bluuebunny/crossref_metadata_2025_split huggingface dataset:
The lamination and connectivity of embryonic cerebral cortex transplanted into newborn rat cortex
Authors: Chang Fen‐Lei F. , Steedman John G. , Lund Raymond D. 
Published: May 2005

AbstractSheets of frontal or occipital cerebral cortex were taken from embryonic day (E) 15 rat embryos and placed in shallow depressions made in the occipitoparietal region of newborn rats. These transplants developed normal patterns of lamination, which could be in an inverted orientation if the transplant itself was placed upside down. Irrespective of the cortical area of origin of the grafted tissue, the transplants consistently received projections from those host thalamic nuclei that were normally found to innervate the adjacent host cortex. This indicates that immature cortical tissue, up to at least E15, may not contain the information necessary to define the specific thalamocortical connections characteristic of individual areas. On the contrary, the observed input pattern may be the result of sprouting of fibers that normally innervated host cortical regions adjacent to the transplant. Similarly, callosal afferents to transplants seemed to be a direct extension of the callosal input to the host cortex immediately beneath the transplant.Results from HRP studies of callosal connections indicated that transplant efferents to the contralateral cortex are smaller in magnitude than their afferents. This may be related to the superficial location of the transplants, which may limit the access transplant efferents have to the white matter.This study suggests that, while the cortical lamination is largely determined intrinsically, the innervation of the cortex is influenced by the context in which it develops.
Cellular degeneration and synaptogenesis in the developing retina of the rat
Authors: Horsburgh Gwynn M. , Sefton Ann Jervie 
Published: May 2005

AbstractWe have investigated the time course and magnitude of cellular degeneration in the ganglion cell layer and the presumptive amacrine and bipolar regions of the inner nuclear layer during the development of the retina in the rat. Pyknotic profiles are present in the ganglion cell layer during the first 2 postnatal weeks, reaching peak numbers during the first 4 postnatal days (corresponding to the time of greatest loss of ganglion cells and their axons: Potts et al., ′82; Lam et al., ′82; Perry et al., ′83). Two observations suggest that the majority of pyknotic profiles present in the ganglion cell layer during the second postnatal week are not ganglion cells. First, following injection of kainic acid into one superior colliculus, degenerating ganglion cells in the contralateral retina are cleared within 24–48 hours. Therefore, since most ganglion cell and axon loss occurs within the first postnatal week, few of the pyknotic profiles present in the second week are likely to be ganglion cells. Second, the time course of cellular degeneration in the ganglion cell layer during the second postnatal week follows a very similar pattern to that seen in the presumptive amacrine sublayer of the inner nuclear layer. Such a correspondence suggests that two phases of cell death occur in the ganglion cell layer: during the first postnatal week the majority of dying cells are ganglion cells, and in the second, most cell death is due to a loss of displaced amacrine cells.In the inner nuclear layer pyknotic profiles are most numerous in the presumptive amacrine region on postnatal days 6 and 7, and in the presumptive bipolar region on day 10. Synaptogenesis in the inner plexiform layer occurs later but reflects the order of cell death. Thus, conventional (presumed amacrine) synapses were first observed on day 11 and synaptic ribbons (indicative of bipolar synapses) on day 13. These observations suggest that amacrine and bipolar cells initiate synapses only after their numbers have stabilized.
Stratified distribution of synapses in the inner plexiform layer of primate retina
Authors: Koontz Margaret A. , Hendrickson Anita E. 
Published: May 2005

AbstractDistributions of bipolar (B) and amacrine (A) synapses and postsynaptic ganglion cell (G) dendritic profiles in the inner plexiform layer (IPL) were analyzed in EM montages of monkey central and human foveal and peripheral retinae. Synapses and profiles were counted and plotted for each 5% interval of IPL, with 0% at the inner edge of the inner nuclear layer and 100% at the outer edge of the ganglion cell layer. In monkey and human retinae, both A and B synapses occur throughout the IPL, but the ratio of A to B synapses varies from 2:1 to more than 6:1.In the monkey central retina, four bands of A conventional synapses are concentrated at 15, 35, 60, and 80% depth. In the human foveal slope, there are two main A bands at 45 and 85%, whereas in the human periphery, there are five bands at 15, 35, 60, 75, and 90%. In both species, A processes containing large dense‐core vesicles are concentrated in three bands at 10–20, 50, and 80–90% depth, corresponding to previously described levels of peptides, dopamine, and GABA. B ribbon synapses are distributed fairly evenly throughout the IPL, with a suggestion of four broadly overlapping bands. Most B ribbons are presynaptic to one A and one G (B → A/G). In the human, there are significantly more B dyads with postsynaptic G's (B → A/G, B → G/G) in the fovea (91%) than in the periphery (66%), implying greater A cell processing peripherally. Also in the human, B terminals containing glycogenlike granules are concentrated in the outer half of the IPL, with agranular terminals in the inner half. Our results demonstrate multiple strata containing different types of synaptic contacts in primate IPL.
Changes of neurotensinlike immunoreactivity in the striatum of the cat after intrastriatal injection of kainic acid
Authors: Sugimoto Tetsuo , Itoh Kazuo , Yasui Yukihiko , Kamiya Hiroto , Uemura Yoshihiko , Mizuno Noboru 
Published: May 2005

AbstractIn the course of our study on the effects of kainic acid (KA) on neuropeptidelike immunoreactivity in striatal neurons, it was found that neurotensinlike immunoreactivity (NT‐LI) became visible immunohistochemically in cell bodies of some striatal neurons after injecting KA stereotaxically into the head of the caudate nucleus (Cd) of the cat. The adult cats injected with KA were allowed to survive for 1–56 days, and their brains were examined by the indirect immunoperoxidase method. In the intact Cd, NT‐LI was observed in axonal elements that accumulated to form irregularly shaped patches and displayed a discrete island‐and‐matrix pattern. At the site of KA injection, where neuronal cell loss and gliosis were produced, NT‐LI almost disappeared by the fourth day after KA injection. In parallel with these changes, many neuronal cell bodies with NT‐LI became visible in striatal regions surrounding the site of KA injection. Most of these neuronal cell bodies that showed NT‐LI were medium‐sized and extended thick dendrites with spines; spiny processes were rarely seen on the cell bodies. On the other hand, when a lesion was placed in the head of the Cd by thermo‐coagulation, no NT‐LI could be seen in cell bodies of striatal neurons. Thus it was presumed that NT‐LI in cell bodies of medium‐sized, spiny neurons of the cat striatum might be at a low level under normal conditions but enhanced in cell bodies of the neurons that survived the KA injections.
Radioautographic evidence for slow astrocyte turnover and modest oligodendrocyte production in the corpus callosum of adult mice infused with 3H‐thymidine
Authors: McCarthy G. F. , Leblond C. P. 
Published: May 2005

AbstractTo find out whether glial cells proliferate in the corpus callosum of adult mice, two series of experiments were carried out. The first one made use of 9‐month‐old “aged” male mice. Some of them were given 3H‐thymidine as a 2‐hour pulse to examine which cells became labeled and, therefore, had the ability to divide. Others were sacrificed after a continuous infusion of 3H‐thymidine for 30 days to examine whether the label would then appear in different cells. In other aged animals, the 30‐day infusion was followed by 60 or 180 days without 3H‐thymidine to determine whether cells retained or lost their label with time. A second series of experiments was carried out in 4‐month old “young adult” male mice to seek confirmation of the main conclusions.Following the 3H‐thymidine pulse given to aged mice, only immature glial cells were labeled. After a 30‐day infusion, 12.1% astrocytes and 1.1% oligodendrocytes were labeled, so that the net daily addition rate of astrocytes averaged 0.4% and of oligodendrocytes, 0.04%. In young adult mice, the rate after a 7‐day infusion averaged 0.9% for astrocytes and 0.08% for oligodendrocytes. However, when the 30‐day infusion into aged mice was followed by 60 and 180 days without 3H‐thymidine, the labeled astrocytes decreased to 5.3% and 0%, respectively, whereas the number of labeled oligodendrocytes did not change significantly.The interpretation of the results is that the immature cells present in the corpus callosum of mice continue dividing throughout life and their progeny give rise to astrocytes and oligodendrocytes. In the case of astrocytes, the production of new cells occurs in parallel with a loss, so that the astrocyte population turns over. In the case of oligodendrocytes, there is a small production of new, apparently stable cells.
Characterization of transient cortical projections from auditory, somatosensory, and motor cortices to visual areas 17, 18, and 19 in the kitten
Authors: Dehay Colette , Kennedy Henry , Bullier Jean 
Published: May 2005

AbstractWe have examined the anatomical features of ipsilateral transient cortical projections to areas 17, 18, and 19 in the kitten with the use of axonal tracers Fast Blue and WGA‐HRP. Injections of tracers in any of the three primary visual areas led to retrograde labeling in frontal, parietal, and temporal cortices. Retrogradely labeled cells were not randomly distributed, but instead occurred preferentially at certain loci. The pattern of retrograde labeling was not influenced by the area injected. The main locus of transiently projecting neurons was an isolated region in the ectosylvian gyrus, probably corresponding to auditory area A1. Other groups of transiently projecting neurons had more variable locations in the frontoparietal cortex.The laminar distribution of neurons sending a transient projection to the visual cortex is characteristic and different from that of parent neurons of other cortical pathways at the same age. In the frontoparietal cortex, transiently projecting neurons were located mainly in layer 1 and the upper part of layers 2 and 3. In the ectosylvian gyrus, nearly all the neurons are located in layers 2 and 3. In addition, a few transiently projecting neurons are found in layer 6 and in the white matter. Transiently projecting neurons have a pyramidal morphology except for the occasional spindle‐shaped cell of layer 1 and multipolar cells observed in the white matter.Anterograde studies were used to investigate the location of transient fibers in the visual cortex. Injections of WGA‐HRP at the site of origin of transient projections gave rise to few retrogradely labeled cells in areas 17, 18, and 19, demonstrating that transient projections to these areas are not reciprocal. Although labeled axons were found over a wide area of the posterior cortex, they were more numerous over certain regions, including areas 17, 18, and 19, and absent from other more lateral cortical regions. Transient projecting fibers were present in all cortical layers at birth. Plotting the location of transient fibers in numerous sections and at all ages showed that these fibers are not more plentiful in the white matter than they are in the gray matter. We found no evidence that the white/gray matter border constituted a physical barrier to the growth of transient axons.Comparison of the organization of this transient pathway to that of other transient connections is discussed with respect to the development of the cortex.
Distribution of cells containing mRNAs encoding substance P and neurokinin B in the rat central nervous system
Authors: Warden Marjorie K. , Young W. Scott 
Published: May 2005

AbstractThe family of tachykinins includes the neuropeptides substance P, neurokinin A, and neurokinin B. The distribution of substance P in the central nervous system has been studied immunohistochemically but the lack of specific antibodies has prevented similar studies of neurokinin B. Recent molecular genetics techniques have revealed the sequences for the complementary DNAs that code for the substance P and neurokinin B precursors. These results have permitted the design of specific probes to differentiate between substance P and neurokinin B transcripts by using in situ hybridization histochemistry. Our probes, 48‐base synthetic oligodeoxynucleotides labeled with 35S revealed extensive and distinct patterns of cell labeling for both substance P and neurokinin B throughout the rat central nervous system.The distribution of substance‐P‐mRNA‐containing cells that we observed confirmed and extended previous immunocytochemical descriptions. Cells containing transcripts for either tachykinin were present in the neocortex, hippocampus, olfactory bulb and associated areas, caudate‐putamen, hypothalamus, medial habenula, superior colliculus, central gray, and dorsal horn of the spinal cord. However, their distributions within these areas were usually quite different. Other areas contained only one tachykinin cell type: e.g., the nucleus of the lateral olfactory tract contained only neurokinin B cells whereas the raphe nuclei had only substance P cells. This study demonstrates the sensitivity and specificity of in situ hybridization histochemistry for mapping peptidergic neurons and lays the foundation for further investigations of the roles of these two tachykinins in the central nervous system.
Trigeminal alveolar nerve of the lower jaw in the cichlid Tilapia mariae: Evidence for continual axon generation and presence of exceptionally small myelinated axons
Authors: Hildebrand C. , Wiberg J. , Holje L. 
Published: May 2005

AbstractCross sections from the trigeminal alveolar nerve of the lower jaw in the cichlid Tilapia mariae were examined by electron microscopy. The nerve fibers are arranged in groups with a core of unmyelinated and small myelinated axons, surrounded by myelinated axons of varying sizes. The core contains large bundles of unmyelinated axons collectively ensheathed by circumferentially located Schwann cells, as well as smaller bundles of unmyelinated axons partly separated from each other by Schwann cell processes. Among the unmyelinated axons, occasional scattered profiles resembling growth cones are seen. The total number of axons in this tooth‐related nerve increases from approximately 1,500 to 5,000, as the animals grow in length from 4.5 to 21.5 cm. Some 24–49% of the axons are unmyelinated. The myelinated axons have maximum diameters of 1.0–3.0 μm, depending on body size. Most myelinated axons have diameters less than 1.0 μm and the smallest ones reach down to 0.3 μm. These results show that there is a continual addition of axons to the alveolar nerve of the lower jaw in Tilapia mariae and that the critical diameter for myelination in this peripheral nerve is similar to that typically found in the mammalian CNS.
Morphology of neurons in the basal forebrain nuclei of the rat: A Golgi study
Authors: Dinopoulos A. , Parnavelas J. G. , Uylings H. B. M. , van Eden C. G. 
Published: May 2005

AbstractThe neuronal cell types and their morphology in the nucleus basalis (NB), in the horizontal and vertical limbs of the diagonal band of Broca (NHL and NVL), and in the medial septal nucleus (MSN) were examined in Golgi‐impregnated material. Cells appeared as multipolar or oligopolar and displayed a variable dendritic morphology; their somata varied considerably both in shape and size. The dendrites of most cells were restricted within nuclear boundaries, although occasionally neurons located near boundaries, particularly cells in NHL, extended dendritic arbors into neighboring areas. Axons were rarely seen, but when they were found they were generally not impregnated beyond the initial segment and displayed no apparent preferential direction.Three types of cells common to each of the 4 nuclear groups could be identified on the basis of soma shape and dendritic form. The first type included large multipolar neurons with triangular or polygonal perikarya and typically 3–5 dendrites emerging from the poles of each cell. These cells were especially numerous in NB, NHL, and NVL, but were much less frequent in MSN. The second type comprised medium‐sized cells with round or oval somata and a small number, usually 2–3, of dendrites. They constituted a large percentage of the cell population in MSN, but were also encountered in NHL and NVL as well as in NB. The third type consisted of cells with fusiform or spindle‐shaped somata with usually single dendrites emanating from each pole of the cell. A rare but distinct type of spindleshaped neuron with dendrites bearing a rich complement of long and thin appendages was observed mainly in the ventral border of NHL.The present observations suggest that although the proportions and sizes of the 3 types of neurons vary between the 4 nuclei, neurons throughout the basal forebrain share common morphological characteristics.
Development of intracerebral dopaminergic grafts: A combined immunohistochemical and autoradiographic study of its time course and environmental influences
Authors: Abrous N. , Guy J. , Vigny A. , Calas A. , Moal M. Le , Herman J. P. 
Published: May 2005

AbstractThe aim of the study was to obtain a description of some aspects of the development of intracerebral dopaminergic grafts, namely, the time course of the glial reaction and its relation to cell division on one hand, and the development of graft‐originated innervation and its dependence on adequate matching of the implanted neurons and target site on the other hand. Cell suspensions obtained from the mesencephalon or hypothalamus of embryonic day (ED) 14 rat embryos were implanted into the striatum or lateral hypothalamus of adult rats following the destruction of the nigrostriatal system of the hosts. Animals were sacrificed at different postimplantation times, and the development of the graft was followed by immunohistochemistry by using antisera directed against tyrosine hydroxylase (TH) or glial fibrillary acidic protein (GFA). Furthermore, the existence of cell division at various times following implantation was examined by performing autoradiography on immunostained sections after prior intraventricular administration of 3H‐thymidine to the host. The first stage of the development of intracerebral grafts was characterized by the existence of intense cell division within the grafted tissue, lasting about 2 weeks, and also in the host tissue surrounding the graft, lasting only about 6 days. The cell division in the host tissue was paralleled by the existence of a strong glial reaction which, however, did not extend into the graft itself. Glial reaction in the host tissue gradually decreased at later times and disappeared by 4 weeks postimplantation without leaving behind a noticeable glial scar. The graft itself was, however, transiently filled with a population of reactive astroglial cells between 3 and 6 weeks postimplantation. Within grafts of mesencephalic tissue located in the striatum TH‐positive neurons were distributed evenly at short times postimplantation (2–6 days). At later time a compartmentation could be observed, with TH‐positive neurons being aligned along the graft‐host interface or clustered within the graft itself. Innervation of the host tissue by TH‐positive fibers increased between 1 and 6 weeks postimplantation. On the other hand, no compartmentation and reinnervation of surrounding host tissue was observed for intrahypothalamic grafts of mesencephalic tissue or intrastriatal grafts of hypothalamic tissue. This last observation indicates that adequate matching of implanted neurons and target tissue plays an important role in the development of intracerebral dopaminergic grafts.
New view of the organization of the pulvinar nucleus in Tupaia as revealed by tectopulvinar and pulvinar‐cortical projections
Authors: Luppino G. , Matelli M. , Carey R. G. , Fitzpatrick D. , Diamond Irving T. 
Published: May 2005

AbstractThe projections of the superficial layers of the superior colliculus to the pulvinar nucleus in Tupaia were reexamined by injecting WGA‐HRP into the tectum. The main result was finding two different patterns of terminations in the pulvinar nucleus: a zone remote from the lateral geniculate nucleus, which occupies the dorsomedial and caudal poles of the pulvinar nucleus, was almost entirely filled with terminals in every case irrespective of the location of the injection site; and a second division of the pulvinar nucleus, adjacent to the lateral geniculate nucleus, contained irregular patches—much more densely populated—and the distribution of patches varied from case to case. We call the first projection „diffuse”︁ and the patchy projection „specific.”︁ Next we injected several divisions of the extrastriate visual cortex to find the cortical target of each pathway. The diffuse path terminates in the ventral tenporal area (Tv). The specific path terminates in the dorsal temporal area (Td) and area 18. We speculated about the significance of the two pathways: the specific path may be responsible for the preservation of vision after removal of the striate cortex; the diffuse path may have an important place in the evolution of the visual areas of the temporal and occipital lobe. We argued that the target of the diffuse path is in a position to relate limbic and visual impulses and relay the product of such integration to the other visual areas, striate as well as extrastriate cortex.
Origins of descending projections to the medulla oblongata and rostral medulla spinalis in the urodeleSalamandra salamandra (amphibia)
Authors: Naujoks‐Manteuffel Christiane , Manteuffel Gerhard 
Published: May 2005

AbstractDescending projections to the medulla oblongata and rostral medulla spinalis have been examined in the urodele Salamandra salamandra with retrograde horseradish peroxidase tracing. Ipsilateral projections originate from the striatum and the nucleus ventrolateralis thalami and reach the medulla oblongata. The ipsilateral nucleus praeopticus magnocellularis reaches the medulla spinalis. The rostral part of the nucleus tuberculi posterioris projects to the ipsilateral medulla oblongata; its caudal part projects further caudally. Tectal efferents and the efferents of the nucleus praetectalis profundus project bilaterally, the nucleus praetectalis superficialis, nucleus mesencephalicus nervi trigemini, torus semicircularis, nucleus Darkschewitsch, and nucleus fasciculi longitudinalis medialis project ipsilaterally to the medulla oblongata. The nucleus mesencephalicus nervi trigemini, nucleus fasciculi longitudinalis medialis, and tectal efferents reach the rostral medulla spinalis. The nucleus ruber projects mainly via the contralateral dorsolateral funiculus to the medulla spinalis. A largely crossed medullary projection arises in the nucleus dorsalis tegmenti pars anterior, a bilateral projection arises in the nucleus dorsalis tegmenti pars posterior, and an ipsilateral projection arises in the nucleus ventralis tegmenti pars anterior. Cerebellar and statoacoustic efferents descend to the medulla spinalis. The nucleus reticularis isthmi, superior, medius and inferior as well as the nucleus raphes exhibit spinal trajectories. The nucleus vestibularis magnocellularis projects bilaterally, the nucleus vestibularis medialis projects ipsilaterally spinalward. The supposed nucleus descendens nervi trigemini descends mainly contralaterally. A small spinal projection arises in the nucleus tractus solitarii.The results indicate that salamander brains display elaborate descending connections which are similar to those in other vertebrates despite their scarcely differentiated neuronal cytoarchitecture.