bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comparative study of the immunohistochemical localization of basic protein to myelin and oligodendrocytes in rat and chicken brain
Authors: Hartman Boyd K. , Agrawal Harish C. , Kalmbach Sandra , Shearer William T. 
Published: December 2004

AbstractAntisera to highly purified basic protein (BP)7 from rat and chicken brain were prepared and their purity and specificity demonstrated by double immunodiffusion and cross‐immunoadsorption. These antisera were used for immunohistochemical localization of BP in the brains of adult and developing rat and chick.Myelin basic protein was exclusively localized to myelin or the myelin forming elements of the CNS. It was present in high concentrations in white matter and absent in areas free of myelin. Neuronal parikarya and dendrites were negative as were axons cut in cross section and at Nodes of Ranvier. The latter was best observed in cross sections of human spinal cord demonstrating also the immunoreactivity of the antibodies with human BP. The internodal distance in a fine (1.5 μm) rat cortical fiber was determined to be approximately 45 μm. Myelin basic protein was shown to extend into cranial roots, in contrast to myelin proteolipid protein which abruptly lost fluorescence as the nerves emerged from the brain.During development, BP was first observed on the fourteenth day of incubation in chick and at birth in the rat. The protein appeared in oligodendrocyted and in association with fibers near these cells. Fluorescent processes were frequently observed connecting the oligodendrocytes with the fibers. As myelination progressed, the intensity of the immunohistochemical reaction decreased in the oligodendrocytes while the brightness in fibers increase. Eventually, the oligodendrocytes became undetectable. Fibers with immature myelin exhibited a beaded or varicosed appearance with the highest concentration of immunofluorescence in the outer portion of the varicosities. The varicosities were postulated to represent dilations in the newly forming sheath between intervals of compaction along the axon undergoing myelination. These dilations might represent areas of increased cytoplasmic volume which could serve as channels for transport and/or storage sites for myelin proteins prior to incorporation into the membrane. The varicosities became less prominent with the thickening of the myelin sheath and mature myelinated fibers became smooth. The process of synthesis of BP, transport of the protein to the varicosed fibers, and maturation of the myelin sheath was seen to progress in a more or less caudal to rostral direction as myelination of the CNS takes place. In the rat, this was accomplished over approximately a 30‐day period starting near the time of birth. In the chick, most of the myelination was accomplished in the three or four days immediately before hatching. At this time, innumerable oligodendrocytes were observed producing BP simultaneously in the major white fiber tracts. It is postulated that in chick some degree of oligodendrocytic cell death occurs normally during myelination.
Retinal projections in the tasmanian devil, Sarcophilus harrisii
Authors: Sanderson K. J. , Pearson L. J. , Haight J. R. 
Published: December 2004

AbstractRetinal projections were mapped in Tasmanian devils which had one eye injected with 3H‐proline. The retinal fibers terminate in seven regions in the brain. These are (1) dorsal lateral geniculate nucleus (LGNd), (2) ventral lateral geniculate nucleus, (3) lateral posterior nucleus, (4) pretectum, (5) superior colliculus, (6) hypothalamus and (7) accessory optic system. The pattern of retinal input to six of these regions is similar to that seen in other marsupials.The pattern of retinal projections to the LGNd, while basically similar to that observed in other polyprotodont marsupials, is much simpler than that seen in the related native cat, Dasyurus viverrinus. The LGNd of Sarcophilus presents the simplest cytoarchitectural organisation of any marsupial examined so far. Each LGNd receives overlapping projections from both eyes. Suggestions of an intermittent lamination are seen in the LGNd contralateral to an eye injection of 3H‐proline. On the ipsilateral side there are two patches of label, a large lateral patch and a smaller medial patch, both of which occupy areas receiving contralateral input. The monocular segment, occupying the ventral 40%; of the nucleus, is more extensive than has been reported in any other polyprotodont marsupial.
A topographic map of sensory cell terminal arborizations in the cricket CNS: Correlation with birthday and position in a sensory array
Authors: Murphey R. K. , Jacklet Alice , Schuster Lesley 
Published: December 2004

AbstractThe development of a group of club‐shaped sensilla called clavate hairs, located on the cerci of the cricket (Acheta domesticus), was examined morphologically. The clavate hairs are located on the base of the cercus and are thought to inform the animal of its orientation with respect to gravity. There are two groups of clavate hairs distinguished from one another by the orientation of their sockets: a dorso‐medial group whose sockets are oriented perpendicular to the long axis of the cercus and a ventro‐medial group inclined 45–60° away from the perpendicular. The ventro‐medial group consists of a series of rows of sensilla running parallel to the long axis of the cercus.By examining a cast‐off exoskeleton in the scanning electron microscope and comparing it with newly developed cuticle of the subsequent instar (Fig. 3), we showed how receptors were added to the ventro‐medial array of clavate hairs. The first ventral hair (#10, Fig.1) appeared in the second instar. Three more hairs were added in the third instar: two (#11 and #12) proximal to hair 10 forming the first row and one (#20) medial to 11 and initiating the second row. After the third instar one hair was usually added proximal to each row each time the specimen molted. Because of the regular positioning of hairs and their orderly addition to the array, it is possible to identify uniquely all of the hairs in the three largest rows of ventral hairs (Fig. 4).We developed a simple method for staining the neuron associated with each hair. A hair was injured by cutting off its tip. A bubble of cobaltous acetate was then placed on the hair for 18–20 hours and only the neuron associated with the injured hair took up the stain.The synaptic terminal arborizations of identified neurons examined in this manner were unique and reproducible from specimen to specimen (Fig. 6). Furthermore, there is a topographic order to the terminal arborizations. Within one row the oldest neurons project furthest into the nervous system and arborize over the greatest area, whereas younger neurons arborize in more restricted areas near the entrance of the cercal nerve. Thus it was concluded that birthday was corretated with the morphology of the synaptic arborization.By staining neurons that were the same age but located in different rows, we determined that birthday was not the only variable influencing the morphology of the terminal arbors. The terminal arbors of neurons 11 and 20, both of which first appear in the third instar, were very different from one another. Thus another variable, presumably position on the body surface, was also correlated with the morphology of a neuron's terminal arborization. We concluded from these results that position on the cercus as well as birthday is encoded in the developmental program of these neurons and that the morphology of their terminal arborizations is a joint function of these two variables.
Differences between the peripheral and the central nervous system in permeability to sodium fluorescein
Authors: Malmgren Leslie T. , Olsson Yngve 
Published: December 2004

AbstractSodium fluorescein (SF) was used as a very small tracer (mol wt 376; 5 A° diameter) to examine diffusion barriers in peripheral nerves and to compare them to those in other regions of the nervous system. The technique involved immobilization of the tracer by rapid freezing, followed by freezedrying and vacuum embedding in paraffin. The localization of the SF was then determined in tissue sections using fluorescence microscopy.Even at the highest doses of intravenously (IV) injected tracer, no extravasation could be detected in the cerebral cortex. On the other hand, SF penetrated very rapidly into peripheral ganglia and into the epineurium and perineurium of large peripheral nerves. The penetration of SF into the endoneurium of large nerves was, however, much more restricted with tracer detectable within the endoneurium only at high doses and long survival times. Even in such cases, the level of SF fluorescence was much lower within nerve fascicles than in the epineurium and the perineurium, and a sharp gradient in fluorescence intensity persisted at the inner border of the perineurium. The extent of extravasation into the endoneurium varied markedly between different fascicles of the same nerve and between different nerves in the same animal.Experiments involving injection of high doses of SF adjacent to the nerve indicated relatively little movement of SF across the perineurium, which indicates that the observed accumulation of tracer within the endoneurium was the result of direct extravasation of SF from the endoneural blood vessels. Small nerve branches (< 100 μ in diameter) showed an earlier and more extensive penetration of SF into the endoneurium than large nerves like the sciatic, hypoglossal, or ventral tail nerve. This may be due to a diffusion of SF along the extracellular space of the endoneurium from nerve terminals where the perineurial barrier is open‐ended.In experiments involving IV injection of a solution containing both green fluorescent SF and red fluorescent Evans Blue (Evans Blue‐serum albumin complex, EBA = mol wt 69,000), the distribution of SF could be directly compared at various sites and sacrifice times to that of EBA, a much larger tracer. SF appeared more rapidly and extensively than EBA in the various compartments in ganglia and peripheral nerve. The distribution of EBA was the same as is typically seen when this tracer is injected alone, indicating that there was no change in vascular permeability associated with IV injection of SF.Since SF is of very small size, freely diffusible, nontoxic, and detectable at very low concentrations, it should be a useful complement to existing tracers. When tissues are processed according to the indicated procedure, one can obtain a very sensitive and reliable localization of this tracer which should be of value for studies in the nervous system concerning various pathological conditions associated with permeability alterations.
Tangential organization of thalamic projections to the neocortex in the mouse
Authors: Caviness Verne S. , Frost Douglas O. 
Published: December 2004

AbstractUsing the anterograde degeneration technique, we examine the tangential organization of a thalamofugal axon population (class I of Frost and Caviness, ′80) whose terminations are preferentially distributed to the middle tier (located in layers III and/or IV) of three radially separated tiers of thalamic projections to the neocortex. Less extensive data are also presented on the tangential organization of thalamofugal axon populations (class II of Frost and Caviness, ′80) that do not terminate preferentially in the middle tier, but that are otherwise heterogeneous with respect to their radial pattern of intracortical termination.The projections of class I axons are distributed to all neocortical fields with the possible exception of fields 13, 25, and 35. The class I projections to a given cortical field (with the possible exception of the cortex of the second somatosensory representation) originate in only one thalamic nucleus. The class I projections of an individual thalamic nucleus form a cortical representation of the nucleus that constitutes a “first order line‐to‐line” (topologic) transformation of the nuclear volume. The ensemble of class I projections forms a cortical representation of the corresponding thalamic regions that constitutes a “second order line‐to‐line” (non‐topologic) transformation of the thalamic volume.Class II axons project to all neocortical fields. Class II and class I projections contrast in that the class II projections of multiple thalamic nuclei overlap in the tangential plane of any given sector of the cortex. While the class II projections of the intralaminar nuclei and the widely projecting ventromedial nucleus are known to be topologically organized, the tangential organization of class II projections arising in other nuclei is incompletely understood.
Cytoarchitectonic sexual dimorphisms of the medial preoptic and anterior hypothalamic areas in guinea pig, rat, hamster, and mouse
Authors: Bleier Ruth , Byne William , Siggelkow Inge 
Published: December 2004

AbstractA cytoarchitectonic analysis is presented of a configuration of cells which extends through the medial preoptic and rostral part of the anterior hypothalamus of the guinea pig, rat, hamster, and mouse. Within that configuration, called here the sexually dimorphic nuclear complex of the medial preoptic‐anterior hypothalamic area (SDNC‐MPAH), there is nearly continuous variation in cellular distribution or packing density as one pro‐ceeds rostrocaudally, as well as variations between females and males at corresponding levels. The major cell groups comprising SDNC‐MPAH are the medial preoptic nucleus (MP) and the preventricular portion of the periventricular nucleus (Pep) rostrally, and the anterior hypothalamic nucleus (AH), anterior portion of periventricular nucleus, (Pea), and bed nucleus of stria terminalis (ST) caudally. The most striking cytoarchitectonic dimorphisms usually involve MP and AH. In all four species examined, MP is larger and, except for the mouse, appears to be more densely cellular in the female than in the male. Most prominently in the rat and guinea pig, AH is densely cellular throughout in the female, including the subependymal zone, whereas in the male AH lies at a distance from the third ventricle, separated from the ependyma by a cell poor zone.The significance of these findings may lie in the fact that the region exhibiting the sexual dimorphisms has been shown to be involved in the regulation of reproductive Functions which are sexually differentiated and developmentally influenced by the fetal or perinatal hormonal milieu in some species.
A quantitative anatomical study of the granule cell dendritic fields of the rat dentate gyrus using a novel probabilistic method
Authors: Desmond Nancy L. , Levy William B. 
Published: December 2004

AbstractThe granule cell dendritic fields of the adult rat dentate gyrus were analyzed quantitatively using a probabilistic method developed to correct dendritic length and segment number for dendrites cut during sectioning. Golgi‐impregnated, linearized hippocampi were sectioned serially in one of the three hippocampal planes. Three dendritic field parameters were quantified from camera lucida drawings of these dendritic fields: dendritic field spread, dendritic length, and the branching and termination patterns of dendritic segments.Granule cell dendritic fields resembled cones, their maximal extent occurring in the distal third of the molecular layer. The ratio of transverse to longitudinal dendritic field spread was greater than 1:1 for the dorsal leaf and crest regions, but close to or less than 1:1 for the ventral leaf.The probabilities of segment branching and termination were highly similar for transversely and longitudinally sectioned tissue. The probability of branching varied among dendritic orders and across the molecular layer for the same order. The probability of termination did not vary greatly across orders. Most nonbranching segments terminated adjacent to the hippocampal fissure.On the average, a granule cell had 2.23 first‐order dendrites that branched into a dendritic field containing seventh‐order dendrites. Total dendritic length, corrected for cut dendrites and projection errors, averaged 3,662 ± 88 μm. The somatic layer and proximal third of the molecular layer contained approximately 35% of this total length. The remainder, ca. 60%, was restricted to the distal two‐thirds of the molecular layer, the predominant termination zone of perforant path axons.These data provide a quantitative characterization of the rat granule cell dendritic fields. Implementation of the probabilistic correction method overcomes methodological problems common to quantitative Golgi studies. These data permit a more precise relationship to be drawn between dendritic architecture and granule cell physiology.
Neurons of the lateral and basolateral amygdaloid nuclei: A golgi study in the rat
Authors: McDonald Alexander J. 
Published: December 2004

AbstractNeurons in the lateral and basolateral nuclei of the rat amygdala were studied using Golgi‐Kopsch and rapid Golgi techniques. According to differences in perikaryal, dendritic, and axonal morphology, three main neuronal classes are recognized. Class I neurons, the predominant cell type in both nuclei, are large, spiny neurons that vary in size in different subdivisions of the lateral and basolateral nuclei. These neurons often have a pyramidal shape, exhibiting one or two thick “apical” dendrites and several thinner “basal” dendrites. Axons of class I neurons, which appear to pass out of the nucleus of origin, usually give off several collaterals that arborize modestly in the vicinity of the cell. Class II neurons are smaller, ovoid cells that comprise approximately 5% of impregnated neurons. These neurons are characterized by spine‐sparse dendrites and fairly dense local axonal arborizations. Class II neurons may be classified as multipolar, bitufted, or bipolar, depending on dendritic branching pattern. Another type of class II neuron, the amygdaloid chandelier cell, is recognized by virtue of its distinctive axon. The chandelier cell axon gives off numerous collaterals that form nestlike entanglements exhibiting clusters of axonal varicosities. Isolated chandelierlike axons of undetermined origin were observed forming multiple contacts with initial segments of class I axons. Several small, spherical class III neurons with short, varicose dendrites were observed. Axons branch profusely to form a dense tangle of collaterals in the vicinity of the cell. Both axons and dendrites establish numerous contacts with class I dendrites. This investigation, the first detailed Golgi study of the basolateral amygdala of the rat, reveals that the cytoarchitecture of this brain region in the rat is basically similar to that of the opossum and other mammals. Morphologic details described in this report should be useful in the interpretation of ultrastructural, immunocytochemical, and electro‐physiological studies of the basolateral amygdala.
Evidence for an orderly arrangement of optic axons within the optic nerves of the major nonmammalian vertebrate classes
Authors: Bunt Stuart M. , Horder T. J. 
Published: December 2004

AbstractThe pathways of selected optic axons were traced in representative urodele, anuran, teleost, reptile, and avian species by filling the fibers with HRP or by tracing, at the light and electron microscopic (EM) level, the degeneration caused by focal or optic nerve lesions.In all species it was shown that fibers retain retinotopic neighborhood relationships throughout their transit of the optic nerve. Additionally, inanurans, it was found that a subset of large diameter, myelinated fibers take up a random arrangement in the nerve. It is argued that retinotopic fiber organisation is a reflection fo contact guidance of axons during fiber outgrowth in the embryo and that this organisation could account for the arrival of fibers in orderly arrays at central nuclei during normal embryonic development.
Axonal branching in the projections from precerebellar nuclei to the lobulus simplex of the rat's cerebellum investigated by retrograde fluorescent double labeling
Authors: Payne J. N. 
Published: December 2004

AbstractThe projections to lobulus simplex and Crus I of the cerebellum from various brainstem nuclei have been examined in adult rats by using the retrograde fluorescent double labeling technique. True blue was injected into the lobulus simplex on one side and nuclear yellow on the other and the brainstem was examined for labeled neurons. The lateral reticular nucleus, pontine tegmental reticular nucleus, and nucleus praepositus hypoglossi were similar to the equivalent nuclei in other species but all contained double‐ as well as single‐labeled neurons and it was concluded that these nuclei have neurons whose axons branch to both sides of the cerebellum. More neurons in the rostral part of the lateral reticular nucleus were bilaterally projecting than in the caudal and the significance of this in relation to its afferents is considered.The individual neurons in the pontine nuclei, inferior olivary nucleus, and cuneate nuclei only appear to project to one side and the recent evidence for axonal branching of pontine neurons in the cat is discussed.
Fine structural studies on a type of somatostatin‐immurioreactive neuron and its synaptic connections in the rat neostriatum: A correlated light and electron microscopic study
Authors: Takagi H. , Somogyi P. , Somogyi J. , Smith A. D. 
Published: December 2004

AbstractSomatostain‐immunoreactive neurons in the rat neostriatum were studied by correlated light and electron microscopy using the peroxidase‐antipe‐roxidase immunocytochemical technique. Immunoreactivity was localized in neuronal perikarya and processes. The perikarya were of spindle or fu‐siform shape (average length 16.9 μm) and were found in all parts of the neostriatum. From each neuron there arose two to four straight immuno‐reactive dendritelike processes, which could frequently be traced as far as about 130 μm from their perikaryon. Immunoreactive varicose axonlike processes were occasionally found, some of which were proximal axons of identified immunoreactive cells. Nine of the light microscopically identified neurons showing somatostatin‐immunoreactivity were studied in the elec‐tron microscope; two of them had proximal axons with varicosities. Each neuron had an oval or elongated nucleus, which was always indented. These morphological features correspond well to those of certain “medium‐size aspiny” neurons classified by Golgi studies. Although the immunoreactive endproduct was diffusely located throughout the neuron, it was character‐istically located in the saccules and large granules (diameter 133 nm) of the Golgi apparatus, and large immunoreactive vesicles of similar size to those in the Golgi apparatus frequently occurred in all parts of axon. Very little synaptic input was found on the perikarya and dendrites of somato‐statin‐immunoreactive neurons. The perikarya and proximal dendrites re‐ceived both symmetrical and asymmetrical synaptic input, while the distal dendrites usually received boutons that formed asymmetrical contacts.The somatostatin‐immunoreactive boutons contained pleomorphic elec‐tron‐lucent vesicles (diameter 39.3 nm) and a few large immunoreactive granular vesicles; these boutons always formed symmetrical synapses. Their postsynaptic targets were dendritic shafts, spines, and unclassified dendritic profiles. On the other hand, the varicosities of identified proximal axons of somatostatin‐positive neurons did not form typical synapses, since they lacked clusters of small vesicles, but some of them were in direct apposition (via membrane specializations) to unlabelled perikarya or dendrites.It is concluded that somatostatin is a useful marker for a particular type of neuron in the neostriatum. The presence of somatostatin immunp‐reactivity in synaptic boutons is consistent with the view that somatostatin could be a neurotransmitter in the neostriatum.