bluuebunny/crossref_metadata_2025_split huggingface dataset:
Myeloarchitecture of the cerebellum of the chicken (Gallus domesticus): An atlas of the compartmental subdivision of the cerebellar white matter
Authors: Feirabend H. K. P. , Voogd J. 
Published: January 2005

AbstractA myeloarchitectonic atlas of the longitudinal (or mediolateral) subdivision of the cerebellum of the chicken (white Leghorn) was prepared from serial Häggqvist or toluidine‐blue‐stained sections of five animals. This myeloarchitectonic subdivision is based on the alternate occurrence of large fiber accumulations (LFAs) and small fiber areas (SFAs) in the cerebellar white matter and allows the distinction of a number of parasagittal fiber compartments, each of which consists of a medial LFA and a lateral SFA.The compartmental subdivision of the cerebellar white matter in mammals and birds derives its importance from the fact that essentially it corresponds to the organization of the afferent and efferent connections of the cerebellar cortex. The simple structure of the avian cerebellum makes it ideally suited for a complete description of its compartmental subdivision and may serve as a natural system of coordinates in future anatomical and physiological studies.The number of fiber compartments that can be counted in the chicken cerebellum on either side of the midline varies from six (in the narrowest folium I) to nine (in the widest folia IX and X) and is approximately the same as in mammals, in which a maximum of eight or ten compartments can be recognized. On the basis of the organization of its myeloarchitecture and the otherwise relatively scarce data on the organization of the connecitons of its cortex, it can, therefore, be postulated that the avian cerebellum is the homologue of the entire mammalian cerebellum. In addition, the present knowledge of the connections of the cerebellar cortex in birds indicates that the avian compartments 1—3 may correspond to the mammalian compartments A1, A2, and A3 (or X), whereas the avian compartment 4 or 5 (or both) may represent the mammalian B compartment. Lack of further anatomical data so far precludes conclusions on a possible homology between the avian compartments 6–9 and the mammalian C and D compartments.
Development of reticulospinal neurons of the zebrafish. I. Time of origin
Authors: Mendelson Bruce 
Published: January 2005

AbstractThe times of origin (birthdays) of identifiable types of reticulospinal (RS) neurons of the zebrafish (Brachydanio rerio) were determined in order to learn if differences in neuronal characteristics among cell types correlate with differences in their times of origin. The RS neurons are located in the midbrain and hindbrain and cell types can be identified by differences in their cell body sizes and positions, axonal projections, and dendritic arborizations (Metcalfe et al., J. Comp. Neurol. 251: 147–159, 1986). In this study, the birthdays of RS cells were determined by combining 3H‐thymidine autoradiography with horseradish peroxidase histochemistry.The RS neurons that were examined were generated between 7 and 28 h after fertilization. Each cell type had a specific time of origin. Dorsally located neurons were always generated earlier than ventral neurons present at the same axial level. Often, but not always, larger and more lateral neurons were born earlier than smaller and more medial ones. There was no overall rostrocaudal gradient of neuronal generation and no overall correlation between time of origin and axonal pathway. However, the times at which RS neurons are generated may be important with respect to the establishment of their characteristic dorsoventral positions in the brain.
Collateralization of descending pathways from the brainstem to the spinal cord in a lizard, Varanus exanthematicus
Authors: Wolters J. G. , De Boer‐Van Huizen R. , Donkelaar H. J. Ten , Leenen L. 
Published: January 2005

AbstractWith the multiple fluorescent retrograde tracer technique, the collateralization in the spinal cord of descending supraspinal pathways was studied in a lizad, Varanus exanthematicus. Fast Blue (FB) gels were implanted unilaterally in the spinal gray matter of the cervical enlargement and Nuclear Yellow (NY) gels were implanted ipsilaterally in two series of experiments in all spinal funiculi of the lumbar enlargement or in midthoracic spinal segments, respectively. All brainstem nuclei known to project to the spinal cord in reptiles were found to give rise to branching axons that may influence widely separate levels of the spinal cord. The number of double‐labeled FB‐NY cells varied in these brainstem nuclei from none to half the number of neurons projecting to the cervical enlargement. Highly collateralizing projections (expressed as the percentage of double‐labeled neurons, DL) were found to arise from the nucleus raphes inferior, the contralateral nucleus reticularis superior pars lateralis, the contralateral nuclei vestibulares ventromedialis and descendens, and the ipsilateral nucleus reticularis inferior pars ventralis. A lower percentage of DL neurons was noted for the contralateral nucleus ruber and bilaterally for the nucleus reticularis medius and nucleus reticularis inferior. Extensive brainstem projections directed to cervical and high thoracic spinal levels originate from the area lateralis hypothalami, the nucleus of the fasciculus longitudinalis medialis, the contralateral nucleus cerebellaris medialis, and from the nucleus tractus solitarii. Projections preferentially directed to midthoracic or lower levels of the spinal cord were found to arise from the ipsilateral locus coeruleus, the contralateral nucleus reticularis superior pars lateralis, the nucleus reticularis inferior pars ventralis, the nucleus reticularis inferior, and the nucleus raphes inferior. In contrast to findings in mammals, in Varanus exanthematicus the red nucleus, the nucleus vestibularis ventrolateralis, and certain parts of the reticular formation did not display a clearcut somatotopic organization.In general two different patterns of collateralization can grossly be discerned: (1) a gradual decrease of spinal coaterals caudalward, which can be interpreted as a certain specificity of such projections; and (2) a constant number of collateral nerve fibers throughout the spinal cord that can be interpreted as either a nonspecific or, in contrast, a highly specific system, focussed exclusively on the cervical and lumbar enlargements.
Regional specialization in synaptic input and output in an identified local nonspiking interneuron of the crayfish revealed by light and electron microscopy
Authors: Kondoh Y. , Hisada M. 
Published: January 2005

AbstractLateral inhibition of several mechanosensory interneurons in the crayfish terminal ganglion is mediated by a pair of identified local nonspiking interneurons called local directionally selective (LDS) interneurons. The ultrastructure and synaptic distribution of these interneurons were investigated by using intracellular labeling with horseradish peroxidase for electron microscopy.The LDS interneuron has bilateral, asymmetric arborizations. They are connected by a thick transverse neurite on which no synapses are made. The neurites on the side ipsilateral to the cell body are smooth and receive almost entirely input synapses. On the other hand, the contralateral neurites have prominent numerous swellings or varicosities from which many short fine spines arise, with intermingled input and output synapses. Both synapses, however, are not always associated with varicosities and spines. Presynaptic neurites of the LDS interneuron contain only round agranular synaptic vesicles in the vicinity of synaptic specializations. These morphological findings correlate well with the physiology of this interneuron: it is functionally polarized to receive input on one side (ipsilateral to the cell body) of the ganglion and convey it to the other side.
3H‐nicotine and 125I‐alpha‐bungarotoxin‐labeled nicotinic receptors in the interpeduncular nucleus of rats. I. Subnuclear distribution
Authors: Hamill Geoffrey S. , Clarke Paul B. S. , Pert Agu , Jacobowitz David M. 
Published: January 2005

AbstractThe distribution of nicotinic receptors within the interpeduncular nucleus (IPN) was determined in male rats following in vitro labeling with the cholinergic ligands 3H‐nicotine and 125I‐alpha‐bungarotoxin (BTX). Autoradiographic images of two rostrocaudal levels of IPN were analyzed by computer‐assisted densitometry and the optical density contributed by displaceable labeling was determined in the rostral, central, intermediate, and lateral subnuclei.3H‐nicotine labeling density within the four subnuclei differs significantly at both levels of IPN. The greatest density of labeling is localized in the rostral subnucleus, followed in order of diminishing density by the central, intermediate, and lateral subnuclei. Labeling within the rostral subnucleus is prominently localized within its central zone. In the central subnucleus, a dense concentration of binding sites is apparent in the middle region, adjacent to less dense vertically oriented columns; 3H‐nicotine binding sites in the lateral subnuclei appear to be most concentrated medially, adjacent to the intermediate subnuclei.125I‐BTX labeling density within the four subnuclei also differs significantly at both levels of IPN. The greatest density of labeling is found in the rostral subnucleus, followed in order of decreasing density by the lateral, central, and intermediate subnuclei. The ovoid regions of the rostral subnucleus contain dense 125I‐BTX labeling. In the lateral subnuclei, 125I‐BTX binding appears to be predominantly along the lateral margins of the subnucleus.The present data indicate that the IPN contains two distinct populations of putative cholinergic nicotinic receptors identified, respectively, by 3H‐nicotine and 125I‐BTX labeling. Each population of labeled receptors is uniquely localized in patterns that suggest differences in density within and across subnuclei.
Development of anomalous retinal projections to nonvisual thalamic nuclei in syrian hamsters: A quantitative study
Authors: Frost Douglas O. 
Published: January 2005

AbstractWhen two of the principal targets of retinofugal axons, the superior colliculus and dorsal nucleus of the lateral geniculate body, are ablated in newborn hamsters and the somatosensory (ventrobasal) or auditory (medial geniculate) thalamic nuclei are partially deafferented, the optic axons form permanent, abnormal connections in the latter nuclei. The lateral posterior nucleus of the operated hamsters also receives an anomalously large retinal projection. Here, we report on the results of a quantitative study that was undertaken in order to elucidate how these abnormal connections are formed.In normal, newborn hamsters, there is a transient retinal projection to the ventrobasal nucleus that disappears 3‐‐4 days postnatally. Our quantitative data show that postoperatively, the volume of the retino‐ventrobasal projection increases proportionately more than the volume of the ventrobasal nucleus so that the retino‐ventrobasal projection in operated adult hamsters is due both to the stabilization of the normally transient projection and to a reactive sprouting that increases the size of the projection. The retino‐medial geniculate projection arises de novo by reactive sprouting of optic tract fibers that normally pass over and through the nucleus; in unoperated hamsters, terminating projections are never seen at any age. The quantitative data also show that the anomalously large retino‐lateral posterior projection is due almost entirely to the reactive sprouting of the normal projection and/or normal fibers of passage that are already present on the day of birth, although it is possible that a minor component can be attributed to the stabilization of a small population of normally transient retino‐lateral posterior axons.The present results demonstrate that the transient retino‐ventrobasal axons in normal, newborn hamsters are capable of making permanent connections with ventrobasal neurons. This finding raises the important question of the cellular mechanisms that determine whether immature neuronal connections are stabilized or eliminated. The results also suggest that during both normal and abnormal development, the choice of a target by growing axons may depend upon the axons being in proximity to a potential terminal site just at the time when that site is capable of receiving afferents.
Grafted septal neurons form cholinergic synaptic connections in the dentate gyrus of behaviorally impaired aged rats
Authors: Clarke D. J. , Gage F. H. , Nilsson O. G. , Björklund A. 
Published: January 2005

AbstractA group of aged, behaviorally impaired rats received suspension grafts of fetal septal‐diagonal band tissue into the otherwise intact hippocampal formation. Three months after grafting, behaviorally recovered rats were studied by immunocytochemistry by using monoclonal antibodies to choling acetyltransferase (ChAT) and electron microscopy. The innervation of the host dentate gyrus by graft‐derived ChAT‐positive fibres was unmasked by acute removal of the intrinsic septal cholinergic innervation by fimbriafornix transection 5‐‐7 days before perfusion. The pattern of termination and ultrastructural connectivity were compared with previous results obtained from both young nonoperated control animals and a group of young rats with intrahippocampal septal grafts that had been subjected to denervation of the intrinsic cholinergic input at the time of transplantation.Graft‐derived, ChAT‐immunoreactive terminals formed abundant synaptic speciliazations with neuronal elements in the host dentate gyrus. The predominant postsynaptic target (about 65% of all boutons) was dendritic shafts, whereas about 20% of the boutons contacted dendritic spines. Very few synapses onto neuronal perikarya were found in the grafted aged rats. In some of these cases, however, it was possible to identify the target as dentate granule cells. This situation is very similar to that seen in young control rats but significantly different than the distribution observed in the denervated young grafted group, where axosomatic contacts predominated.The results indicate that the graft‐induced behavioral improvement seen in the aged rats may depend on the formation of functional cholinergic graft connections with neuronal elements in the host hippocampal formation.
Morphological alterations in subcortical vibrissal relays following vibrissal follicle destruction at birth in the mouse
Authors: Hámori J. , Savy C. , Madarász M. , Somogyi J. , Takács J. , Verley R. , Farkas‐Bargeton E. 
Published: January 2005

AbstractMorphological modifications of two subcortical vibrissal relays were analyzed, following destruction of vibrissal follicles in newborn mice. The volume of the nucleus interpolaris (NI) of the trigeminal nuclear complex in the brainstem decreased by 33%, while the number of its neuronal perikarya decreased only moderately. Vibrissal deafferentation caused no shrinkage of the ventrobasal complex (VB). In the damaged medial vibrissal part of VB (VBm), however, neuronal density was higher than normal, indicating the prevention or retardation of physiologically programmed cell death in the afferentation deprived thalamic somatosensory relay station. It is suggested that the difference in neuron density produced by deafferentation is related to the states of maturation at birth of the two subcortical vibrissal relays.Following vibrissal deafferentation the basic organization of the synaptic neuropil appeared to be similar to the control. Quantitative electron microscopic (EM) analysis revealed, however, an increased number of axon terminals with ovoid synaptic vesicles in both deafferented relay stations. The increased density of gamma‐aminobutyric acid (GABA)‐immunostained boutons observed in the VBm following vibrissal deprivation suggested a compensatory increase most probably of the inhibitory axon endings.Quantitative EM analysis also provided evidence that many or most of the specific afferent terminals in the damaged VBm were not identical with but were substitutes for the original “vibrissal” specific afferents. Forty percent of all “specific” afferents were shown to be modified corticothalamic terminals. The modification and the resemblence of some cortical endings to specific afferents demonstrated the morphogenetic plasticity of synaptogenesis in these terminals during development as well as the importance and inductive potential of the postsynaptic target in the differentiation of presynaptic axon terminals.
Stages in the structural differentiation of retinal ganglion cells
Authors: Maslim Juliani , Webster Maree , Stone Jonathan 
Published: January 2005

AbstractUsing a cultured wholemount technique we have studied the morphological differentiation of ganglion cells in the retina of the rat and cat, during normal development. In both species the differentiation of ganglion cells begins in embryonic life, before embryonic day (E) 17 in the rat and E36 in the cat.It is useful to describe the morphological differentiation of ganglion cells as occurring in three stages. In the first stage, each germinal cell becoming a ganglion cell extends an axon into the fibre layer of the retina and towards the optic disc, and the soma of the cell moves towards the ganglion cell layer. As the soma approaches the ganglion cell layer, the processes that attach its poles to the inner and outer surfaces of the retina are withdrawn.When the soma reaches the ganglion cell layer, a stage of active dendritic growth begins, which lasts until shortly before birth in the cat and until several days after birth in the rat. The cell extends stem dendrites that branch profusely and are commonly tipped by growth cones. The major morphological classes of ganglion cell become distinct in the latter part of stage 2, as do the centroperipheral gradients in ganglion cell size apparent in the cat.During the third stage, the dendritic trees of ganglion cells no longer branch or extend by means of active growth cones. Very considerable growth of all parameters of the cell (soma size, dendrite calibre and length, axon calibre) occurs nevertheless, presumably by interstitial addition of membrane throughout the cell.
Map of retinal position onto the cross section of the optic pathway of goldfish
Authors: Bernhardt R. , Easter S. S. 
Published: January 2005

AbstractThe position of a retinal cell is defined by the two polar coordinates: r, the distance from the optic disc, and θ the angular (or clock‐face) position. Axons of similar θ value were labeled by the punctate application of horseradish peroxidase (HRP) to optic axons in the retina, and axons of similar r‐value were labeled by the application of this same marker to a tectal fascicle. Labeled axons were traced in serial transverse sections of the optic pathway from the retina to the tectum to learn the map of the retinal surface onto the cross section of the pathway. Retinas were flat‐mounted and treated for HRP to show the retinal origins of the labeled axons.Axons of similar r were clustered together, and the fraction of the pathway's cross‐sectional area occupied by the cluster was about the same as the fraction of the retinal area occupied by the group of labeled somata. Axons of similar θ were also clustered, but the fraction of the cross‐sectional area they occupied was larger than the fraction of retinal area occupied by their somata. The geometry of the clusters of labeled axons depended on the proximodistal location in the pathway. Near the retina both were stripshaped, but the location and orientation of the strip varied. Both an r‐strip and a θ‐strip were labeled in some pathways by dual applications of HRP; the two strips were mutually orthogonal at all levels.Each of r and θ mapped onto a separate axis. The axons from most peripheral retina (largest r) were everywhere adjacent to the pia, and axons of progressively more central retina (smaller r) were progressively more separated from the pia (except in the nerve, where the secondary fasciculation complicates the geometry by wrapping old axons in new pia). The map of the circular variable, θ onto a line, required a discontinuity, the location of which differed, depending on the proximodistal level. From the retina to the chiasm, the discontinuity was at the ventral retinal radius (i.e., the right retinal clock‐face positions were ordered 6‐9‐12‐3‐6 o'clock across the line); just central to the chiasm, the fibers reordered to put the discontinuity at the nasal radius (clock‐face positions ordered 3‐6‐9‐12‐3); at the brachial bifurcation, the 3‐6‐9 half turned dorsally, the 9‐12‐3 half, ventrally.The results are discussed in the context of the growth of the pathway and compared with similar organizational plans in the optic pathways of other vertebrates.
Organization of corticogeniculate projections in the turtle, pseudemys scripta
Authors: Ulinski Philip S. 
Published: January 2005

AbstractThe efferent pathways from the visual cortex to the dorsal lateral geniculate complex of turtles have been studied by using the orthograde and retrograde transport of horseradish peroxidase (HRP). Injections of HRP in the lateral thalamus retrogradely label neurons throughout the visual cortex. The majority of labeled neurons have somata in layer 2 of the lateral part of dorsal cortex (D2); a minority have somata in layer 3. Labeled neurons in layer 2 tend to have vertically oriented, fusiform somata and dendrites that ascend into layer 1. Labeled neurons in layer 3 have fusiform somata and dendrites, both oriented horizontally. Injections of HRP in visual cortex orthogradely label corticofugal axons. Those projecting to the lateral geniculate complex course laterally from the visual cortex, pass through the striatum (occasionally bearing varicosities), and enter the diencephalon in the ventral peduncle of the lateral forebrain bundle. Individual axons leave the ventral peduncle and run dorsally in the transverse plane, entering the dorsal lateral geniculate complex from its ventral edge. They continue dorsally, principally in the cell plate of the geniculate complex, where they bear varicosities.