bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gonadal steroids regulate immunoreactive tachykinin in the ventromedial nucleus of the rat hypothalamus
Authors: Akesson Thomas R. 
Published: January 2005

AbstractThe ventromedial nucleus of the hypothalamus (VMH) is an important site in the mediation of female receptive behavior (lordosis); however, the sequence of events that eventually facilitate this estrogen‐dependent behavior is only partially understood. Here, evidence is presented, suggesting that an interaction between gonadal steroids and tachykinin peptides is involved. Tachykinin‐immunoreactive (TACir) neurons were distributed throughout the anterior (VMHa), dorsomedial (VMHdm), central (VMHc), and ventrolateral (VMHvl) subdivisions in the adult male and female rat. Numbers of cells in the VMH of intact males and males that had been castrated for three weeks were similar. Among females, numbers of TACir cells in the VMHvl were significantly increased over numbers seen in ovariectomized females by a two day (1.5X) and by a two week (1.6X) exposure to estrogen. In the VMHa, numbers of TACir cells were also significantly higher in females that received replacement estrogen compared to ovariectomized females. Since estrogen concentration by TACir neurons is common in the VMHvl and rare in the VMHa, estrogen may have both direct and indirect effects on tachykinin synthesis. In the caudal pole of the VMH, staining intensity of TACir fibers varied with endocrine state. In intact males, castrated males, and ovariectomized females, fibers were lightly stained. In females exposed to estrogen for two days, fibers were moderately intense, and in females exposed to estrogen for two weeks, they formed a darkly stained plexus. These responses to estrogen suggest that production of tachykinin peptides in the VMH is involved in facilitation of female typical sexual behavior.
Reevaluation of area 3b in the cat based on architectonic and electrophysiological studies: Regional variability with functional and anatomical consistencies
Authors: Leclerc S. S. , Avendaño C. , Dykes R. W. , Waters R. S. , Salimi I. 
Published: January 2005

AbstractMost anatomical and electrophysiological studies of the cat primary somatosensory cortex rely on Hassler and Muhs‐Clement's (J. Hirnforsch. 6:377‐420, 1964) cyto‐ and myeloarchitectonic description distinguishing area 3a from area 3b; however, discrepancies in the delineation of these areas in published studies suggest that many workers have found it difficult to apply those criteria systematically. We examined the cytoarchitecture of area 3b in Nissl stained sagittal sections from which electrophysiological data had been obtained prior to sacrifice. Rostrocaudal rows of electrode penetrations placed at different mediolateral positions in the gyrus located regions responsive to stimulation of either cutaneous or deep structures. Small electrolytic lesions allowed these data to be related to the cytoarchitecture. A systematic study throughout the trunk and limb representations found cutaneous responses in cortical regions characterized by a thick and cell‐dense granular layer IV, however these same regions had a variable population of medium‐sized and/or large pyramidal cells in layer V. Pyramidal cells were practically absent from the forelimb representation, but were present to varying degrees in the trunk and hindlimb representations. Moreover, the relative thickness and cell‐density in layer IV were greater in the forelimb than in the hindlimb representations. Deep responses were found in cortex characterized by a thinner layer IV. Since the characteristics of layer V in area 3a were variable, it was less useful for identification of the border between areas 3a and 3b. Clear changes in the intensity and laminar distribution of acetylcholinesterase staining occurred between areas 3a and 3b, making this a useful adjunct to the Nissl stain.
Birthdates of neurons in the retinal ganglion cell layer of the ferret
Authors: Reese B. E. , Thompson W. F. , Peduzzi J. D. 
Published: January 2005

AbstractThe present study determined the temporal and spatial patterns of genesis for neurons of different sizes in the retinal ganglion cell layer of the ferret. Fetal ferrets were exposed to tritiated thymidine on embryonic days E‐22 through E‐36. One to 3 months after birth, they were perfused and their retinae dissected, and autoradiographs were prepared from resinembedded sections throughout the entire flattened retinal ganglion cell layer. Soma size differences in conjunction with separate retrograde labeling and calbindin immunocytochemical studies were used as criteria for identifying different retinal ganglion cell subtypes in juvenile and adult ferrets.Neurons of different sizes in the ganglion cell layer were generated at different stages during development. Medium sized cells were generated primarily between E‐22 and E‐26; the largest cells were generated between E‐24 and E‐29; small cells were generated between E‐26 and E‐32; and very small cells were generated between E‐29 and E‐36. The former three groups were interpreted to be three subtypes of retinal ganglion cells, while the latter group was interpreted to be displaced amacrine cells.This temporal order of the genesis of ganglion cell classes is consistent with the spatial ordering of their fibers in the mature optic chiasm and tract, and it is consistent with the developmental change in decussation pattern recently shown in the optic pathway of embryonic ferrets. The spatial pattern of genesis suggests that ganglion cells of a particular class are added to the ganglion cell layer in a centroperipheral fashion initiated in the dorsocentral retina nasal to the area centralis. No evidence was found for a wave of ganglion cell addition that proceeded in a spiralling pattern around the area centralis, as has been reported in the cat.
Organization of cortical afferents to the rostral, limbic sector of the rat thalamic reticular nucleus
Authors: Lozsádi D. A. 
Published: January 2005

AbstractThe organization of limbic cortical afferents to the thalamic reticular nucleus (TRN) is described. Wheat germ agglutinin conjugated to horseradish peroxidase (WGA‐HRP), biocytin, neurobiotin, or fluorescent dextrans was delivered into the rat cingulate, retrosplenial, and, for comparison, somatosensory cortices, In other species a slab‐like arrengement of cortical terminals has been described for sensory TRN sectors. Here this is seen in the rat somatosen‐sory sector. Terminals from limbic cortices did not cluster into slabs but were found to fill the entire thickness of distinct rostral TRN regions. The cingulate and retrosplenial recipient TRN regions overlap, as do the projections from these cortical areas to anterior thalamic nuclei. Retrosplenial fibres contacted the dorsal and rostral TRN, which is be connected to the retrosplenial‐recipient anteroventral, anterodorsal, and laterodorsal thalamic nucler. Cingulate terminals occupied more ventral regions of the rostral TRN. This area is connected to thalamic nuclei also innervated by the cingulate cortex: the mediodorsal and anteromedial nuclei. A loose, but clear, topography could be defined for the cingulate‐reticular pathway: rostrocaudal and mediolateral directions in the cortex are represented by ventrodorsal and rostrocaudal directions in the TRN, respectively. This organization of limbic corticoreticular pathway corresponds to the arrangement of limbic corticothalamic connections. The ultrastruc‐ture of the limbic cortical axon terminals was similar to that of the cortical boutons (D‐type) described previously. The labelled terminals formed asymmetrical synapses onto dendritic profiles of reticular neurons. These findings, together with data in the literature, show significant morphological and connectional differences within the TRN that imply functional heterogeneities.
Quantitative analyses of neuroepithelial cell shapes during bending of the mouse neural plate
Authors: Smith Jodi L. , Schoenwolf Gary C. , Quan Jan 
Published: January 2005

AbstractDespite a wealth of information about cell behaviors contributing to neurulation in chick embryos, similar behaviors in mouse embryos have yet to be well characterized. This study examines cell behaviors occurring during bending of the mouse neural plate, in particular, qualitative and quantitative changes in neuroepithelial cell shape. Our current results demonstrate that in mouse embryos (1) the median hinge point (MHP), a localized region of neural plate that becomes anchored to the underlying prechordal plate mesoderm or notochord/ notochordal plate and forms a midline longitudinal furrow around which folding of the remaining neural plate (i.e., the part of the neural plate not involved in MHP formation) occurs, develops during stages of neural fold elevation; (2) the MHP is enriched with wedge‐shaped neuroepithelial cells but has significantly fewer spindle‐shaped, inverted wedge‐shaped, and globular neuroepithelial cells than do the adjacent paired lateral areas of the neuroepithelium (L); and (3) each L is enriched with spindle‐shaped, inverted wedge‐shaped, and globular neuroepithelial cells but has significantly fewer wedge‐shaped neuroepithelial cells than does the MHP. Thus wedging of neuroepithelial cells occurs during bending of the mouse neural plate and is localized to the MHP during neural fold elevation. Similarly, previous studies in the chick have shown that neuroepithelial cells become wedge shaped during bending of the neural plate and that such cell wedging is localized to the MHP during neural fold elevation. Such studies also have shed light on the roles of MHP formation and localized wedging of neuroepithelial cells within the MHP in the chick; however, such roles have yet to be elucidated in the mouse. It is probable that the MHP in mouse embryos, like that in chick embryos, provides a locus for bending of the neural plate and that wedging of neuroepithelial cells within the MHP provides the force necessary to generate the longitudinal midline furrow around which subsequent folding of the neural plate (i.e., neural fold elevation) occurs. Further studies are necessary to define these roles more precisely. © 1994 Wiley‐Liss, Inc.
Distribution of VIP mRNA and two distinct VIP binding sites in the developing rat brain: Relation to ontogenic events
Authors: Hill Joanna M. , Agoston Denes V. , Gressens Pierre , McCune Susan K. 
Published: January 2005

AbstractThe peptide neurotransmitter vasoactive intestinal peptide (VIP) has neurotrophic properties and influences neurobehavioral development. To assess the role of VIP during neural ontogeny, the present work traces the development of VIP mRNA with in situ hybridization and VIP receptors with in vitro autoradiography in rat central nervous system (CNS) from embryonic day 14 (E14) to the adult.VIP mRNA was not evident in the CNS until birth. Postnatally, it was expressed in several distinct brain regions, but its distribution bore little relation to that of VIP receptors.VIP receptors were present and expressed changing patterns of distribution throughout CNS development. The changing patterns were the result of (1) the transient appearance of GTP‐insensitive VIP receptors in several regions undergoing mitosis or glial fasciculation and (2) the transient appearance of GTP‐sensitive VIP receptors homogeneously distributed throughout the CNS during the first 2 postnatal weeks, the period of the brain growth spurt. At E14‐16 VIP binding was dense throughout the brainstem and spinal cord, but limited in the rest of the brain. From E19 to postnatal day 14 (P14), while VIP binding was higher in germinal zones, it tended to be uniformly dense throughout the remainder of the brain. By P21 the adult pattern began to emerge; VIP binding was unevenly distributed and was related to specific cytoarchitectural sites.Since the expression of VIP in the CNS is limited to postnatal development but VIP receptors are abundant prenatally, we suggest that extraembryonic VIP may act upon prenatal VIP receptors to regulate ontogenic events in the brain. © 1994 Wiley‐Liss, Inc.
Direct projections from the entopeduncular nucleus to the lower brainstem in the rat
Authors: Takada Masahiko , Tokuno Hironobu , Ikai Yoshiaki , Mizuno Noboru 
Published: January 2005

AbstractThe present study reports the existence of projection fibers from the entopeduncular nucleus to the superior colliculus and lateral parts of the pontobulbar tegmental regions (so‐called lateral tegmental field) in the rat, suggesting that the entopeduncular nucleus may control eye‐head and orofacial movements via these projection fibers. The anterograde axonal tracing with Phaseolus vulgaris‐leucoagglutinin has revealed that the entopedunculotectal fibers terminate, bilaterally, with an ipsilateral predominance, in the deep layers of the superior colliculus through its rostral one‐third level and that the entopedunculotegmental fibers terminate, bilaterally, with an ipsilateral predominance, in the parabrachial area, reticular formation surrounding the trigeminal motor nucleus, and parvicellular, dorsal, and ventral reticular nuclei. The cells of origin of the entopedunculotectal and entopedunculotegmental projections have been identified by retrograde axonal tracing with Fluoro‐Gold and cholera toxin B subunit. The entopedunculotectal or entopedunculotegmental fibers originate, respectively, from the dorsal or ventral part of the entopeduncular nucleus. Additionally, a series of fluorescent retrograde double‐labeling experiments with Fast Blue and Diamidino Yellow have indicated that single entopeduncular nucleus neurons projecting to the superior colliculus or lateral tegmental field often send their axon collaterals to the lateral habenular nucleus.The entopedunculotectal fibers are assumed to control head movements, which may be provoked via the tectospinal fibers, and further to participate in eye movements as the nigrotectal fibers that have been known to arise from the substantia nigra pars reticulata to end in the deep layers of the superior colliculus primarily through its caudal two‐thirds level. The entopedunculotegmental fibers are presumed to be involved in control of orofacial movements, because the sites of termination of the entopedunculotegmental fibers correspond well with the reported areas of distribution of premotor interneurons for the trigeminal motor, facial, and hypoglossal nuclei. © 1994 Wiley‐Liss, Inc.
Correlation of local changes in cerebral blood flow, capillary density, and cytochrome oxidase during development
Authors: Tuor U. I. , Kurpita G. , Simone C. 
Published: January 2005

AbstractAlthough elevations in cerebral metabolic demand during development may induce angiogenesis, the correlation among ontogenic changes in local cerebral blood flow, cytochrome oxidase activity (an index of oxidative capacity) and capillary density have not been examined previously. We measured these parameters in selected regions of the brains of anesthetized rabbits of various ages. Increases in all three parameters occurred postnatally within the cerebral cortex and striatum, whereas in the medulla, values at birth were similar to those in adults. In newborns, the pattern of distribution of blood flow within the parietal cortex was such that levels were maximal in the outer layers and declined in deeper layers. This distribution correlated closely with that of capillary density, whereas cytochrome oxidase activity was maximal at levels deeper in the cortex. By postnatal day 17, the distribution for all three parameters was similar to that of cytochrome oxidase activity in young animals. A regression analysis of the regional values demonstrated a positive correlation between capillary density and blood flow in young (≤ postnatal day 8) and old (≥ postnatal day 17) animals. In contrast, cytochrome oxidase activity and capillary density were poorly correlated in young animals but positively correlated in older animals, with the slopes being markedly different (P < 0.005). The results suggest that early in postnatal development, the pattern of cytochrome oxidase activity is relatively mature compared with that of capillary density. By postnatal day 17, microvascular anatomy is closely associated to oxidative capacity, likely reflecting a steady state regulation of capillary density to metabolic requirements. © 1994 Wiley‐Liss, Inc.
Distribution of choline acetyltransferase immunoreactivity in the pigeon brain
Authors: Medina Loreta , Reiner Anton 
Published: January 2005

AbstractWe have investigated the distribution of cholinergic perikarya and fibers in the brain of the pigeon (Columba livia). With this aim, pigeon brain sections were processed immunohistochemi‐cally by using an antiserum specific for chicken choline acetyltransferase. Our results show cholinergic neurons in the pigeon basal telencephalon, the hypothalamus, the habenula, the pretectum, the midbrain tectum, the dorsal isthmus, the isthmic tegmentum, and the cranial nerve motor nuclei. Cholinergic fibers were prominent in the dorsal telencephalon, the striatum, the thalamus, the tectum, and the interpeduncular nucleus. Comparison of our results with previous studies in birds suggests some major cholinergic pathways in the avian brain and clarifies the possible origin of the cholinergic innervation of some parts of the avian brain. In addition, comparison of our results in birds with those in other vertebrate species shows that the organization of the cholinergic systems in many regions of the avian brain (such as the basal forebrain, the epithalamus, the isthmus, and the hindbrain) is much like that in reptiles and mammals. In contrast, however, birds appear largely to lack intrinsic cholinergic neurons in the dorsal (“neocortex‐like”) parts of the telencephalon. © 1994 Wiley‐Liss, Inc.
Dendritic architecture of hypoglossal motoneurons projecting to extrinsic tongue musculature in the rat
Authors: Altschuler Steven M. , Bao Xinmin , Miselis Richard R. 
Published: January 2005

AbstractThe tracer, cholera toxin‐horseradish peroxidase, was used to determine the dendritic architecture and organization of hypoglossal motoneurons in the rat. In 22 animals, the tracer was injected unilaterally into either the geniohyoid, genioglossus, hyoglossus, or styloglossus muscle. Within the hypoglossal nucleus, motoneurons innervating the extrinsic tongue muscles were functionally organized. Geniohyoid and genioglossus motoneurons were located within the ventrolateral and ventromedial subnuclei, respectively, while hyoglossus and styloglossus motoneurons were located within the dorsal subnucleus.Motoneurons located in all subnuclear divisions were found to have extensive dendrites that extended laterally into the adjacent reticular formation and medially to the ependyma. Less extensive extranuclear dendritic projections were found in the dorsal vagal complex and median raphe. Prominent rostrocaudal and mediolateral dendritic bundling was evident within the ventral subnuclei and dorsal subnucleus, respectively. Dendritic projections were also found extending inter‐ and intrasubnuclearly with a distinct pattern for each muscle.These data suggest that the varied and extensive dendritic arborizations of hypoglossal motoneurons provide the potential for a wide range of afferent contacts for, and interactions among, motoneurons that could contribute to the modulation of their activity. Specifically, the prominent dendritic bundling may provide an anatomic substrate whereby motoneurons innervating a specific muscle receive and integrate similar afferent input and are thus modulated as a functional unit. In contrast, the extensive intermingling of both inter‐ and intrasubnuclear dendrites within the hypoglossal nucleus may provide a mechanism for the coordination of different muscles, acting synergistically or antagonistically to produce a tongue movement. © 1994 Wiley‐Liss, Inc.
Intrinsic cortical connections in macaque visual area V2: Evidence for interaction between different functional streams
Authors: Levitt Jonathan B. , Yoshioka Takashi , Lund Jennifer S. 
Published: January 2005

AbstractArea V2 of macaque visual cortex represents an important but poorly understood stage in visual processing. To provide a better understanding of the region, we studied the organization of its intrinsic cortical connections by making focal (200–300 μm) iontophoretic microinjections of the tracer biocytin. Alternate tissue sections were tested for biocytin, cytochrome oxidase (CO), or Cat‐301 immunoreactivity to localize biocytin label relative to the three stripelike compartments that characterize this area. Biocytin‐labeled pyramidal neurons of layers 2/3, and, to a lesser extent, layer 5, provided laterally spreading axon projections that terminated in discrete patches (250–300 μm diameter), primarily in layers 1–3. Any injected locus in V2 projected to 10–15 similarly sized patches, up to 4 mm from the injection site, and distributed in an elongated field orthogonal to the stripe compartments. We noted prominent patchy connections within, as well as between, individual compartments, perhaps reflecting functional substructures within stripes. Each stripe compartment projected to all three compartments but with different relative frequencies; CO‐rich compartments projected mainly to other CO‐rich compartments (75%), whereas CO‐poor compartments projected equally to CO‐rich and CO‐poor compartments. We therefore emphasize the existence of substantial interconnections among all three V2 compartments. As further evidence for crosstalk between visual channels, we also noted an input to the V2 “thick” CO stripes from V1 cells in layer 4A as a distinct population in addition to the neurons of layer 4B. Thus, the CO stripe architecture may not be a marker for strictly segregated parallel visual pathways through V2. © 1994 Wiley‐Liss, Inc.