AbstractThe development of immunoreactivity for the calcium‐binding proteins parvalbumin (PV) and calbindin‐D28K (Cal) was studied in Macaca nemestrina striate, cortex from fetal (F) 60 days to postnatal (P) 5 + years. We correlated changes in PV and Cal staining patterns with the well‐documented developmental sequence for primate striate cortex neuron generation and maturation, synaptogenesis, and thalamocortical axon interactions in an attempt to deduce a functional role for these proteins.Our major finding is that Cal and PV have diametrically opposed developmental patterns except in layer 1. At F60 days both are present only in neurons of layer 1 and the number of labeled cell bodies and processes increases up to F125 days. Almost all Cal+ and PV+ cells in layer 1 disappear by P12 weeks. Cal is present by F113 days in pyramidal and stellate neurons, particularly layers 4–6. The number and staining density of cells in layers 2–6 increases up to birth and then both decline by P9–12 weeks. Supragranular layers show a second increase in Cal labeling from P20–36 weeks, and then there is a slow decline to the adult pattern which is reached by P1–2 years. Cell bodies in layers 4A, 4Cα, and deep 4Cβ are heavily Cal+ during pre‐and early post‐natal periods, but upper 4Cβ remains unlabeled.PV is not seen until F155–162 days in layers 2–6. Large stellate and a few pyramidal cells appear first in layers 5/6 and 4Cα, but PV + stellate neurons are found in all layers except 4Cβ by P6 weeks. Layer 4Cβ contains a few PV+ cell bodies at P3 weeks, and light neuropile staining at P6 weeks, but then PV labeling rapidly increases so that by P12 weeks the density of 4Cβ exceeds that of 4Cα. Striate cortex has an adult pattern of cell number and neuropile density by P20 weeks.These developmental patterns suggest that the highest density of Cal cell body staining does not correlate with synaptogenesis, or the postnatal critical period of visually driven, binocular interactions. Rather Cal appears when lateral geniculate axons arrive in cortex, persists over the entire span of thalamocortical interactions, and disappears during the decline of cortical plasticity. The appearance of PV is highly correlated with the onset of complex visually driven activity at birth, while both the number of PV+ cell bodies and the density of PV+ neuropile reach adult levels coincident with the completion of thalamocortical connections.
Distribution of 125I‐galanin binding sites, immunoreactive galanin, and its coexistence with 5‐hydroxytryptamine in the cat spinal cord: Biochemical, histochemical, and experimental studies at the light and electron microscopic level
Authors: Arvidsson Ulf , Ulfhake Brun , Cullheim Staffan , Bergstrand Anita , Theodorsson Elvard , Hökfelt Tomas 
Published: January 2005

AbstractThe distribution of galanin‐like immunoreactivity (GAL‐LI) in the spinal cord of the cat was studied by use of indirect histochemistry and the peroxidase‐antiperoxidase (PAP) technique. In the ventral horn GAL‐immunoreactive (IR) axonal fibers and terminals were most frequent in the ventral part of the motor nucleus. The GAL‐IR axons also contained 5‐hydroxytryptamine (5‐HT)‐LI, and they disappeared after spinal cord transection. It was concluded that these GAL‐IR fibers belong to the serotoninergic bulbospinal pathway. In the medulla oblongata from normal cats, scattered GAL‐IR cell bodies were encountered within the nucleus raphe obscurus and nucleus raphe pallidus. Electron microscopic observations revealed that the fine structure of the GAL‐IR axonal boutons in the motor nucleus was similar to that of 5‐HT‐IR boutons with a varying number of immunoreactive large dense core vesicles. The postsynaptic element in all cases studied was a dendrite.A dense GAL‐IR axonal plexus was found in the superficial laminae I‐II of the dorsal horn. Coexistence was found between the GAL‐ and substance P‐LI in fibers within the dorsal horn plexus. Spinal cord transection did not alter the pattern of GAL‐LI in the dorsal horn, while the vast majority of GAL‐IR axonal swellings disappeared following dorsal root sectioning. Electron microscopic observations in lamina II (substantia gelatinosa) revealed that the GAL‐IR axonal terminals could be divided into two main groups. One with small to medium‐sized axonal buttons formed synaptic contacts with both dendritic and axonal profiles. The other formed the central axon terminals of glomeruli, suggesting that GAL‐LI may be present in C‐type primary afferents. Numerous small GAL‐IR cell bodies were encountered in laminae II and III. GAL‐IR cell bodies were also observed in lamina X.The dorsal root ganglia contained a low but consistent number of small to medium‐sized GAL‐IR cell bodies, which all contained immunoreactive calcitonin gene‐related peptide (CGRP). Following peripheral sciatic nerve transection, the number and the labeling intensity of GAL‐IR cell bodies in the corresponding dorsal root ganglia showed a moderate increase.Radioimmunoassay revealed that the concentration of GAL‐LI increased along the rostrocaudal axis of the normal spinal cord, and was about three times higher in the dorsal than in the ventral regions. The concentration in the dorsal root ganglia was intermediate to those seen in the corresponding dorsal and ventral cord regions. Autoradiography showed a high density of 125I‐GAL binding sites in the superficial laminae of the dorsal horn throughout the spinal cord.
Morphogenesis of adrenergic cells in a frog parasympathetic ganglion
Authors: Heathcote R. David , Chen Aileen 
Published: January 2005

AbstractThe development of the parasympathetic cardiac ganglion of the frog Xenopus laevis was marked by the differentiation of a population of adrenergic small intensely fluorescent (SIF) cells. The neural crest contributes precursors for both SIF cells and the well‐studied cholinergic cardiac ganglion neurons; this situation provided an opportunity to determine whether morphogenesis of the two cell types was correlated. Accordingly, we examined the initial differentiation, developmental regulation, and territorial domain of cardiac SIF cells for comparison with their cholinergic neuron neighbors.Adrenergic SIF cells were present during the time when the first cholinergic precursors were becoming postmitotic. Although SIF cells were present first, cholinergic neurons differentiated almost 16 times faster during the first week of embryonic and larval development and outnumbered SIF cells at all subsequent stages. Nonetheless, the accumulation of both cell types were correlated, since the ratio of cholinergic neurons to SIF cells remained at approximately 10 to 1 up to adult life. Early in development, SIF cells and cholinergic neurons were clustered in the sinus venosus portion of the atrium. The asymmetric distribution of cholinergic neurons within the atrium was lost hut that of the SIF cells was maintained throughout life. These results identify relationships between the morphogenesis of two cell types in an autonomic ganglion and place constraints upon the cellular mechanisms that could produce the cells from their neural crest precursors.
Inhibition of axonal development after injection of neurofilament antibodies into a Xenopus laevis embryo
Authors: Szaro Ben G. , Grant Philip , Lee Virginia M.‐Y. , Gainer Harold 
Published: January 2005

AbstractThe ability to target specific cytoskeletal components in axons for disruption within intact developing embryos would provide a valuable tool for studying neuronal development. Neurofilaments are an attractive target for such an approach, because they are neuron specific and are expressed late in embryogenesis principally beginning during axon outgrowth. No pharmacological agents are currently available that disrupt neurofilaments without also affecting general development. One approach that has been used successfully to affect proteins in vivo is to inject specific antibodies into living cells. We employed this approach in Xenopus laevis embryos by injecting two antibodies directed against the middle molecular weight neurofilament protein (NF‐M) into a single blastomere of a two‐cell stage embryo. Injected antibodies could be detected for as long as 3.5 days in cells descended from the injected blastomere. Only cell bodies of neurons descended from anti‐NF‐M‐injected blastomeres contained abnormal accumulations of intermediate filament proteins, and peripheral nerve development was unilaterally retarded in these neurofilament antibody‐injected tadpoles. Such accumulations and peripheral nerve defects were not seen in neurons derived from uninjected blastomeres or from blastomeres injected with control antibodies. These data demonstrate the usefulness of specific antibodies to perturb neuronal development in intact frog embryos and, in addition, suggest a role for neurofilaments in axon elongation.
Epitopes located in spatially separate domains of each neurofilament subunit are present in parkinson's disease lewy bodies
Authors: Hill William D. , Lee Virginia M.‐Y. , Hurtig Howard I. , Murray John M. , Trojanowski John Q. 
Published: January 2005

AbstractSubcortical Lewy bodies are the pathological hallmark of idiopathic Parkinson's disease. This study sought to determine the extent to which each neurofilament subunit [low (NF‐L), mid (NF‐M), or high (NF‐H)] was present in Lewy bodies by using light, confocal, and electron microscopy. A battery of 37 antineurofilament antibodies, characterized as to subunit specificity, epitope domain, and phosphorylation status, was employed to probe substantia nigra Lewy bodies from 15 Parkinson's disease cases. All 37 antibodies labelled Lewy bodies. The epitopes recognized by these antibodies included those in the NF‐L rod and tail domains; the NF‐M head, rod, and tail domains, as well as epitopes within, and flanking, the multiphosphorylation repeat site; and the NF‐H rod domain and multiphosphorylation repeat sites. With these probes, nearly the entire length of each subunit could be demonstrated in Lewy bodies. However, the staining pattern of the Lewy bodies suggested that the tail domains of NF‐M and NF‐H were present in the periphery of the Lewy body core and in the Lewy body corona, but they appeared to be altered or missing in the center of the Lewy body core. In contrast, the head domain of NF‐M, the tail domain of NF‐L, and the rod domains of all three subunits are present throughout the Lewy body. These results strongly suggest that the entire extent of each neurofilament subunit is found in Lewy bodies but that the neurofilament subunits may be altered during the processing of these filaments into Lewy bodies.
Gracile projection to the cat medial accessory olive: Ultrastructural termination patterns and convergence with spino‐olivary projection
Authors: Molinari Helen H. , Starr Kathy A. , Sluyters Romuald N. 
Published: January 2005

AbstractThe caudal medial accessory subdivision of the inferior olive (cMAO) receives information from the hindlimb from both the gracile nucleus and the lumbosacral spinal cord. This study determined which elements in cMAO serve as the postsynaptic targets of the gracile projection and whether these elements also receive input from the lumbosacral spinal cord. Gracile axons were labeled in cats by anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP), visualized with tetramethylbenzidine. Convergence of gracile and lumbosacral axons was evaluated by labeling in the same animal, one pathway by WGA‐HRP and the other by degeneration.In cMAO, gracile axons synapse with equal probability on dendritic spines and distal dendritic shafts. This termination pattern contrasts markedly with that of other somatosensory inputs to the inferior olive and may account for the greater heterogeneity in responses to somatosensory stimuli displayed by neurons in cMAO. The distal dendritic shafts receiving gracile input were more likely than dendritic spines to receive convergent input from putative inhibitory synapses. The most likely source of these inhibitory synapses is the parasolitary nucleus, a structure that has been shown by others to receive input from the cerebellum. Thus the parasolitary nucleus may serve as an inhibitory relay between the cerebellum and cMAO.The dendritic spines in cMAO that receive input from the gracile nucleus often receive additional input from the lumbosacral spinal cord. This convergence of somatosensory axons on dendritic spines may provide a mechanism through which the unusually complex receptive fields of neurons in cMAO are generated.
Ultrastructural evidence that early synapse formation on central vestibular sensory neurons is independent of peripheral vestibular influences
Authors: Petralia R. S. , Gill S. S. , Peusner K. D. 
Published: January 2005

AbstractMigration and early differentiation of neurons of the tangential vestibular nucleus of the chick take place between embryonic days 5 and 8. In the absence of primary vestibular afferents (otocyst‐ablation), a previous light microscope study documented that early developmental events still occurred, but the neurons failed to complete differentiation and to survive. In order to understand why these neurons undergo normal early development, we have repeated the vestibular deafferentation paradigm followed by ultrastructural observations on these neuron.We found that the ultrastructural events associated with migration and differentiation in the deafferented tangential nucleus were essentially normal from 5 to 8 days. Most important, longitudinal fibers, presumably of central, nonvestibular origins, formed the first synapses at the same time and sequence as observed in normal embryos. Thus vestibular sensory neurons receive their first input from central fibers, initiating events in the formation of a central vestibular circuitry without the influence of peripheral vestibular fibers or endorga.