bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regeneration of axons from the adult rat optic nerve: Influence of fetal brain grafts, laminin, and artificial basement membrane
Authors: Hausmann Beate , Sievers Jobst , Hermanns Joachim , Berry Martin 
Published: January 2005

AbstractAfter transection of the optic nerve of adult rats, most of the axons in the proximal stump die and the surviving ones are unable to regenerate into the distal optic nerve. Since the fetal brain has an inherent capacity to regenerate axons, we investigated whether fetal (E16) target regions of optic axons (thalamus and tectum) transplanted to the completely transected optic nerve of adult rats would promote axon regeneration. In control operated rats, axon growth beyond the site of transection was restricted to a few fibers that grew irregularly within the connective tissue scar. By contrast, in grafted animals directed outgrowth of optic axons toward the transplant started at 6 days postoperation (p.o.) and reached its maximum 15 days p.o. and later, when numerous single optic fibers and small axon fascicles had grown toward and into the graft, where they formed arborizations and terminal varicosities. Regenerating optic axons were further advanced than GFAP‐positive strands of astroglia that emanated from the proximal optic nerve stump. Laminin immunoreactivity appeared at 6 days p.o. in the zone of reactive astroglia in the terminal part of the optic nerve stump. Later it showed a distribution complementary to the pattern of GFAP immunoreactivity, which it seemed to circumscribe. There was no unequivocal codistribution of laminin immunoreactivity with regenerating axons.In further experiments, target regions from different ontogenetic stages (E14 to neonate and adult) and nontarget regions (E16, cerebral cortex or spinal cord) were grafted to the optic nerve stump. With the exception of the adult grafts, all transplants had effects on axon regeneration comparable to those of E16 target regions. In order to test the effects of extracellular matrix molecules on axon regeneration, a basement membrane gel reconstituted from individual components of the Engelbreth‐Holm‐Sarcoma (EHS) sarcoma was implanted between proximal and distal optic nerve stumps. No axons were induced to regenerate by this matrix. Likewise, laminin adsorbed to nitrocellulose paper and implanted at the lesion site did not stimulate axon growth from the proximal optic nerve stump.These results indicate that fetal brain is able to induce and direct regrowth of axons from the optic nerve toward the graft across a substrate that is not composed of astroglia or basement membrane components like laminin. The directed growth of axons in the absence of a preformed substrate implies a chemotactic growth response along a concentration gradient mediated by neurotropic molecules released from the graft.
Fetal brain grafts rescue adult retinal ganglion cells from axotomy‐induced cell death
Authors: Sievers Jobst , Hausmann Beate , Berry Martin 
Published: January 2005

AbstractAfter intraorbital transection of the optic nerve of adult rats, 90% of the retinal ganglion cells die within 30 days. Since fetal brain extracts and cocultured fetal target regions support the survival of retinal ganglion cells in vitro (Nurcombe and Bennett: Exp. Brain Res. 44: 249–258, '81; McCaffery et al.: Exp. Brain Res. 48: 377–386, '82; Armson and Bennett: Neurosci. Lett. 38: 181–186, '83) we investigated whether cell death in the adult retina could be prevented by transplanting fetal (E16) thalamus and tectum to the proximal stump of the optic nerve of adult rats that was completely transected 2–3 mm behind the optic disc. Unoperated eyes contained 119,973 (±939, SEM) retinal ganglion cells, estimated from axon counts of the intact optic nerve. Of these, 11,601 (±1,857) remained in control operated eyes at 30 days postoperation while in the eyes of grafted rats, 35,086 (±2,278) retinal ganglion cells were counted. Thus, 23,485 (=22% of those normally dying after transection of the optic nerve) ganglion cells were rescued by the fetal grafts from cell death normally following axotomy.These results indicate that fetal target regions of retinal ganglion cells contain and/or produce neurotrophic molecules that promote the survival of adult axotomized retinal ganglion cells.
Morphological characterization of substance P‐like immunoreactive glomeruli in the superficial dorsal horn of the rat spinal cord and trigeminal subnucleus caudalis: A quantitative study
Authors: Ribeiro‐da‐silva A. , Tagari P. , Cuello A. C. 
Published: January 2005

AbstractThe aim of this work was to study the ultrastructural distribution of substance P–like immunoreactivity in laminae I and II of rat spinal cord and trigeminal subnucleus caudalis in relation to synaptic glomeruli. A bispecific monoclonal antibody directed against substance P and horseradish peroxidase was used, combining sensitive immunocytochemistry with preservation of fine ultrastructural detail. Some of the quantitative observations were carried out with an automated image analysis system.The study revealed that in lamina I of the spinal cord, almost all immunoreactive profiles counted were nonglomerular, and a considerable number of them contacted medium‐size or large dendrites or were in direct contact with other vesicle‐containing profiles. In ventral lamina II, 9.4% of the labeled axonal varicosities were central boutons of type I glomeruli (CI). They could be identified by their scalloped contour, number and types of peripheral profiles, reduced density of mitochondria, and localization in the dorsal horn. However, these immunoreactive glomerular CI boutons (14.1% of the total number of CI) differed statistically from the prevailing population of nonimmunoreactive CI, by being surrounded by less peripheral neuronal profiles, which established fewer synapses. In addition, they contained more than three dense‐core vesicles per central profile.In the trigeminal subnucleus caudalis laminae I and II, the substance P fibers and varicosities had a plexiform orientation at the light microscopic level, which contrasted with the mainly rostrocaudal orientation of the spinal cord's lamina II plexus. However, the main ultrastructural findings were similar.These results demonstrate that substance P–like immunoreactivity occurs in a large number of type I synaptic glomeruli with specific morphological features and reinforce the current concept that the substantia gelatinosa of the spinal cord and trigeminal subnucleus caudalis are homologous structures.
Role of commissural projections in the representation of bilateral auditory space in the barn owl's inferior colliculus
Authors: Takahashi Terry T. , Wagner Hermann , Konishi Masakazu 
Published: January 2005

AbstractThe central nucleus of the barn owl's inferior colliculus (ICc) contains a representation of both the ipsilateral and contralateral auditory hemifields. The representation of ipsilateral space is found in the “core” of the ICc, a subdivision defined by the terminal field of nucleus laminaris, the avian analogue of the medial superior olivary nucleus. The representation of contralateral space is found in the lateral portion of the “shell” of the ICc. The shell surrounds the core and is defined by the terminal field of the nucleus angularis, one of the cochlear nuclei. The representation of ipsilateral space in the core of the ICc may be accounted for by the crossed projection from the nucleus laminaris because most of the nucleus laminaris is devoted to a representation of contralateral space.We present evidence to suggest that the representation of contralateral space is due to a commissural projection from the core of one side to the lateral shell of the opposite side. Injection of horseradish peroxidase (HRP) into the lateral portion of the ICc shell produced retrogradely labeled somata in the core of the opposite side. Injection of tritiated proline into the core produced anterograde label confined to the lateral shell, thus confirming the observations made with HRP. Thus, for example, the left ICc core, which contains predominantly a representation of the left hemifield, innervates the right lateral shell, endowing it with a representation of the left, or contralateral hemifield. The representation of contralateral space in the lateral shell is ultimately conveyed to the external nucleus of the inferior colliculus where it contributes the horizontal axis to a two‐dimensional map of space.
Ultrastructural analysis of axosomatic contacts on functionally identified primate spinothalamic tract neurons
Authors: Carlton S. M. , Lamotte C. C. , Honda C. N. , Surmeier D. J. , Delanerolle N. , Willis W. D. 
Published: January 2005

AbstractThe morphology and frequency of axosomatic contacts on three functionally identified primate spinothalamic tract (STT) cells were analyzed at the electron microscopic level. The STT cells analyzed were wide‐dynamic‐range neurons responsive to activation of low‐ and high‐threshold cutaneous afferents innervating the foot. The somas were located in the lateral border of lamina V; the dendritic trees were oriented dorsally and were very extensive. Numerous spinelike appendages were observed emanating from two of the cell bodies. Terminal types contacting the cell bodies were categorized at several different layers through each neuron. Six morphologically different terminal types were established following analysis of serial sections. Profiles classified as round (R) terminals containing round clear vesicles and zero or one densecore vesicle made up over 50% of the total population in contact with the STT somas. Profiles containing round clear vesicles and two to four small‐diameter dense‐core vesicles (D1 category) made up approximately 10% of the population in contact with each soma. Flat (F) terminals with oblong or flattened clear vesicles made up approximately 8% of the population. The remaining three categories (D2, L1, and L2) distinguished by the number and size of the dense‐core vesicles made up a small percentage of the total population in contact with the cell bodies. The distribution of terminal types on the soma proper versus somatic spines was also determined for one cell. The proportions of the six terminal types contacting the soma of these cells were very similar, although the physiological characteristics of each cell were different. However, the relative proportions of terminal types on these three lamina V STT cell bodies were different from those previously reported contacting somata in lamina V, suggesting that there may be a unique innervation of STT cells that differentiates them from other cell types in lamina V.
Connectional analysis of the ipsilateral and contralateral afferent neurons of the superior temporal region in the rhesus monkey
Authors: Cipolloni P. B. , Pandya D. N. 
Published: January 2005

AbstractThe interhemispheric and ipsilateral afferents of the superior temporal region (STR) were investigated with the aid of fluorescent retrograde tracers (Diamidino Yellow and Fast Blue). Different tracers were injected in selected cortical areas of the STR of each hemisphere of four rhesus monkeys. The results show that the interhemispheric afferents originate not only from the homotopic but also from heterotopic areas. The heterotopic areas giving rise to interhemispheric projections correspond to cortical areas of the origin of the ipsilateral projections. Although there is considerable overlap of labeled neurons of both afferent systems, only occasional double‐labeled neurons are found. Whereas the laminar patterns of ipsilateral neurons of origin vary considerably, the interhemispheric projection neurons are located mainly in cortical layer III.This study provides additional information about the ipsilateral connectional organization of the superior temporal region. That is, the primary auditory area receives projections not only from adjacent lateral and medial cortical regions but also from adjoining rostral and caudal cortical regions. Thus, the highly differentiated primary auditory cortical area receives strong projections from the surrounding less‐differentiated cortical regions. This connectional pattern is discussed from the perspective of the growth ring concept of cortical development.
Developing retinotectal projection in larval goldfish
Authors: Stuermer Claudia A. O. , Raymond Pamela A. 
Published: January 2005

AbstractThe retinotectal projection in larval goldfish was studied with the aid of anterograde filling of optic fibers with HRP applied to the retina. The results show that optic fibers have already reached the tectum and begun to form terminal arbors in newly hatched fish. The projection is topographic in that fibers from local regions of the retina project to discrete patches of tectum, with the smallest patch covering 3.5% of the total surface area of tectal neuropil. Many fibers in young larvae have numerous short side branches along their length and only some of them show evidence of terminal sprouting. The arbors are approximately elliptical in shape and average about 1,500 μ;m2. Growth cones are seen frequently. In older Iarvae, terminal arbors are larger and more highly branched, and they have begun to resemble those in adult fish. Fibers terminate in two strata; those in the upper layer are smaller (1,800 μ;m2 on average) than those in the deeper stratum (4,000 μ;m2 on average). The fraction of tectal surface area covered by individual arbors (the “tectal coverage”) ranges from 1.5% to 3% of the total surface area of the tectal neuropil. In contrast, the tectal coverage of individual arbors in young adult goldfish is much smaller, ranging from 0.02% to 0.42% of tectal surface area (Stuermer, '84, and unpublished). This apparent increase in precision of the map in older animals is not due to retraction of arbors, which are slightly larger in adults, but is accounted for by overall tectal growth: the tectal neuropil in goldfish increases in area by about 250‐fold during this period (Raymond, '86).
Structure‐function relationships in rat brainstem subnucleus interpolaris: IV. Projection neurons
Authors: Jacquin Mark F. , Barcia Michele , Rhoades Robert W. 
Published: January 2005

AbstractIn a companion paper (Jacquin et al., '89), the structure and function of local circuit (LC) neurons in spinal trigeminal (V) subnucleus interpolaris (Sp Vi) were described. The present report provides similar data for 44 projection neurons in Sp Vi. Of these, 25 thalamic, 16 cerebellar, 2 superior collicular, and 1 inferior olivary projecting neurons were studied. The majority responded to vibrissa(e) deflection, and all except 4 of these had multivibrissae receptive fields. The remainder were responsive to either guard hair deflection or indentation of glabrous skin. Latencies to V ganglion shocks were suggestive of monosynaptic activation from the periphery.SpVi projection neurons were topographically organized in a manner consistent with that of their primary afferent inputs. Nonvibrissa sensitive cells had diverse morphologies. Morphometric analyses of the more heavily sampled thalamic and cerebellar projecting, vibrissa(e)‐sensitive cells indicated the following. (1) As compared to LC neurons, projection neurons had bigger receptive fields, cell bodies, dendritic trees, and axons; less circular dendritic trees; a greater preponderance of spiny dendrites and fewer axon collaterals in Sp Vi. (2) Dendritic tree extent correlated significantly with receptive field size, thus suggesting that dendritic tree size is one mechanism contributing to receptive field size in vibrissae‐sensitive projection neurons. (3) V thalamic cells had significantly bigger receptive fields and dendritic trees, and also give off more local axon collaterals, than V cerebellar neurons. Collicular and inferior olivary projecting neurons shared structural and functional attributes with other Sp Vi long‐range projecting cells.Structure‐function relationships exist for vibrissa‐sensitive projection neurons in Sp Vi. The relevant parameters correlating with projection neuron morphology are receptive field size and projection status, whereas for Sp Vi LC neurons the relevant correlative parameter is peripheral receptor association.
Morphology of augmenting inspiratory neurons of the ventral respiratory group in the cat
Authors: Sasaki Hiroshi , Otake Kazuyoshi , Mannen Hajime , Ezure Kazuhisa , Manabe Motomu 
Published: January 2005

AbstractThe present study examined, in Nembutal‐anesthetized and artificially ventilated cats, the morphologic properties of the inspiratory neurons of the ventral respiratory group (VRG). Horseradish peroxidase (HRP) was injected into 21 augmenting inspiratory or late inspiratory neurons with peak firing rates in the late inspiratory phase. The majority of the stained neurons were antidromically activated by stimulation of the cervical cord. Thirteen somata, located within or around the nucleus ambiguus (AMB), between 100 μm caudally and 2,000 μm rostrally to the obex, were stained. In ten cases, the stem axons issuing from the cells of origin coursed medially to cross the midline without giving off any axonal collaterals. Three neurons gave rise to axonal collaterals on the ipsilateral side, distributing boutons in the medullary reticular formation, in the vicinity of the AMB, hypoglossal nucleus, solitary tract, and dorsal motor nucleus of the vagus. In eight neurons, only the axons were labeled; in four of these, which were antidromically activated from the spinal cord, the stem axons crossed the midline 2,000‐3,000 μm rostral to the obex and descended in the reticular formation around the AMB down to the cervical cord. They issued several axonal collaterals, distributing terminal boutons at the level of the caudal end of the retrofacial nucleus and about 1,000 μm rostral and caudal from the obex. Terminals were found mainly in and around the AMB, and a few were found in the vicinity of the dorsal motor nucleus of the vagus. The remaining four nonactivated axons distributed their terminal boutons widely in the reticular formation around the AMB. Thus, the augmenting inspiratory neurons of the VRG were shown to project not only to the spinal cord, but also to the VRG, hypoglossal nucleus, and dorsal motor nucleus of the vagus.
Afferent connections of the oculomotor nucleus in the chick
Authors: Labandeira‐garcia J. U. , Guerra‐seijas M. U. , Labandeira‐garcia J. U. , Jorge‐barreiro F. J. 
Published: January 2005

AbstractHorseradish peroxidase was injected into the oculomotor nucleus of the chick in order to locate and characterize the neurons projecting to this nucleus. In the rostral mesencephalon, 120‐180 neurons were labelled in the medial area of the ipsilateral nucleus campi Foreli; 190‐220 in the interstitial nucleus of Cajal (most of them contralateral); and smaller numbers bilaterally in the medial mesencephalic reticular formation, the nucleus of the basal optic root complex, and the central grey matter. More caudally, numerous neurons were labelled in the contralateral abducens nucleus and the vestibular complex and a few in the nucleus reticularis pontis caudalis. Labelled neurons appeared ipsilaterally in the caudal region of the nucleus vestibularis superior and in the rostral tip of the nucleus descendens just lateral to the tractus lamino‐olivaris. In the contralateral vestibular complex, a group of labelled cells observed in the dorsolateral area may be homologous to the mammalian cell group Y. At the level of the contralateral abducens nucleus, the most numerous group of cells (625‐700) projecting to the oculomotor nucleus formed a lateromedial fringe that affected the nucleus tangentialis, the rostral tip of the nucleus descendens and the ventrolateral region of the nucleus medialis. Only a few labelled neurons were seen in the contralateral nucleus vestibularis superior, the ipsilateral cell group A, and the ipsilateral nucleus vestibularis medialis.
Extracellular matrix components of the peripheral pathway of chick trigeminal axons
Authors: Moody Sally A. , Quigg Marks S. , Little Charles D. 
Published: January 2005

AbstractThe directed growth of axons to their peripheral targets during development may be influenced by a variety of intrinsic and environmental factors, the latter including the pattern of extracellular matrix components in the region through which they grow. We investigated the localization within the chick trigeminal mesenchyme of a variety of extracellular matrix molecules (laminin, heparan sulfate proteoglycan, entactin, collagen type IV) by using indirect immunofluorescence techniques. The trigeminal mesenchyme contained several of these molecules, but only laminin was specifically localized to trigeminal axon pathways. Double immunofluorescence localization of affinity‐purified laminin antibodies and monoclonal antibodies directed against a neuron‐specific β‐tubulin (to visualize growing axons and postmitotic V ganglion neurons) demonstrated that the V motor and sensory peripheral nerves confine their growth to two patches of laminin‐rich mesenchyme—a ganglionic laminin patch colocalized with V ganglion neurons and their axons, and a mandibular laminin patch colocalized with the V motor axons. Thus, laminin pathways in the mesenchyme may help guide V axons along their appropriate routes in the periphery. Double immunofluorescence localization of these laminin antibodies and monoclonal antibodies that recognize neural crest cells (to visualize precursors of V ganglion neurons and glia) demonstrated that the majority of cells within the ganglionic laminin patch were neural crest and differentiating neurons derived from the trigeminal epidermal placode. Since these cells often were laminin‐immunopositive, they might be a source of the ganglionic laminin matrix. The mandibular laminin patch contains nearly no neural crest cells, and probably contains the somitomeric precursors to the mandibular muscle mass. These results suggest that laminin, a matrix molecule implicated in the guidance of trigeminal peripheral axons, might be produced in localized patches by peripheral nervous system components and by muscle targets.
Identification and distribution of a proctolin‐like neuropeptide in the nervous system of the gypsy moth, Lymantria dispar, and in other lepidoptera
Authors: Davis Norman T. , Velleman S. G. , Kingan T. G. , Keshishian H. 
Published: January 2005

AbstractAlthough the neuropeptide proctolin has important functions in many arthropods, it is reported to be absent in Lepidoptera. Its possible occurrence in these insects was reinvestigated by bioassays of HPLC fractions and immunocytochemistry.A proctolin‐like substance was recovered from the frontal and subesophageal ganglia of Lymantria dispar. This substance has the same chromatographic retention time as proctolin; enzymatic degradation indicates that it is a peptide; it is bound by proctolin antisera; and thus it is indistinguishable from authentic proctolin.A small subpopulation of proctolin‐like immunoreactive (PLI) neurons was stained in the larval CNS of L. dispar, Manduca sexta, Trichoplusia ni, Galleria mellonella, and Vanessa cardui. Most prominent of these cells are median neurosecretory neurons in the brain, paired neurons in the frontal ganglion, two clusters of neurons in the subesophageal ganglion, paired lateral neurons in the thoracic ganglia, and dorsomedial neurons in the abdominal ganglia. Also, varicose PLI axons are found in the corpora cardiaca and perivisceral organs. In L. dispar, PLI cells also were found in the corpora cardiaca.The results of this study indicate that proctolin is of general occurrence in the Lepidoptera, that it has an important role in the stomatogastric nervous system, and that it may be released as a local neurohormone from various neurohemal organs.