bluuebunny/crossref_metadata_2025_split huggingface dataset:
Replacement of damaged cortical projections by homotypic transplants of entorhinal cortex
Authors: Gibbs Robert B. , Harris Eric W. , Cotman Carl W. 
Published: January 2005

AbstractThe extent to which transplants of embryonic cortical tissue can be used to replace damaged cortical projections has been examined. Embryonic entorhinal cortex was implanted into the entorhinal region of young adult rats that had previously received a lesion through the angular bundle. Projections between transplant and host were examined by using WGA‐HRP and the fluorescent dye Fast Blue. Implants selectively innervated areas of the host hippocampus and amygdala which normally receive entorhinal afferents. Implants were innervated by cells in the host diagonal band and, in one case, by cells in the contralateral entorhinal and/or presubicular cortex. In most cases, host fibers were differentially distributed within transplants, possibly reflecting an ability of host fibers to recognize and selectively innervate their appropriate targets even though the cellular organization of the implant is different from that present during normal development. These data suggest that homotypic implants of embryonic entorhinal cortex can, in some ways, replace severed cortical projections and may eventually be able to reconstituve normal cortical circuitry.
Central projections of cat retinal ganglion cells
Authors: Leventhal A. G. , Rodieck R. W. , Drehkr B. 
Published: January 2005

AbstractThe central projections of different groups of cat retinal ganglion cells were studied following small iontophoretic injections of horseradish peroxidase (HRP) into physiologically characterized sites. Analysis was restricted to labeled cells in the upper periphery of the nasal retina, contralateral to the injection site. Injections were made to the A lamina and C lamina of the dorsal lateral geniculate nucleus (LGNd‐A,C), the geniculate wing (LGNd‐W), the ventral lateral geniculate nucleus (LGNv), the pretectum (PT), and the superior colliculus (SC).The dendritic fields of alpha, beta, and epsilon cells were well labeled by the procedures we employed. A group, termed “g1,” had somal sizes within the range of the smaller beta and epsilon cells, but dendritic morphologies distinct from either class. The g1 group may consist of a number of types, but our material provided no basis for further distinguishing them. Many cells were observed that had smaller somas; all had thin axons, and few had dendritic fields that labeled to any significant extent. We were not able to further distinguish these cells, and refer to this group, which may include a number of types, as “g2” cells.From the peripheral nasal retina, alpha cells project to LGNd‐A, LGNd‐C, PT, and SC. Beta cells project to LGNd‐A, LGNd‐C, and PT. Epsilon and g1 cells project to the LGNd‐C, LGNd‐W, LGNv, PT, and SC.We determined the total spatial density of cells in the region of the retina analyzed, using a Nissl‐stained preparation. We then estimated the relative fraction of cells in each of the above groupings by injecting HRP throughout a cross section of the optic tract. Multiplying this relative fraction by the total spatial density gave an estimate of the spatial density of each of these groupings. From the spatial density of cells labeled from the injection site; we were able to estimate the fraction of cells of each retinal grouping that project to each of the zones investigated.By these calculations, almost all alpha cells from the upper nasal retina project to LGNd‐A and LGNd‐C; most project to SC, and about a third to PT. Beta cells, by contrast, project almost exclusively to LGNd‐A, with about 10% going to LGNd‐C, and about 1% to the PT. The great majority of epsilon cells, if not all, project to LGNd‐W, and up to half of this population also project to the other zones noted above. The remaining groups show little indication of branching, and separate to project, in varying proportions, to the terminal zones noted above.
Effects of continuous light on the retina of a fish, notemigonus crysoleucas
Authors: Penn John S. 
Published: January 2005

AbstractNotemigonus crysoleucas organisms were exposed to light at 1,250 and 850 lux in regimes of 12L:12D and 24L:0D. Each layer of cells in the retina was evaluated employing light microscopy and measurements for quantitative analysis were recorded from the retinas of over 150 fish. These values were compared for dorsal and ventral portions of the retina, for the two intensities, and for the two regimes. Fish maintained under the 24L:0D light regime exhibited significant light damage to the retina, characterized by reduction of outer segments of photoreceptors, reduction in the density of nuclear layers, and disintegration of ganglion cells. The dorsal portion of the retina experienced significantly greater deterioration than the ventral portion. Fish which had been subjected to 96 hours of continuous light displayed no ability to repair damage after 96 hours under 12L:12D.
Light microscopic observations on cat Renshaw cells after intracellular staining with horseradish peroxidase. I. The axonal systems
Authors: Lagerbäck Per‐Åke , Kellerth Jan‐Olof 
Published: January 2005

AbstractFive intracellularly HRP‐stained Renshaw cells were subjected to light microscopic analysis of the trajectories, branching patterns, and projections of the axonal systems.The cell bodies were located ventrally in lamina VII. In three neurons the axon originated from the cell body and in the remaining two cells from a dendrite. After a 600–870‐μm distance the axons entered the ventral funiculus, where all of them continued rostrally. Two axons also gave off a caudal branch in the funiculus. The diameters of the main axons varied between 2.1 and 10.0 μm.The main axons gave off one to four first‐order collaterals before entering the ventral funiculus and up to three collaterals could be seen to originate from the same node of Ranvier. In the ventral funiculus up to five first‐order collaterals could be traced from the same main axon. The axon collateral trees were often very extensive and daughter branches up to the 22nd order were observed. The distance between two successive branching points varied between 4 and 410 μm. A large number of boutonlike swellings were found along (59%) or at the ends of the collateral branches. At the most, 1,278 swellings originated from a single axon collateral tree. Most of the swellings were located in lamina IX, but they also appeared ventrally and dorsolaterally in lamina VII.
Light microscopic observations on cat Renshaw cells after intracellular staining with horseradish peroxidase. II. The cell bodies and dendrites
Authors: Lagerbäck Per‐Åke , Kellerth Jan‐Olof 
Published: January 2005

AbstractThe cell bodies and dendritic trees of five lumbosacral Renshaw cells of adult cats were studied in the light microscope (LM) after intracellular injection with horseradish peroxidase (HRP).The cell bodies were all located in the ventral part of lamina VII. The dendrites extended up to 0.7 mm from the cell body into the neighbouring parts of laminae VIII and IX as well as into more dorsal parts of lamina VII. The dendritic branching was sparse and about half the dendrites were unbranched. The mean diameter of the cell body was positively correlated to both the combined and mean diameters of the first‐order dendrites. Between four and eight dendrites originated from the cell bodies.The number of dendritic endbranches, the combined dendritic length, the mean dendritic length from the cell body to the termination of the end branches, the distance from the cell body to the termination of the most remote end‐branch, the dendritic surface area, and the dendritic volume all correlated positively with the diameter of the parent first‐order dendrite. The dendritic tapering was somewhat more pronounced in the Renshaw cells than previously observed in α‐ and γ‐motoneurons. The present data are discussed in relation to previous morphological observations on Renshaw cells and α‐ and γ‐motoneurons.
Colocalization of GAD‐like immunoreactivity and 3H‐GABA uptake in amacrine cells of rabbit retina
Authors: Mosinger Judith L. , Yazulla Stephen 
Published: January 2005

AbstractRabbit retinae were double labeled to determine the degree of colocalization of glutamic‐acid‐decarboxylase‐like immunoreactivity (GAD‐like IR) and 3H‐GABA uptake using light (LM) and electron microscopic (EM) auto‐radiography. Both GAD‐like IR and 3H‐GABA uptake were found in amacrine cell bodies in the inner nuclear layer (INL) as well as in cell bodies in the ganglion cell layer (GCL), and throughout the inner plexiform layer. GAD‐like IR was found in 32% of the amacrine cells in the INL, 86% of which also showed 3H‐GABA uptake; 3H‐GABA uptake was observed in 38% of the amacrine cells. However, only 72% of these cells showed GAD‐like IR. Labeled cells in the GCL were only 10–15% as common as similarly labeled cells in the INL. As in the INI., all GAD‐positive cells in the GCL were double labeled, but only 53% of the cells taking up 3H‐GABA were double labeled. We suggest that labeled cells in the GCL were ganglion cells rather than displaced amacrine cells. Cells, in both the INL and GCL, that showed 3H‐GABA uptake but no GAD‐like IR had a higher average grain density than double‐labeled cells, indicating that uptake by these cells was specific. The relevance to GABAergic function of 3H‐GABA uptake without an indication of GAD‐like IR is yet to be determined. Statistical analysis at the EM level showed that one‐third of the GAD‐positive synaptic terminals of amacrine cells were double labeled after a 4‐month exposure. Longer exposures at the EM level should reveal a higher percentage of GAD‐positive terminals because at the LM level, one‐half of the double‐labeled cell bodies were “lightly” labeled with grains. The high degree of colocalization of GAD‐like IR and 3H‐GABA uptake suggests that both markers may be useful for labeling GABAergic neurons in the rabbit retina.
Specific responsiveness of chick trigeminal motor nucleus explants to target‐conditioned media
Authors: Heaton Marieta B. , Wayne Denise B. 
Published: January 2005

AbstractExplants of the neural tube from stage 11 chick embryos containing the metencephalic trigeminal (V) motor nucleus were cultured in standard control medium, in medium conditioned by appropriate target musculature (the mandibular process of the first visceral arch that gives rise to jaw musculature innervated by motor V) or in medium conditioned by inappropriate target musculature (rostral limb bud tissue). The appropriate and inappropriate muscle tissues were of the same developmental stage (stage 22) and were in similar states of differentiation. At this point in vivo, both are just beginning to be innervated. The neuritic outgrowth from the explants was quantified after 6 days in vitro. While explants from all three groups appeared healthy and exhibited some neuritic outgrowth, the density and complexity of this growth was significantly greater in the group cultured with the appropriate (jaw) muscle‐conditioned medium. Growth in this group significantly surpassed that of both the control and the inappropriate (limb) muscle‐conditioned medium group. The inappropriate muscle‐conditioned medium group did not differ from the control group.These results demonstrate a specific responsiveness of the trigeminal motor nucleus population to its appropriate target tissue. Since relatively small amounts of the muscle‐conditioned medium were used with each explant, it is suggested that there is a high degree of sensitivity of this population to factors present in their target at the time innervation would normally be occurring. It is hypothesized that such selective responsiveness may play a role in guiding or sustaining growth during normal neurogenesis.
Projections of thalamic gustatory and lingual areas in the monkey, Macaca fascicularis
Authors: Pritchard T. C. , Hamilton R. B. , Morse J. R. , Norgren R. 
Published: January 2005

AbstractThe efferent projections of the parvicellular division of the ventroposteromedial nucleus of the thalamus (VMPpc; thalamic taste area) were traced to cortex in Macaca fascicularis by using tritiated amino acid autoradiography. Labeled fascicles could be traced from VPMpc to two discrete regions of cortex. The primary efferent projection was located on ipsilateral insular‐opercular cortex adjacent to the superior limiting sulcus and extended as far rostrally as the posterior lateral orbitofrontal cortex. An additional projection was located within primary somatosensory (SI) cortex subjacent to the anterior subcentral sulcus. Following autoradiographic injections in VPM, the trigeminal somatosensory relay, a dense terminal plexus was labeled on SI cortex of both pre‐ and postcentral gyri, but not within insular‐opercular cortex. The autoradiographic data were verified by injecting each cortical projection area with horseradish peroxidase (HRP) and observing the pattern of retrogradely labeled somata within the thalamus. Injections in the precentral gyrus near the anterior subcentral sulcus retrogradely labeled neurons within VPMpc, whereas injections further caudally near the floor of the central sulcus labeled, neurons within VPM. Injections of HRP within opercular, insular, or posterior lateral orbitofrontal cortex retrogradely labeled neurons within VPMpc.
Distribution and morphology of tegmental neurons receiving nigral inhibitory inputs in the cat: An intracellular HRP study
Authors: Noda T. , Oka H. 
Published: January 2005

AbstractIntracellular recordings and morphological identification of neurons by means of intracellular HRP staining were performed in the midbrain‐pontine tegmentum of the cat. Electrical stimulation of the substantia nigra, pars reticulata, induced short‐latency inhibitory postsynaptic potentials in tegmental neurons, as previously reported. These tegmental neurons were distributed not only in the pedunculopontine tegmental nucleus (PPTN) (26 cells), but also in the cuneiform nucleus (CNF) (13 cells), the central gray substance (CG) (four cells), the parabrachial nucleus (three cells), and the tegmentum between the inferior colliculus and the CG (two cells). The morphological characteristics of the HRP‐stained tegmental neurons were analyzed by camera lucida drawings of 16 well‐stained cells, i.e., ten PPTN neurons, three CNF neurons, two neurons in the tegmentum between the IC/CG, and one CG neuron. All of these neurons seem to be classified as “isodendritic” neurons. Regardless of the soma size (15–120 μm in diameter), most of the tegmental neurons showed wide dendritic fields of 1‐2 mm, mediolaterally, and 0.5–1. mm, dorsoventrally.These results indicate that the nigrotegmental projections exert an inhibitory influence on the neurons located in a wide variety of nuclei of the midbrain‐pontine dorsal tegmentum.
The early embryogenesis of papillary (sweat duct) ridges in primate glabrous skin: The dermatotopic map of cutaneous mechanoreceptors and dermatoglyphics
Authors: Dell David A. , Munger Bryce L. 
Published: January 2005

AbstractThe present study documents the early innervation of the epidermis prior to the onset of differentiation of the papillary (sweat duct) ridge in glabrous digital skin of rhesus monkey embryos measuring 45, 50 and 55 mm (crown‐rump) length. We observed small papillary ridges, spaced at a distance of approximately 40 μm, projecting into the dermis in the center of the distal glabrous digital pad of digits 2–5 in the 55‐mm embryo. The other digital pads lacked any sign of ridge formation. A two‐dimensional, approximately hexagonal grid of afferent nerves was present in the superficial dermis of all digital and palmar pads. At regular intervals of approximately 40 μm, afferent nerves ascended from the superficial dermal nerve plexus and innervated the overlying epidermis. By electrom microscopy, axonal growth cones were identified contacting Merkel cells that projected several microns down into the superficial dermis in the digital pad of digit 3. Thus, the earliest wave of differentiated dorsal root ganglion neuroblasts innervates Merkel cells. Schwann cells partially encircled these growing axon tips and could be identified by the presence of rough endoplasmic reticulum and free ribosomes. The youngest embryo studied had no sign of ridge formation; however, axons ascended from the superficial dermal nerve net at 30–40‐μm intervals to innervate the epidermis. We conclude that afferent nerve fibers provide a two‐dimensional grid that could modulate the spacing and arrangement of the papillary or sweat duct ridges of successive digits. Such an interaction is possible between digits based on the overlapping dermatotopic maps of each rete ridge. An abnormal fingerprint could thus reflect abnormal dorsal root ganglion neuroblasts expressed through mesenchyme and epidermis.
Optic tectum, of the eastern garter snake, thamnophis sirtalis. I. Efferent pathways
Authors: Dacey Dennis M. , Ulinski Philip S. 
Published: January 2005

AbstractExtracellular, iontophoretic injections of horseradish peroxidase were used to anterogradely fill axons efferent from the optic tectum in garter snakes. The tectal efferent pathways consist of six axon types with distinct projections and terminal morphologies. Tectogeniculate axons pass into the diencephalon via the optic tract, bearing collaterals that form spatially restricted, rodlike arbors in the pretectum, the ventral lateral geniculate nucleus, and the ventrolateral nucleus. Tectoisthmi axons exit the tectum as a thin‐caliber component of the ventral tectobulbar tract. They form spatially restricted, spherical arbors within nucleus isthmi. Tectoisthmobulbar axons also give rise to small, spherical arbors within nucleus isthmi, but the parent axons continue caudally into the pontine and medullary reticular formation issuing many short collateral branches. Tectorotundal axons reach the diencephalon via the tectothalamic tract and give rise to fine terminal collaterals in the nucleus of the tectothalamic tract ipsilaterally and in nucleus rotundus bilaterally. Single axons form sheetlike terminal fields that span the rostrocaudal extent of nucleus rotundus. Ipsilateral tectobulbar axons descend into the midbrain tegmentum where they issue several thick collaterals that terminate widely throughout the nucleus lateralis profundus mesencephali. The parent axon continues caudally giving off several widely spreading collaterals within the pontine and medullary reticular formation. Crossed tectobulbar axons enter the dorsal tectobulbar tract and cross the midline to form the predorsal bundle. Single axons give rise to terminal collaterals in the nucleus lateralis profundus mesencephali bilaterally, the contralateral pontine and medullary reticular formation, and the intermediate gray of the cervical spinal cord.
Monoclonal antibodies to the cockroach nervous system
Authors: Denburg Jeffrey L. , Caldwell Robert T. , Marner Joyce A. M. 
Published: January 2005

AbstractIn the cockroach nervous system individual motor neurons may be identified with respect to their position. in the thoracic ganglia and to the muscles they innervate. When their axons are cut they have the ability to regrow such that when regeneration is completed they have specifically reinnervated their normal target muscles. This suggests the existence of a specific intercellular recognition process between motor neurons and muscles, and that neurons innervating different muscles are biochemically distinct from one another. The goal of this study was to use hybridoma techniques to obtain monoclonal antibodies that bind to some motor neurons and not others.Mice were injected with whole nerve cord and hybridoma supernatants were screened immunohistochemically on sections of ganglion and leg muscle. The monoclonal antibodies were categorized according to four types of specificity: tissue, regional, cell‐type, and neuron‐subset specificities. Antibodies expressing neuron‐subset specificity were obtained very rarely. The probability of their occurrence could be increased by treating the mice with immunosuppressant drugs after initial administration of immunogen or by fixing the immunogen with paraformaldehyde in a manner similar to that of the tissue sections used in the screening process.Two of the neuron‐subset specific monoclonal antibodies (MAbs) are of particular interest with respect to the goals of this study. They bind to axon terminals in the muscles of some neurons and not others. They do not bind to neuronal cell bodies in the ganglion, which makes identification of the neurons difficult. However, from the known innervation pattern of the coxal depressor muscles it appears that one of these MAbs selectively binds to axon terminals from either the inhibitory motor neurons or the dorsal unpaired median cells. Other antibodies of interest bind selectively to the synapse‐rich neuropile in the ganglia or to peripheral parts of the nervous system like the nerve roots.
Optic tectum of the eastern garter snake, Thamnophis sirtalis. III. Morphology of intrinsic neurons
Authors: Dacey Dennis M. , Ulinski Philip S. 
Published: January 2005

AbstractExtracellular iontophoretic injections of horseradish peroxidase and Golgi preparations were used to study the distribution and morphology of intrinsic neurons of the garter snake optic tectum. Four morphologically distinct classes of neurons were identified. The type A neuron is found throughout the retinorecipient tectal layers. It has a large, fusiform soma and infrequently branching dendrites than radiate in the horizontal plane and are studded with varicose appendages. An axon arises from the soma or proximal dendrite and gives rise to, widely spreading branches that overlap the cell's dendritic field. The type B neuron has a small, spherical soma in sublayer b of the stratum fibrosum et griseum superficiale. Thick, varicose dendrites ascend from the soma and form a bushy arbor in the overlying sublayer a. A thin axon descends vertically from the soma and arborizes in vertical alignment with the cell's dendritic field in sublayer c of the stratum fibrosum et griseum superficiale and the upper third of the stratum griseum centrale. The type C neuron is a bipolar cell with a small, vertically fusiform soma situated at the upper border of the stratum griseum centrale. Thin, sparsely branching dendrites extend vertically into the superficial and central gray layers. An axon arises from the soma and courses ventrally into the stratum griseum centrale where it gives rise to a plexus of widely spreading branches that extend medially from the cell's dendritic field. The type D neuron is a small, stellate cell with a spherical soma and fine, appendage‐laden dendrites that are restricted to the stratum griseum centrale. The axon of the type D cell courses in the central gray, where it gives rise to widely spreading branches that extend laterally from the cell's dendritic field.