bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fiber trajectories of olfactory bulb efferents in the hamster
Authors: Devor Marshall 
Published: January 2005

AbstractOlfactory bulb efferents sweep caudally over the surface of the piriform lobe in a broad fiber sheet. The internal organization of this axon population was analysed by topologically transforming the cortical surface from its in situ cylindrical form into an unrolled (flattened) map. The distribution of degeneration elicited by restricted bulb lesions and fiber transections was then reconstructed onto this map. Most of the projection cortex of the main olfactory bulb is innervated in a widespread, non‐topographic manner by axons that collect in the compact bundle of the lateral olfactory tract (LOT). LOT collateral branches bound for the prepiriform cortex veer laterally off the main trajectory of the tract at an angle of 50° or less. Thus, transection of discrete fiber populations leaves only a small wedge‐shaped pocket of totally denervated cortex distal to the cut. The medial half of the olfactory tubercle and the hippocampal rudiment receive their bulbar input along medially disposed fibers that do not join the LOT proper. The lateral half of the olfactory tubercle, however, receives an input from LOT fiber collaterals as well as these medial bulb efferents. Finally, much of the corticomedial amygdaloid complex receives fibers from the accessory olfactory bulb along a specialized subdivision of the LOT, the accessory olfactory tract. These observations are expressed in a schematic summary of the trajectories of olfactory bulb efferents as they appear in the unrolled map and in the more standard ventral view of the hamster brain.
An experimental inquiry into the central source of preganglionic fibers to the chick ciliary ganglion
Authors: Narayanan C. H. , Narayanan Y. 
Published: January 2005

AbstractDegenerative changes in the entire third nerve nucleus were studied following selective removal of the ciliary ganglion, usually of the right side, in day‐old chicks. The operated animals were allowed to survive three, six, nine, and twelve days after ciliary ganglionectomy. Retrograde degenerative changes proceed rapidly between three and nine days post‐operatively, and are strictly limited to the ipsilateral accessory oculomotor nucleus. The changes are at first observed in the medial division of the accessory oculomotor nucleus, followed by the lateral divisions of the accessory oculomotor nucleus. By nine days following the operation, both the divisions of the accessory oculomotor nucleus are virtually depleted of almost all neurons. The other components of the oculomotor complex were not affected at any stage by ciliary ganglionectomy. These observations provide conclusive evidence that the accessory oculomotor nucleus is indeed the avian homologue of the Edinger‐Westphal nucleus.
Pyramidal cell abnormalities in the motor cortex of a child with Down's syndrome. A Golgi study
Authors: Marin‐Padilla Miguel 
Published: January 2005

AbstractThe neuronal organization of the motor cortex of a 19‐month old child with Down's syndrome (mongolism) has been studied with the rapid Golgi method. This congenital syndrome, also known as 21 Trisomy is caused by a chromosomal abnormality consisting of the presence of an extra chromosome in the group 21. Various structural abnormalities have been found in the dendritic spines (postsynaptic structures) of the pyramidal neurons of the motor cortex of this child. The axo‐spinous synapses of these neurons are considered to be altered by these spine abnormalities. In addition, a peculiar form of intrinsic vacuolar change affecting the dendrites and scattered neuronal fragmentation and necrosis have also been found. At least three different types of abnormality involving the spines — (the unusually long spine, the very short spine and a reduction in the number of spines) — are recognized among the pyramidal cells of the motor cortex. It is postulated herein: that a basic anomaly, possibly related to the genetic disorder affects primarily some cortical neurons which undergo progressive degenerative changes terminating in cell fragmentation and death. The different spine abnormalities are considered to represent various developmental stages of the common genetic anomaly. These changes might be structural correlates of the motor incoordination and mental retardation which are characteristic of this genetic disorder, but, final conclusions should await the investigation of other cases with this or similar methods capable of demonstrating the normal as well as the abnormal structural organization of the human cerebral cortex.
A cytoarchitectonic atlas of the mouse hypothalamus
Authors: Broadwell Richard D. , Bleier Ruth 
Published: January 2005

AbstractA description of the organization, areas, and cell groups within the hypothalamus of the mouse is presented in detail. Photomicrographs of cellstained serial sections through the hypothalamus in frontal, sagittal and horizontal planes are included. The hypothalamus has been divided basically into medial and lateral parts with most well‐defined cell groups or nuclei lying within the medial subdivision and surrounded by diffuse collections of cells referred to as areas.The heterogeneity of cell types within most hypothalamic nuclei and areas has been emphasized with the consequent implications for heterogeneity of neuronal connections and of functions. Recently introduced neuroanatomical techniques permitting increased attention to the cellular level of organization have demonstrated precise connections and functional localization of cells within the hypothalamus. While cytoarchitectonic distinctions imply functional distinctions, morphological and experimental evidence suggest the existence also of systems of cells which transcend conventional cytoarchitectonic boundaries, the cells within each system being interconnected functionally or neuronally.
The neurons in the primate subthalamic nucleus: A Golgi and electron microscopic study
Authors: Rafols José A. , Fox Clement A. 
Published: January 2005

AbstractIn Golgi preparations of the adult monkey(Macaca mulatta) local interneurons and two varieties of principal neurons, radiating and elongated fusiform, are found in the subthalamic nucleus. The cell bodies of the radiating neurons have a few delicate, somatic spines some of which are occasionally bilobed and trilobed. Five to eight dendritic trunks give rise to branching, tapering dendrites, which may extend for over 400 microns. These dendrites are much thinner than the dendrites in the globus pallidus and the substantia nigra. Some neurons have many and some neurons have few dendritic spines. When numerous the dendritic spines are concentrated on the dendritic trunks and proximal dendrites. The relatively few elongated fusiform neurons are found not only in the capsule but also in the center of the nucleus. Most dendrites emerge from the opposite poles of their smooth surfaced cell bodies. They have a few dendritic spines. Some of these dendrites extend for more than 750 microns.In 1‐micron thick plastic sections lipofuscin granules are present in some but not all principal neuron cell bodies of the pig‐tail monkey(Macaca mulatta); but these granules are present in all principal neuron cell bodies of the pig‐tail monkey(Macaca nemestrina) and of the squirrel monkey (Saimiri sciureus).The local interneurons have small cell bodies and a few relatively long undulating dendrites. The dendrites have bulbous dendritic appendages of varying complexity and beaded axon‐ like processes. The dendritic appendages and axon‐like processes are more numerous distally and on the distal ends of the dendrites they form complex entanglements. Axons coming from the cell body have not been observed. The cell bodies of the local interneurons are identified in cresyl violet stained sections of the monkey (Macaca mulatta), in 1‐micron thick plastic sections and electron micrographs of the squirrel monkey(Saimiri sciureus). They have relatively large nuclei surrounded by a thin rim of cytoplasm rich in polyribosomes.
Impulse conduction in the myelinated giant fibers of the earthworm. Structure and function of the dorsal nodes in the median giant fiber
Authors: Günther Jorge 
Published: January 2005

AbstractThe dorsal openings in the myelin sheath of the median giant fiber (MGF) of the earthworm (Lumbricus terrestris L.) have been studied with electronmicroscopical and electrophysiological methods. The fine structure of the dorsal nodes (DN) resembles in many aspects the Ranvier nodes in vertebrate and crustacean nerve fibers. The nodal membrane directly faces the extracellular collagenous capsule of the ventral cord and displays a conspicuous electrondense undercoat. The myelin sheath of the paranode shows a characteristic differentiation into large desmosomal contacts.Recordings of the transmembrane and longitudinal surface currents along the dorsal side of the MGF during spike propagation support the view that an active inward current is restricted there to the DN. The inward current density in the DN reaches outstandingly high values similar to those measured in vertebrate nodes of Ranvier. The nodal activity can be blocked by application of tetrodotoxin and local anaesthetics. Local electrical stimulation of only one DN may suffice to elicit propagated actions potentials up and down the MGF. It is concluded that the dorsal nodes of the median giant fiber of the earthworm are highly specialized excitable structures mediating saltatory impulse conduction in these fibers.
Plasticity in the developing visual system: The effects of retinal lesions made in young rats
Authors: Lund Raymond D. , Lund Jennifer S. 
Published: January 2005

AbstractThe central visual pathways of the rat have been used as a model for investigating the significance of axonal interactions in mammalian neural development. Attention is restricted largely to the aberrant distribution of optic axons to the ipsilateral side of the brain and their distribution in the superior colliculus after early unilateral eye damage.The normal ipsilateral retinotectal pathway in pigmented rats appears as a series of patches located anteriorly and laterally in the stratum opticum, whereas in albino animals it is a small area lying anteromedially. In both, a few axons are often found at the extreme posterior border of the superior colliculus.After unilateral eye enucleation at birth, an aberrant ipsilateral pathway from the remaining eye arises at the optic chiasm. It originates from all parts of the retina and terminates in the ipsilateral superior colliculus in a topographic fashion such that the upper retina projects laterally and the lower retina, medially. The pathway is heaviest anteromedially (from lower temporal retina) and lightest posterolaterally (from upper nasal retina). There is always a heavy projection to the extreme posterior border of the superior colliculus. In only two animals of a large series was direct intertectal sprouting found.After partial retinal lesions, there is again an ipsilateral pathway from the unlesioned eye which fills the projection area of the lesion. As after total enucleation, the pathway arises from most of the ipsilateral retina, not just that region homotypic to the lesion site, being heaviest from the lower temporal and lightest (or deficient) from the upper retina. There is suggestion of ordering of the projection into the deafferented region in that the ipsilateral degeneration after lesions in the intact eye is compact but does not fill the gap in the crossed projection completely. There is also indication that some intact parts of the retina lesioned at birth may also project in an inappropriate retinotopic fashion to the deafferented region. The corticotectal pathway shows a normal map. Study of the ipsilateral retinotectal pathway indicates that the axons terminating at the extreme posterior border of the superior colliculus arise from the lower temporal retina.The results are interpreted as indicating that the aberrant uncrossed pathways after complete or local retinal lesions, compare very closely in most features. Both distribute to the deafferented area of the superior colliculus – in one, this is the whole surface, while in the other it is a small area. The fact that in the latter case axons are ending in quite inappropriate parts of the tectal map, may be explained more simply in terms of interactions between adjacent axons in the optic pathway rather than by an hypothesis involving a change in the cell labels across the tectal map.
Electron microscopic autoradiographic studies of gliogenesis in rat optic nerve I. Cell proliferation
Authors: Skoff Robert P. , Price Donald L. , Stocks Adelaine 
Published: January 2005

AbstractElectron microscopy and 3H‐thymidine autoradiographic techniques were used to study the fine structure of proliferating cells in developing rat optic nerve. Before the closure of the optic canal almost all of the cells incorporating radioactive thymidine are ventricular cells, but after closure (16 days of gestation) the vast majority are differentiating astroblasts or oligodendroblasts. Labeled astroblasts show a range in their degree of differentiation; some cells lack 90 Å cytoplasmic filaments while others have glial filaments and abundant cytoplasmic organelles. In contrast to astroblasts, all of the labeled oligodendroblasts are in the early stages of differentiation. The proliferation of oligodendroblasts starts at five days postnatal, approximately a day or two before the onset of myelination. During myelinogenesis a few of the labeled oligodendroblasts show presumptive connections to myelin sheaths. Microglial cells do not appear to play a major role in gliogenesis since they form less than 2% of all the labeled cells.The results of this study indicate that astroblasts and oligodendroblasts, rather than undifferentiated glioblasts, are the major source of macroglia. The finding that proliferating glia are in the process of differentiation agrees with recent studies which show that differentiated cells can divide.
Cells of origin of entorhinal cortical afferents to the hippocampus and fascia dentata of the rat
Authors: Steward Oswald , Scoville Sheila A. 
Published: January 2005

AbstractThe pathway from the entorhinal cortical region to the hippocampal formation has previously been shown to be comprised of two sub‐systems, one of which projects predominantly to the ipsilateral fascia dentata and regio inferior of the hippocampus proper, and a second which projects bilaterally to regio superior. The goal of the present investigation was to determine if these two pathways might originate from different cell populations within the entorhinal area. The cells of origin of these entorhinal pathways were identified by retrograde labeling with horseradish peroxidase (HRP).Injections which labeled the entorhinal terminal fields in both the fascia dentata and regio superior resulted in the retrograde labeling of two populations of cells in the entorhinal area. Ipsilateral to the injection, HRP reaction product was found in the cells of layer II (predominantly stellate cells) and the cells of layer III (predominantly pyramidal cells). Contralateral to the injections, however, the reaction product was found almost exclusively in the cells of layer III.With selective injections of the entorhinal terminal field in regio superior, only the cells of layer III were labeled, but these were labeled bilaterally. Selective injection of the entorhinal terminal field in the fascia dentata, however, resulted in the labeling of cells of layer II, but not of layer III, and these cells of layer II were labeled almost exclusively ipsilaterally. A very small number of labeled cells in layer II were, however, found contralateral to the injection as well.No labeled cells were found either in the presubiculum or parasubiculum following injections of the hippocampal formation. These cell populations were found capable of retrograde transport of HRP, however, since cells in both presubiculum and parasubiculum were labeled following HRP injections into the contralateral entorhinal area.These results suggest that the projections to the fascia dentata originate from the cells of layer II, while the projections to regio superior originate from the cells of layer III of the entorhinal region proper. The very slight crossed projection from the entorhinal area to the contralateral area dentata probably originates from the small population of cells in layer II which are labeled following HRP injections in the contralateral area dentata.
Neuroglial reactions secondary to wallerian degeneration in the optic nerve of the postnatal rat: Ultrastructural and quantitative study
Authors: Fulcrand J. , Privat A. 
Published: January 2005

AbstractWallerian degeneration has been studied in the optic nerve of the rat after unilateral enucleation. The operation was performed at the key stages 2, 5, 8, 20 days post natal (DPN), in order to compare the reactions of immature cells with those of their adult counterpart. Post operation delay (DPO) was staged from 1 to 204 days. The electron microscope study provided qualitative data relative to the function and the fate of the different cell lines, neuroglial and exogenous, in the reactive processes. Semi‐thin 1–μm sections stained with toluidine blue were used for the quantification of the different cell types at the various stages. Criteria of identification were those set‐up by Ling et al. ('73) for the corpus callosum and neighboring structures. In the three first key stages (2, 5, 8 DPN) the proliferation of glioblasts is reduced in amount and shortened in time when compared to the control. In the last one (20 DPO) a small peak over control value of glioblastic gliosis corresponds to a reactive gliosis already shown by other in the adult. Glioblasts are closely dependent upon the surrounding tissue for their ultimate fate. Microglia are exclusively involved in the phagocytosis of axonal and cellular debris, in the form of loaded macrophages. The comparison of the different percentage curves reflects the intensity and the timing of their reactions which are dependent upon the surrounding tissue. Reactive astrocytes, whose essential function is the formation of a scar, may participate in phagocytosis, especially in young animals, whose glial cells are not fully differentiated. They progressively constitute up to 90% of the glial population. Oligodendrocytes which are normally responsible for myelination, are only rarely involved in active phagocytosis; the oligodendrocyte line is either inhibited (key stages 2,5 DPN) or interrupted in its differentiation (key stage 20). It appears then that the presence of healthy axons is essential for the differentiation and even to a lesser degree the survival of the oligodendrocyte line. For the latter, the more differentiated the cell is the better it survives. Finally, hematogenous cells occur only in youngest animals, and in the close vicinity of the lesion. The influence of the enucleation upon gliogenesis and maturation of the optic nerve illustrates the interference between genetic and epigenetic factors and the interdependence of neurons and glia in the ontogenesis of the central nervous system. It exemplifies the great plasticity of the central nervous system in the youngest animals, thus validating our experimental onto‐pathologic approach.
The olivocerebellar projection studied with the method of retrograde axonal transport of horseradish peroxidase. V. The projections to the flocculonodular lobe and the paraflocculus in the rabbit
Authors: Hoddevik G. H. , Brodal A. 
Published: January 2005

AbstractHRP was injected in the flocculonodular lobe and the paraflocculus in the rabbit to determine the areas of the inferior olive which project onto these cerebellar regions. Following injections in the flocculus labeled cells occurred in the dorsal cap and the rostralmost tip of the medial accessory olive. Following injections in the nodulus labeled cells were likewise found in the dorsal cap, but in addition in the rostralmost part of the dorsomedial cell column and the adjoining part of the medial accessory olive. Injections in the dorsal paraflocculus gave rise to labeling in the rostrolateral part of the medial accessory olive, while injections in the ventral paraflocculus resulted in labeling in the principal olive, mainly in the lateral part of the ventral lamella. Injections in the lateral thired of the dentate nucleus gave rise to labeling mainly in the dorsal lamella of the principal olive.The results are discussed with reference to those obtained by previous authors. There are both similarities and discrepancies. It appears from what is known of afferents from areas mediating visual impulses to the inferior olive that the olivary areas projecting onto the flocculondular lobe, and possibly the dorsal paraflocculus, may mediate visual impulses to these lobules.
A histochemical study of the innervation of cerebral blood vessels in the turtle
Authors: Iijima Tadahiko 
Published: January 2005

AbstractSpecific histochemical techniques for the demonstration of noradrenaline and of acetylcholinesterase have been used to study the distribution of adrenergic and cholinergic nerves to the cerebral blood vessels of turtle, Geoclemys reevesii.The major and medium‐sized cerebral arteries were supplied with dense adrenergic nerve plexuses, the plexuses were particularly dense in the medium‐sized pial arteries of very thick vascular wall, indicating the functional significance of these arteries in the cerebral circulation. The parenchymal arterioles and capillaries were also supplied with adrenergic nerves.On the other hand, the cholinergic innervation was less dense than the adrenergic one and the acetylcholinesterase activity of the nerve fibres was remarkably weak. By contrast, the parenchymal small arterioles and capillaries exhibited heavy acetylcholinesterase activity on the vascular wall and, in addition, the capillaries were supplied with the well‐stained acetylcholinesterase‐positive nerve fibres. These fibres and also the adrenergic fibres associating with the capillaries appear to be of central origin. It is suggested that the cholinergic mechanisms in the parenchymal small vessels also play an important role in the cerebral circulation.The basophil leucocytes observed abundantly in the blood of turtle emitted an intensive greenish yellow fluorescence after formaldehyde gas‐treatment.
Experimental analysis of embryogenesis of cerebellum in rat. I. Subnormal growth following X‐ray irradiation on day 15 of gestation
Authors: Das Gopal D. 
Published: January 2005

AbstractRat embryos of 15 days gestation were exposed in utero to 170 R of X‐ray irradiation. Embryos collected 6 hours, 1, 2 and 3 days after irradiation, and animals of 2, 6, 15 and 30 days postanatal age were used for this study. Six hours after irradiation cells in the neuroepithelium and mantle layer along the roof of fourth ventricle were observed destroyed. Neuroepithelium showed only fragmentary regeneration during next two days, and it contributed to a small number of Purkinje cells. During postnatal development of cerebellum the external granular layer, the zone of proliferative cells that gives rise to neurons of postanatal origin, was found reduced. Other structures such as internal granular layer, molecular layer and medullary layer also were reduced. These multiple temporally sequenced developmental events resulted in a subnormal‐sized cerebellum. Various quantitative measures helped established that grossly the cerebellum in the X‐ray irradiated animals was aout half of that in the normal animals. Problems related to regeneration in the embryonic cerebellum, and to the factors determining the subnormal size of the adult cerebellum are discussed. Viewing this as an experimental approach to the study of neuroembryogenesis of cerebellum, the role of Purkinje cells in the regulationo f development of cerebellum is brought out.