bluuebunny/crossref_metadata_2025_split huggingface dataset:
Organization and efferent connections of transplanted suprachiasmatic nuclei
Authors: Wiegand Stanley J. , Gash Don M. 
Published: January 2005

AbstractThe hypothalamic suprachiasmatic nucleus (SCh) is the principal brain structure involved in the generation of circadian rhythms. In the present study, we have employed immunohistochemical techniques to evaluate the development of the fetal SCh following its transplantation to the brain of adult host animals. Donor hypothalami were obtained from normal Long‐Evans fetuses and transplanted to the lateral, third, or fourth ventricle of Brattleboro rats, Neuronal aggregations exhibiting the organotypic features of the SCh were present in over 90% of the grafts recovered at each transplantation site. Like the normal endogenous SCh, SCh‐like cell groups identified within the transplants contained a prominent population of parvicellular (9–13 μm), neurophysin‐containing neurons that were immunopositive for vasopressin (VP) but not oxytocin. These SCh‐like cell groups also invariably contained similar small neurons that were immunoreactive for vasoactive intestinal polypeptide (VIP). Typically, VP and VIP immunoreactive perikarya were concentrated in contiguous, complementary parts of the grafted SCh, but fibers immunoreactive for either peptide were distributed throughout the extent of the nucleus.Because the brain of the Brattleboro rat is deficient in vasopressin, it was possible to evaluate the projection of the vasopressinergic component of the transplanted SCh to the host brain. Although SCh were identified in grafts recovered from each intraventricular transplantation site, an appreciable input to the host brain could be identified only when the fetal tissue was grafted to the third ventricle. Here, grafted SCh established efferent connections with periventricular diencephalic structures which ordinarily receive a projection from the in situ SCh. Specifically, VP immunoreactive fibers originating from transplanted SCh were identified in the medial preoptic area, the periventricular and dorsomedial hypothalamic nuclei, the paraventricular nuclei of the thalamus and hypothalamus, and in the retrochiasmatic area, arcuate nucleus, and suprachiasmatic nucleus of the host brain. These results demonstrate that the fetal SCh not only survives transplantation but also retains its distinguishing cytological features and the capacity to form an appropriately restricted set of efferent connections with the brain of adult host animals.
Anatomical connections of the prepositus and abducens nuclei in the squirrel monkey
Authors: Belknap Dianne B. , McCrea Robert A. 
Published: January 2005

AbstractThe primary goal of this investigation was to identify the areas of the brainstem and cerebellum that provide afferent projections to the nucleus prepositus hypoglossi in primates. After horseradish peroxidase conjugated to wheat germ agglutinin (WGA‐HRP) was injected into the prepositus in squirrel monkeys (Saimiri sciureus), the largest populations of retrogradely labeled neurons were found in the vestibular nuclei, the contralateral perihypoglossal nuclei, and the medullary and pontine reticular formation. Unlike the cat, the prepositus in Saimiri received substantial projections from the nucleus raphe dorsalis and the central mesencephalic reticular formation, whereas few or no labeled cells were found in the cerebellar cortex, the superior colliculus, or the nucleus reticularis tegmenti pontis. By comparing the afferents to the prepositus with those to the abducens nucleus, we found that all regions projecting to the abducens also projected to the prepositus, without exception. Anterogradely transported WGA‐HRP showed that the major brainstem recipients of prepositus efferents were the vestibular and perihypoglossal nuclei, the inferior olive, the medullary reticular formation, and the extraocular motor nuclei. In the cerebellar cortex, the prepositus projected to restricted regions of crura I and II as well as the caudal vermis and vestibulocerebellum. The many parts of the oculomotor system receiving input from the prepositus and the parallel innervation of the prepositus and the abducens by a large number of premotor centers lend support to the hypothesis that the prepositus may distribute an efference copy of motor activity, and may also play an important role in the process of neural integration.
Taurine‐like immunoreactivity in the brain of the honeybee
Authors: Schäfer Sabine , Bicker Gerd , Ottersen Ole P. , Storm‐Mathisen Jon 
Published: January 2005

AbstractTaurine (2‐aminoethanesulfonic acid) is one of the most abundant free amino acids in the insect central nervous system. We have investigated the distribution of taurine‐like immunoreactivity in the brain of the honeybee with an antiserum recognizing fixed taurine. Taurine‐like immunoreactivity appeared within neuronal perikarya, neurites, and terminals, whereas glial cells were unlabelled. All photoreceptor cells of the compound eyes and the ocelli were stained. So were the fibers of the anterior superior optic tract, which connects the optic lobes to the mushroom bodies in the median protocerebrum. In the mushroom bodies the majority of intrinsic Kenyon cells showed high levels of taurine‐like immunoreactivity. The lateral antennoglomerular tract, which interconnects the mushroom bodies with the antennal lobes, was also intensely stained. In. the antennal lobes, strong labelling was observed within, a few fibers that invade a set of posterior glomeruli from the posterior margin. Sensory projections from the antennal nerve into the antennal lobes showed only intermediate levels of staining. Sensory projections into the dorsal lobe were devoid of taurine‐like immunoreactivity. Labral, mandibular, maxillary, and labial nerves, which innervate the various parts of the feeding apparatus, contain a set of five to eight heavily stained fibers. A comparison of taurine‐like immunoreactivity with glutamate‐ and GABA‐like immunoreactivities in the brain of the honeybee indicates that the three amino acids are enriched in distinct neuronal populations.
Remodeling of nerves during claw reversal in adult snapping shrimps
Authors: Govind C. K. , Pearce Joanne 
Published: January 2005

AbstractAdult snapping shrimps, Alpheus heterochelis, undergo a reversal of their claw laterality following removal of the major claw, a process in which the existing minor claw transforms into a major and a new minor regenerates at the old major site. During such reversals the nerves to the ganglion are remodeled from one claw type to the other. Conversion of the nerves from the minor to the major type occurs within several days after removal of the contralateral major claw and involves the rapid addition of large numbers of sensory axons together with deletion of a few. Thus modeling of the nerves is essentially complete within the first intermolt in tandem with changes in the motoneurons but well ahead of changes in the muscle and external morphology. Conversion of the major nerves to the minor type is via massive degeneration of sensory axons during the first and second intermolts because of the loss of their peripherally located cell bodies. This is followed by proliferation of largely unmyelinated axons in the third intermolt, some of which become myelinated in the subsequent intermolts. Thus remodeling of the major nerves to minor, which is associated with the loss of a claw and the regeneration of a new minor claw, is a more traumatic and prolonged process compared to the remodeling of the minor nerves to major which is associated with the transformation of an existing claw.
Comparison of growth and reinnervation properties of cholinergic neurons from different brain regions grafted to the hippocampus
Authors: Nilsson Ola G. , Clarke Deborah J. , Brundin Patrik , Björklund Anders 
Published: January 2005

AbstractGrafts of five different types of central cholinergic neurons, from the septal‐diagonal band region, the nucleus basalis magnocellularis region (NBM), the striatum, the pontomesencephalic tegmentum of the brainstem, and the spinal cord, were compared with respect to their ability to grow and to reinnervate the cholinergically denervated hippocampal formation of adult rats. The areas were dissected from 14 to 15–day‐old rat fetuses, and the same number of viable cells (35 × 104) from each of the different regions were stereotaxically injected as cell suspensions into the hippocampus of rats subjected to a transection of the intrinsic septo‐hippocampal cholinergic pathways. At 17–19 weeks after transplantation, the various graft types differed considerably in their volume, the total amount of acetylcholinesterase (AChE)‐positive fiber outgrowth, and the innervation pattern and morphology of the AChE‐positive fibers growing into the host hippocampus. On average the NBM and spinal cord grafts had grown to become three to four times larger than the septal and the brainstem grafts, and 15–20 times larger than the striatal grafts. By contrast, the total ingrowth score of AChE‐positive fibers in the host hippocampus from the septal grafts was about twice that of the NBM and brainstem grafts, about five times greater than the striatal grafts, and about six times greater than that of the spinal cord grafts. The large NBM grafts thus exhibited similar fiber outgrowth to the much smaller brainstem grafts, and the AChE‐positive neurons of the grafted spinal cord grew very poorly into the hippocampus despite the fact that they survived very well. The innervation pattern and morphological features of the ingrowing AChE‐positive fibers in the host hippocampus proper and in the dentate gyrus resembled those of normal rats in animals with grafts from any of the three forebrain regions (i.e., septum, NBM, or striatum), whereas ingrowth from the brainstem and spinal cord grafts were markedly abnormal with respect to both innervation pattern and fiber morphology.These results provide further evidence that the overall survival, growth, and fiber outgrowth of intracerebral neural grafts depend on interactions with the surrounding host tissue. Since the ability to reinnervate the previously denervated host target was greatest for the neuron type normally innervating that area, i.e., the septal‐diagonal band neurons, we conclude that neuronal properties beyond the transmitter type are essential for the optimal performance of implanted neurons in intracerebral grafting experiments.
Response of endogenous glial cells to motor neuron degeneration induced by toxic ricin
Authors: Streit Wolfgang J. , Kreutzberg Georg W. 
Published: January 2005

AbstractThe injection of toxic lectin from Ricinus communis into the rat facial nerve resulted in suicide transport and rapid degeneration of facial motor neurons. The reaction of glial cells to neuronal death in comparison with nerve crush lesions was studied by using lectin‐HRP conjugates derived from Griffonia simplicifolia for the selective staining of microglial cells at both light and electron microscopic levels. In addition, the proliferative activity of microglia was assessed by quantification of 3H‐thymidine incorporation. The astrocytic response was evaluated by light microscopic immunocytochemistry for glial fibrilliary acidic protein.In the degenerating facial nucleus local microglial cells responded by rapid proliferation and phagocytosis of neuronal debris. After nerve crush, no phagocytes were observed, but microglial proliferation and perineuronal satellitosis were prominent. The astrocytic expression of glial fibrillary acidic protein in response to nerve crush proceeded gradually over a period of several weeks after which it declined, contrasting with accelerated astrocytic hypertrophy and permanent glial scarring after neuronal degeneration.These results show that the expression of glial fibrillary acidic protein by fibrous astrocytes is intensified after lethal neuronal injury compared to sublethal insults. In the absence of any observations indicating participation of hematogenous elements, it is proposed that local microglial cells transform into brain macrophages.
Structure and distribution of dorsal unpaired median (DUM) neurones in the abdominal nerve cord of male and female locusts
Authors: Pflüger H.‐J. , Watson A. H. D. 
Published: January 2005

AbstractDorsal unpaired median (DUM) neurones in insects have been shown to modulate the activity of both skeletal and visceral muscle. It has been suggested that as a population they carry out a role analogous to that of the sympathetic nervous system in vertebrates; however, the extent of their distribution throughout the ventral nerve cord has not been assessed. This paper aims to fill this gap by systematically describing the number and morphology of DUM neurones in each of the abdominal ganglia of male and female locusts. To achieve this, the lateral nerves of each abdominal ganglion were backfilled to reveal the position of the somata of DUM neurones. To confirm their identity and reveal their structure, DUM somata were then impaled with microelectrodes and, after physiological characterization, the neurones were stained by intracellular injection with cobalt ions. In each of the first six abdominal ganglia of both sexes, two DUM neurones, one with axons in the tergal nerve and one with axons in the sternal nerve, were found. In the seventh abdominal, and the terminal, ganglion (composed of the eighth to eleventh neuromeres), there was considerable sexual dimorphism in DUM neurone distribution, which was most marked in those associated with some of the nerves innervating the genitalia. In the male, four clusters of somata in the seventh, eighth, and tenth segments have axons in the genital nerve. In the female, which lacks a genital nerve, clusters of DUM neurones, absent in the male, have axons in the seventh and eighth sternal nerves and the cercal nerve.
Serotonin‐containing neurons in Drosophila melanogaster: Development and distribution
Authors: Vallés Ana María , White Kalpana 
Published: January 2005

AbstractAntibodies made against serotonin (5HT) were used to identify the serotonin neuronal system in the developing and adult nervous system of Drosophila melanogaster. The 5HT neuronal pattern is composed of a small number of neurons, 84 in larvae and 106 in adults, distributed in clusters composed of one to five neurons in the CNS; 5HT immunoreactive (5HT‐IR) neurons appear to be predominantly intrasegmental interneurons; however, intersegmental 5HT‐IR fibers are observed and at least some neurons send peripheral fibers. Acquisition of 5HT immunoreactivity in the CNS occurs late in embryogenesis, by 16–18 hours, and most if not all the 5HT neurons appear to persist into adulthood. During early metamorphosis, the intensity of 5HT‐IR neuropil transiently decreases. Other changes in the CNS during this period are reflected in the appearance of two new 5HT clusters and 5HT‐IR neuropil in the developing optic lobes. Comparison of the 5HT‐IR pattern with other transmitter systems in Drosophila as well as comparison of the 5HT‐IR pattern within different insect species is presented.
Connections of the corpus cerebelli in the thornback guitarfish, Platyrhinoidis triseriata (Elasmobranchii): A study with WGA‐HRP and extracellular granule cell recording
Authors: Fiebig Eberhard 
Published: January 2005

AbstractThe neuronal connections of the cerebellar corpus in the guitarfish Platyrhinoidis triseriata were investigated by WGA‐HRP injections and extracellular recording of sensory evoked electrical activity. Injections of WGA‐HRP into the corpus resulted in retrograde labeling of the following cell groups bilaterally: pretectal and accessory optic nuclei, interstitial nucleus of Cajal, nucleus ruber, oculomotor and possibly trochlear nucleus, central (periaqueductal) gray, nucleus H, reticular formation of the midbrain, cerebellar nucleus, caudal part of nucleus R tentatively locus coeruleus and subcoeruleus field, octaval and trigeminal nuclei, intermediate octavolateralis nucleus, medial inferior reticular formation, lateral reticular nucleus, and spinal cord. Unilaterally labeled cells were seen in the contralateral inferior olive, which was found to project in. sagittal zones onto the molecular layer of the corpus. Terminal fields of efferent Purkinje cell axons were labeled over the ipsilateral cerebellar nucleus exclusively. Purkinje cells in different parts of the corpus project topographically onto subdivisions of the nucleus.Mapping of evoked electrical multiple unit activity recorded from the granule cell layer of the corpus shows separate visual and tactile areas, mostly confined to the anterior and posterior lobes, respectively. Granule cells within the tactile area also responded to lateral line stimuli and, at two distinct medial locations in the caudal and rostral parts of the posterior lobe, to weak electric field stimulation in the bath. The body surface is somatotopically represented in the tactile area, but discontinuities in the map might indicate that the somatotopy is “fractured.”
Distributions of tyrosine hydroxylase‐, dopamine‐β‐hydroxylase‐, and phenylethanolamine‐N‐methyltransferase‐immunoreactive neurons in the brain of the hamster (Mesocricetus auratus)
Authors: Vincent Steven R. 
Published: January 2005

AbstractAntibodies to the catecholamine synthetic enzymes tyrosine hydroxylase (TH), dopamine‐β‐hydroxylase (DBH), and phenylethanolamine‐N‐methyltransferase (PNMT) were used in an immunohistochemical analysis of the brain of the golden hamster. The distributions and morphological characteristics of neurons displaying immunoreactivity to these enzymes were examined in sets of adjacent sections. Various novel groups of TH‐immunoreactive neurons were found. A distinct feature observed in the hamster brain was the presence of a population of magnocellular multipolar neurons in the basal forebrain which displayed intense TH immunoreactivity. These cells were found predominantly in the vertical and horizontal limbs of the nucleus of the diagonal band of Broca and in the lateral preoptic area. Many small TH‐positive cells were also found scattered in the deeper layers of the cortex in the hamster. The pericentral divisions of the inferior colliculus contained a large number of TH‐immunoreactive neurons, and a few small bipolar cells in the lateral superior olive were also stained; A major cell group was found in the lateral parabrachial nucleus at the level of the locus ceruleus that displayed TH but not DBH immunoreactivity and was obviously separate from the TH‐ and DBH‐positive cells of the locus ceruleus. Additional TH‐positive cell groups were found along the seventh nerve, within the medial longitudinal fasiculus, in the nucleus raphe pallidus, and in the pars caudalis of the spinal trigeminal nucleus.The various catecholamine cell groups described by many people in the rat by use of histochemical and immunohistochemical techniques were also present in the hamster brain. These included the noradrenergic, TH‐ and DBH‐immunoreactive cell groups of the pons and medulla. The hamster also displayed groups of medullary neurons displaying immunoreactivity to TH, DBH, and PNMT. These appeared similar in distribution and morphology to the adrenaline cell groups described in the rat. TH‐immunoreactive cell groups in the olfactory bulb, hypothalamus, substantia nigra, and ventral tegmental area of the hamster appeared to correspond to the dopaminergic cells groups described in the rat and other species. In addition, as in the rat and cat, numerous TH‐positive cells were found in the dorsal motor nucleus of the vagus, the nucleus of the solitary tract, and the area postrema.These observations suggest that catechols may be present in neurons in the cortex, basal forebrain, auditory brainstem, and the parabrachial nucleus of the hamster. These studies also emphasize the need for caution in making‐ generalizations regarding transmitter distributions across species.
Distribution of catecholamine fibers in the cochlear nucleus of horseshoe bats and mustache bats
Authors: Kössl M. , Vater M. , Schweizer H. 
Published: January 2005

AbstractThe glyoxylic‐acid‐induced fluorescence technique was applied to demonstrate patterns of catecholaminergic innervation within the auditory brainstem of echolocating bats and the house mouse. In the cochlear nucleus of the rufous horseshoe bat (Rhinolophus rouxi) and the mustache bat (Pteronotus parnelli), species‐specific catecholaminergic innervation patterns are found that contrast with the relatively homogeneous innervation in the rodent.In both bats the subnuclei of the cochlear nucleus receive a differentially dense supply of catecholaminergic fibers, and within the subnuclei, the catecholamine innervation densities can be correlated with the tonotopic frequency representation. The areas devoted to the high‐frequency echolocation calls are less densely innervated than those regions which are responsive to lower frequencies.Apart from this common scheme, there are noteworthy distinctions between the two bats which correlate with specialized cytoarchitectural features of the cochlear nucleus. The marginal cell group, located medially to the anteroventral cochlear nucleus of Pteronotus, receives the densest supply of catecholaminergic fibers of all auditory nuclei. This plexus is formed by a morphologically distinct population of catecholaminergic fibers.
Cotransplantation of embryonic mouse retina with tectum, diencephalon, or cortex to neonatal rat cortex
Authors: Sefton Ann Jervie , Lund Raymond D. 
Published: January 2005

AbstractRetinae from embryonic mice were transplanted to the occipital cortex of neonatal rats together with their normal target regions, tectum or diencephalon, from embryonic mice or rats. In control experiments, retinae were cotransplanted with embryonic rat occipital cortex. In over 80% of the experimental animals, both transplants differentiated and grew. Ganglion cells in the retinae cotransplanted close to tectum or diencephalon survived for at least 15 weeks. Their survival was associated with the development of a distinct optic fiber layer and outgrowth of axons from the transplanted mouse retina. Specific innervation of distinct patches within the cotransplanted rat tectum or diencephalon was demonstrated by the use of an anti‐mouse antibody. The innervated regions, which could be as far away as 1.3 mm from the retinae, were correlated with cytological features of the Co‐transplanted tectum or diencephalon. By contrast, the host cortex was never innervated by the transplanted retinae. In the control animals in which the retinae were cotransplanted with occipital cortex and in four animals in which the cotransplants lay more than 2.7 mm apart, no ganglion cells were identified and there was no evidence of an optic fiber layer, outgrowth of axons, or innervation. These results support the idea that in order to survive, retinal ganglion cells need to innervate an appropriate target region. Further, the specific innervation of regions within the cotransplanted tectum or diencephalon suggests that these target regions are able to exert a tropic influence on the axons of retinal ganglion cells, even in the absence of many of the normal structure cues.