bluuebunny/crossref_metadata_2025_split huggingface dataset:
Contralateral thalamic projections predominantly reach transitional cortices in the rhesus monkey
Authors: Dermon C. R. , Barbas H. 
Published: January 2005

AbstractConnections between the thalamus and the cortex are generally regarded as ipsilateral, even though contralateral connections exist as well in several adult mammalian species. It is not known however, whether contralateral thalamocortical projections reach particular cortices or whether they emanate from specific nuclei. In the rhesus monkey different types of cortices, ranging from transitional to eulaminate, vary in their cortical connectional pattern and may also differ in thier thalamic connections. Because olfactory and transitional prefrontal cortices receive widespread projections, we investaged whether they are the target of projections from the contralateral thalamus as well. With the aid of retrograde tracers, we studied the thalamic projections of primary olfactory (olfactory tubercle and prepiriform cortex) and transitional orbital (areas PAPP, Pro 13) and medial (areas 25, 24, 32) areas, and of eulaminate (areas 11, 12, 9) cortices for comparison.To determine the prevalence of neurons in the contralateral thalamus, we compared them with the ipsilateral in each case. The pattern of ipsilateral thalamic projections differed somewhat among orbital, medial, and olfactory cortices. The mediodorsal nucleus was the predominant source of projections to orbital areas, midline nuclei included consistently about 25% of the thalamic neurons directed to medial transitional cortices, and primary olfactory areas were distinguished by receiving thalamic projections predominantly from neurons in midline and intralaminar nuclei.Notwithstanding some broad differences in the ipsilateral thalamofrontal projections, which appeared to depend on cortical location, the pattern of contralateral projections was thalamus were noted in midline, the magnocellular sector of the mediodorsal nucleus, the anterior medial and intralaminar nuclei, and ranged from 0 to 14% of the ipsilateral; they were directed primarily to olfactory and transitional orbital and medical cortices but rarely projected to eulaminate areas. Several thalamic nuclei projected from both sides to olfactory and transitional areas, but issued only ipsilateral projections to eulaminate areas. Though ipsilateral thalamocortical projections predominate in adult mammalian species, crossed projections are a common feature in development. The results suggest differences in the persistence of contralateral thalamocortical interactions between transitional and eulaminate cortices. © 1994 Wiley‐Liss, Inc.
Immunocytochemical localization of the GABAA receptor in the cerebral cortex of the lizard Psammodromus algirus
Authors: Guirado Salvador , Dávila Jose Carlos 
Published: January 2005

AbstractThis study examined the distribution and localization of the γ‐aminobutyric acid (GABA)A receptor in the brain cortex of a reptile by light and electron microscopy, to test whether cortical GABA inhibition is mainly mediated through the GABAA receptro complex. We used preembedding immunocytochemistry and a monoclonal antibody, raised against the receptor complex, that recognizes the β2 and β3 subunits of the receptor. GABAA receptors were distributed throughout the entire cerebral restricted to the plexiform layers of the cortex as seen by light microscopy. This granular aspect of the immunoreactivity most likely corresponds to the immunopositive dendritic and axonal profiles observed under the electron microscope. Some neurons in the medial and lateral cortices displayed pathches of immunoreactivity along the cell body and processes, and as a result their morphology was outlined. We discuss the possibility that these neurons were GABAergic as well. The immunocytochemical data demonstrate that the distribution and localization of GABAA receptors in discrete regions of the reptilian cerebral cortex resemble that of parts of the hippocampal formation of humans and rats, suggesting that the basic configuration of the GABA system in these regions is conserved. © 1994 Wiley‐Liss, Inc.
Expression of Mu opioid receptor mRNA in rat brain: An in situ hybridization study at the single cell level
Authors: Delfs Jill M. , Kong Haeyoung , Mestek Anton , Chen Yan , Yu Lei , Reisine Terry , Chesselet Marie‐Françoise 
Published: January 2005

AbstractThe mu (μ) opioid receptors, which mediate the effects of morphine, are widely distributed in brain. We have examined the distribution of mRNA encoding a μ opioid receptor in rat brain with in situ hybridization histochemistry at the single‐cell level to obtain information about the cell types synthesizing this receptor. Only neurons, not glia, were labeled in discrete brain regions. High levels of labeling were detected in the thalamus, striosomes of the caudateputamen, globus pallidus, and brain regions involved in nociception, arousal, respiratory control, and, possibly, addiction. The general distribution of the receptor mRNA paralleled that of μ opioid binding sites with some notable exceptions. These include the cerebral cortex, which contains binding sites, but very few labeled neurons. No labeling was observed in the cerebellum, a region devoid of μ binding sites. Three main findings emerged from these experiments: (1) the mRNA was present in regions mediating both the therapeutic (analgesia) and the unwanted (respiratory depression, addiction) effects of morphine, (2) the mRNA was very densely expressed by neurons known to receive dense enkephalin‐containing inputs, and (3) the dissociation between the presence of binding sites and absence of mRNA in some brain regions supports a presynaptic localization of μ opioid receptors in these areas. Alternatively, other subtypes of μ opioid receptors may be encoded by a different mRNA. These results provide new insights into the receptor types and neuronal circuits involved in the effects of endogenous opioids and morphine. © 1994 Wiley‐Liss, Inc.
Ontogenesis and taste bud cell turnover in the chicken. I. Gemmal cell renewal in the hatchling
Authors: Ganchrow Donald , Ganchrow Judith R. , Romano Rafael , Kinnamon John C. 
Published: January 2005

AbstractTaste bud cell turnover rate was examined in oral epithelium of the precocial chick, which at hatching contains the adult complement of taste buds. Forty newly hatched chicks received single or double pulse injections of tritiated thymidine (specific activity was 6.7 Curies/ millimole; dosage was 0.5 micro Curies/g body weight, intraperitoneally). Anterior mandibular epithelium was processed for light microscopic autoradiography at 2 and 16 hours, as well as 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18, and 20 days after the initial pulse. In a coded and randomized procedure, the section (7 μm) through the bud's center was selected for counting > 6 silver grains over round‐clear and gracile‐dense gemmal cell nuclei. The mean number of labelled cells/bud varied significantly (P ⩽ 0.01) during the first four posthatch days, yielding the fastest gemmal cell turnover rates (3.4–4.4 days) yet reported in vertebrates.Average bud diameter also significantly changed during the first four posthatch days, and was reflected in shifts of the distribution of 40–69 μm and > 70 μm diameter buds. Both an increase in labelled bud cells and bud diameter during the first two posthatch days may reflect high proliferation rates in initially maturing buds. Subsequent decrease in bud diameter between 2 and 3 days postinjection may indicate splitting of large‐diameter (≥ 70 μm) buds and/or normal bud cell death due to failure of sensory afferentation. Bud‐splitting alone, however, cannot account for significant decreases in bud cell label which did not occur before 4–6 days postinjection. © Wiley‐Liss, Inc.
Antibodies against different forms of GnRH distinguish different populations of cells and axonal pathways in a urodele amphibian, Taricha granulosa
Authors: Muske Linda E. , Moore Frank L. 
Published: January 2005

AbstractNeurons immunoreactive to the peptide hormone gonadotropin‐releasing hormone (GnRH) have been identified in the posterior diencephalon or anterior midbrain of diverse vertebrates. These cells are located caudal to the more well‐characterized GnRH neurons in the nervus terminalis and septo‐preoptic area, and are believed to express one or more of the nonmammalian forms of the GnRH. The present study utilized immunocytochemical techniques to determine whether the posterior GnRH group is present in a urodele amphibian, the newt Taricha granulosa. Antibodies directed against different molecular forms of GnRH were used to evaluate the immunological properties of GnRH‐containing neurons in amphibians. An antibody selective for mammalian GnRH labeled perikarya in the nervus terminalis (terminal nerve) and septo‐preoptic region, as described previously. Thick fibers that arise from terminal nerve and septo‐preoptic neurons project mainly to the median eminence, medial pallium and habenula. An antibody selective for chicken GnRH II labeled cell bodies in the paraventricular organ and posterior tubercle of the caudal diencephalon, and thin fibers that project widely throughout the central nervous system. Region‐specific staining with different GnRH antibodies supports the interpretation that different molecular forms of GnRH are expressed by neuroanatomically distinguishable systems. © 1994 Wiley‐Liss, Inc.
Imaging of individual normal and regenerating optic fibers in the brain of living adult goldfish
Authors: Danks Anne M. , Kim Patricia , Wang Ziren , Meyer Ronald L. 
Published: January 2005

AbstractRetinal arbors in the tectum of living adult goldfish were imaged to determine whether the structural remodelling and refinement that occurs during development continues in adulthood. Individual optic fibers were labelled by making small injections of the lipophilic fluorescent dye DiI into ventral retina and viewing the exposed tectum through a fluorescence microscope equipped with a cooled CCD camera. Arbors were imaged in the living fish every 30–60 minutes for up to 7 hours.Normal adult goldfish showed no evidence of arbor remodelling during this period, though dynamic movements of varicosities present along axon segments were observed. For comparison, regenerating optic fibers were similarly imaged in fish that had undergone optic nerve crush 2–6 weeks previously. In these fish, dynamic structural changes were seen, including branch remodelling, extension and retraction of growth cones, and movement of varicosities. © 1994 Wiley‐Liss, Inc.
Quantitative analyses of postembryonic hair cell addition in the otolithic endorgans of the inner ear of the european hake, merluccius merluccius (gadiformes, teleostei)
Authors: Lombarte Antoni , Popper Arthur N. 
Published: January 2005

AbstractBony fishes add sensory hair cells to the saccule and lagena of the ear for at least several years after hatching. However, it is not known whether hair cell proliferation occurs for the whole lifetime of an animal, whether proliferation occurs in all endorgans of the ear, or whether the rate of proliferation is the same in all of the endorgans. To obtain answers to these questions, the extent of postembryonic hair‐cell proliferation was determined in the saccule, lagena, and utricle of the ear in the European hake, Merluccius merlaccius, for fish ranging from 7 to 75 cm in total length (6 months to 9 years of age). Results demonstrated that hair‐cell addition continued throughout this period in all three otic endorgans, although endorgan size was proportionally greatest in smaller animals. Of the three endorgans, cell addition was greatest in the saccule. Moreover, far more cells were added to the caudal end of the saccule than to the rostral end. Each saccule of the largest hake had over 900,000 hair cells. It is estimated that each saccule adds approximately 110,000 new hair cells each year (or 302 cells/day) over the life span of the fish studied. A significant number of small ciliary bundles, thought to represent newly proliferated hair cells, was found throughout each endorgan, and the number of such bundles declined as the rate of hair cell proliferation decreased. The results demonstrate that extensive proliferation occurs in all three otolithic endorgans of the ears in a fish and that such proliferation continues for virtually the whole life of the animal. The functional significance of this addition is not known. © 1994 Wiley‐Liss, Inc.
Dendritic development of dentate granule cells in the absence of their specific extrinsic afferents
Authors: Zafirov Silvana , Heimrich Bernd , Frotscher Michael 
Published: January 2005

AbstractDendrites and spines are postsynaptic structures that develop in association with presynaptic fibers. Recent studies have shown that granule cells of the fascia dentata survive in slice cultures and differentiate in a manner known from in situ studies. However, all extrinsic afferent fibers are absent under culture conditions. In the present study, we study whether dendrites and spines of granule cells in slice cultures differentiate normally, although they are not contacted by their normal layer‐specific afferents.Slices of hippocampus were prepared from rat pups at the day of birth. After 5, 10, 15, and 20 days of incubation, granule cells in these cultures were Golgi impregnated. For comparison, perfusion‐fixed hippocampal sections of 5‐, 10‐, 15‐, and 20‐day‐old rats were impregnated the same way. Our results show that the total density of spines on granule cell dendrites in culture increased as in perfusion‐fixed animals. However, after 20 days of incubation, the absolute number of dendritic spine on cultured neurons was reduced because of a reduction of peripheral dendrites. This reduction was accompanied by an increase in the number of stem dendrites originating from the perikaryon. The density of spines on these proximal dendrites was larger in cultured granule cells than in controls.Our results suggest that the lack of major extrinsic (entorhinal) afferents that normally terminate on peripheral granule cell dendrites causes retraction of these dendrites. At the same time, there is growth of paroximal dendritic portions. Proximal dendrites are targets of associational fibers, which are known to sprout under these culture conditions. © 1994 Wiley‐Liss, Inc.
Primate striatonigral projections: A comparison of the sensorimotor‐related striatum and the ventral striatum
Authors: Lynd‐Balta E. , Haber S. N. 
Published: January 2005

AbstractThe striatum receives topographic cortical inputs with the limbic lobe terminating in the ventral striatum and sensorimotor cortical regions terminating in the dorsolateral striatum. The organization of striatonigral projections originating from these different striatal territories was examined in primate by using several anterograde tracers.The ventral striatum innervates a large area of the substantia nigra, including the medial pars reticulata and much of the pars compacta. Moreover, projections from separate areas of the ventral striatum overlap considerably in the substantia nigra. No mediolateral or rostrocaudal topographic order is apparent, and the area of the substantia nigra associated with the ventral striatum is extensive. In contrast, the sensorimotor‐related striatum innervates a limited region of the ventrolateral substantia nigra. Similar to ventral striatonigral projections, projections originating from different areas of the sensorimotor‐related striatum send converging inputs to the substantia nigra. Sensorimotor‐related striatonigral projections avoid the region of the dopaminergic neurons in the dorsal pars compacta. Striatonigral projections from the sensorimotor‐related and ventral striatum do not overlap in the substantia nigra. Examination of the outputs of discrete striatal loci indicates that the organization of striatonigral projections is more related to corticostriatal inputs than to a simple rostrocaudal, dorsoventral, or mediolateral tpography of the striatum.Striatal projections that originate from different striatal territories are distinct and nonoverlapping, thus supporting the concept of segregated striatonigral circuits. However, areas of the striatum that receive common cortical inputs send converging inputs to the substantia nigra. This suggests that the substantia nigra is also an important link for integrating information between functionally related (sub)circuits. © 1994 Wiley‐Liss, Inc.
The development of GABA immunoreactivity in the retina of the zebrafish (brachydanio rerio)
Authors: Sandell Julie H. , Martin Stella C. , Heinrich Gerhard 
Published: January 2005

AbstractThe goal of this study was to determine the pattern of gamma‐aminobutyric acid (GABA) expression in the retina and optic nerve of the zebrafish (Brachydanio rerio) during embryonic development. Zebrafish embryos were fixed at intervals between 1 and 4 days postfertilization, and semithin plastic sections were prepared for postembedding immunocytochemistry with antisera, against GABA. Sections were also prepared from several adult zebrafish eyes for comparison. GABA immunoreactivity first appeared in the optic nerve at 2 days postfertilization, and by 2.5 days the inner nuclear layer (INL), inner plexiform layer (IPL), retinal ganglion cell layer, and optic nerve were all positive for GABA. The GABA expression in the retinal ganglion cell layer and optic nerve was transient, however, and these structures were largely unlabeled by 4 days postfertilization. The pattern of GABA immunoreactivity at 4 days resembled that seen in the adult zebrafish: A large population of presumptive amacrine cells was labeled at the base of the INL, and the IPL was positive for GABA, as were occasional cells in the ganglion cell layer. Horizontal cells, particularly at the retinal margins, were also GABA positive beginning at about 3 days postfertilization. The transient expression of GABA in retinal ganglion cells and their axons during the period when synaptic contacts are being established both within the retina and between the retina and central targets suggests that GABA may have a role in the development of this system, in addition to serving as a classical neurotransmitter. © 1994 Wiley‐Liss, Inc.
Proctolin and excitation of the crayfish swimmeret system
Authors: Acevedo Larisa D. , Hall Wendy M. , Mulloney Brian 
Published: January 2005

AbstractThe ventral nerve cord of crayfish contains axons of five pairs of excitatory interneurons, each of which can activate the swimmeret system. Perfusion of the ventral nerve cord with the neuropeptide proctolin also activates the swimmeret system. The experiments reported here were conducted to test the hypothesis that one or more of these excitatory interneurons uses proctolin as a transmitter.Each of the five excitatory axons was located and stimulated separately in an individual crayfish, and similar motor activity was elicited by stimulating each of them. Quantitative comparison of spontaneous swimmeret motor patterns with activity caused by stimulating one of these excitatory axons, EC, or by perfusing with proctolin solutions showed that the motor patterns produced under these three conditions were not significantly different (P > 0.05).By using a new, affinity‐purified proctolin antiserum, we labeled axons in the connective tissue between the last thoracic and first abdominal ganglion and compared the positions of labeled axons with the previously described positions of the excitatory axons. About 0.3% of the axons in these connective tissues showed proctolin‐like immunoreactivity, but heavily labeled pairs of axons did occur bilaterally in the regions of excitatory swimmeret axons. The projections of these labeled axons into the abdominal ganglia were traced in serial plastic sections. Labeled processes were abundant in the lateral neuropils, the loci of the swimmeret pattern‐generating circuitry.From this evidence, we propose that three of these excitatory swimmeret interneurons use proctolin as a transmitter, but that a fourth does not. The evidence for the fifth axon is ambiguous. © 1994 Wiley‐Liss, Inc.
Single retinal ganglion cells projecting in bilaterally to the lateral geniculate nuclei or superior colliculi by way of axon collaterals in the cat
Authors: Kondo Yasuko , Takada Masahiko , Tokuno Hironobu , Mizuno Noboru 
Published: January 2005

AbstractIn most mammals with frontalized eyes, retinal ganglion cells in the nasal or temporal retina send their axons to the contralateral or ipsilateral half, respectively, of the brain. Previous studies in the cat, however, have indicated a retinal region of “nasotemporal overlap” from which arise the retinal projections to both the contralateral and ipsilateral halves of the brain. The present study thus examined in the cat whether any retinal ganglion cells give rise to bifurcating axons that innervate both halves of the brain.By employing fluorescent retrograde double labeling, we investigated whether or not single retinal ganglion cells project bilaterally to the lateral geniculate nuclei or superior colliculi by way of axon collaterals. After Fast Blue was injected into the lateral geniculate nucleus on one side and Diamidino Yellow was injected contralaterally into the lateral geniculate nucleus, 100–200 ganglion cells in each retina were double labeled with both tracers. These double‐labeled cells were distributed primarily in the temporal retina, including the region around the vertical meridian and, additionally, in the nasal retina. About 60–80% of the double‐labeled cells had large cell bodies (more than 25 μm in diameter), and the others had medium‐sized ones (15–25 μm in diameter). The pattern of distribution of double‐labeled cells, which was observed after the combined injection into both superior colliculi, was similar to that seen after the combined injection into both lateral geniculate nuclei; more than 9% of double‐labeled cells, however, were large.The results indicate that a certain population of ganglion cells in the cat retina send their axons bilaterally to the lateral geniculate nuclei or superior colliculi by way of axon collaterals. The bilaterally projecting ganglion cells are mostly large, corresponding probably to α cells (the morphological counterparts of Y cells). In comparison with the patterns of bilateral projections of single retinal ganglion cells in the rat and monkey, the pattern of the bilateral retinofugal projections in the cat could represent an intermediate between those in the rat and monkey. © 1994 Wiley‐Liss, Inc.