bluuebunny/crossref_metadata_2025_split huggingface dataset:
Developmental changes in layer I of the human neocortex during prenatal life: A DiI‐tracing and AChE and NADPH‐d histochemistry study
Authors: Meyer Gundela , González‐Hernández Tomás 
Published: January 2005

AbstractThe development of fetal layer I (marginal zone, MZ) was studied in the human neocortex by using DiI tracing and AChE and NADPH‐d histochemistry, and examining the Nissl‐stained material of the Yakovlev Collection. We describe the sequential maturation of the Cajal‐Retzius (CR) cells and the granule cells of the subpial granular layer (SGL), and the close relationship between both. The first CR cells appear in the primordial plexiform layer, at 6 gestational weeks (GW). After the formation of the cortical plate, they settle under the pial surface. At 13 GW, the SGL begins to form around the CR cells. The horizontal members of a polymorphic population of CR cells begin to mature at 13 GW, and the intermediate and vertical forms differentiate at 16 and 18 GW, respectively. All CR cells project into an axonal plexus in the lower third of the MZ. From 18 GW, CR cells and SGL become segregated, and the polymorphic CR cells lie now below the SGL, with which they remain connected by ascending processes. Granule cells invade the lower MZ contacting somata and processes of CR cells. The somata of vertical CR cells elongate until 23/24 GW when they show degenerative signs. After 24 GW, all polymorphic CR cells die. Granule cells degenerate after 24 GW; the SGL disappears at 28/30 GW. A population of persisting CR cells, morphologically different from the transient polymorphic forms, appears in a subpial position and survives in small numbers throughout life. Small non‐CR neurons differentiate first in the lower half of layer I, thereafter also in the upper half. Histochemically, all CR cells are AChE‐positive; they contain NADPH‐d only transiently at 20 GW. We propose that CR cells and SGL provide a transient innervation network for the developing cortical plate at a time when the definitive fiber systems of the molecular layer are not yet established. © 1993 Wiley‐Liss, Inc.
Ontogeny of GABAA receptor subunit mRNAs in rat spinal cord and dorsal root ganglia
Authors: Ma Wu , Saunders Paul A. , Somogyi Roland , Poulter Michael O. , Barker Jeffery L. 
Published: January 2005

AbstractRelatively little is known about the development of GABAA receptor subunits and their gene expression in mammalian spinal cord. The expressions of mRNAs encoding 13 GABAA receptor subunits (α1–6, β1–3, γ1–3, and δ) in embryonic, postnatal, and adult rat spinal cord and dorsal root ganglia (DRG) cells were studied by in situ hybridization and reverse transcription‐polymerase chain reaction (RT ‐ PCR) analysis. Both techniques revealed the presence of all subunit mRNAs originally found in the rat brain, except for α6, which was not detectable, and δ, which was weakly detected only by RT‐PCR. Two anatomically distinctive sets of subunit mRNAs were found by in situ hybridization within the ventricular zone (VZ) and mantle zone (MZ). The trio of α4, β1, and γ1 subunit mRNAs emerged exclusively in neuroepithelial cells at embryonic day 13 (E13) and remained detectable in the VZ until E17. In the MZ, β3 subunit mRNA was first detected at E12, while α2, α3, α5, β2, γ2, and γ3 transcripts appeared at E13. Expressions of the subunit mRNAs in the MZ rapidly increased and expanded in a ventrodorsal sequence from motoneurons to dorsal horn neurons before reaching a peak in the late embryonic/early postnatal period. The mRNA expressions declined during postnatal development, by region‐selective depletion, with α4, α5, β1, β2, γ1, and γ3 subunit mRNAs becoming barely detectable. In contrast, α2, α3, β3, and γ2 transcripts persisted into adulthood with distinct anatomical distributions. RT‐PCR analysis revealed unique developmental patterns in the intensities of PCR products, most of which were in good agreement with developmental changes in the densities of hybridized mRNA signals. However, RT‐PCR amplified minute amounts of mRNAs for α1, α4, α5, β1, β2, γ1, γ3, and δ subunits in adults, which were not found in film autoradiograms, but could be detected in a few grain‐positive cells in emulsion‐dipped sections. DRG cells expressed α2, α3, α5, β2, β3, and γ2 subunit mRNAs during embryogenesis but only α2, β3, and γ2 subunit mRNAs were reliably detected in the adult. The transient expression of α4β1γ1 subunit mRNAs primarily in the VZ correlates with the period of neurogenesis, while the developmental changes of α2, α3, β3, and γ2 subunit mRNAs in the MZ parallels previously reported changes in GABA expression and in synapse formation and elimination. These results implicate a role of early‐expressed GABA and GABAA receptors in the development of rat spinal cord. © 1993 Wiley‐Liss, Inc.
Distinct distributions of five N‐methyl‐D‐aspartate receptor channel subunit mRNAs in the forebrain
Authors: Watanabe Masahiko , Inoue Y. , Sakimura K. , Mishina M. 
Published: January 2005

AbstractThe distributions of five NMDA receptor channel subunit mRNAs in the mouse forebrain at postnatal day 21 were semiquantitatively examined by in situ hybridization with subunit‐specific oligonucleotide probes. In contrast to ubiquitous distribution of the ζ1 subunit mRNA throughout the forebrain, distributions of four ϵ subunit mRNAs were highly variable from nucleus to nucleus. The telencephalon (except for the septum) expressed the ϵ1 and ϵ2 subunit mRNAs. Various combinations of the ϵ1, ϵ2, ϵ3, and ϵ4 subunit mRNAs were present in different nuclei of the septum, the olfactory bulb, and the thalamus. In the hypothalamus, the suprachiasmatic nucleus expressed distinct signals for the ϵ3 subunit mRNA alone, whereas other nuclei showed faint signals for the ϵ1, ϵ2, and ϵ4 subunit mRNAs. Moreover, different signal levels of the ϵ subunit mRNAs were found in various regions. The hippocampal CA1 region expressed higher signals for the ϵ1 and ϵ2 subunit mRNAs than the CA3 region and the dentate gyrus. In the cerebral cortex, signal levels of the ϵ1 subunit mRNA were higher in the laminae II/III, IV, and VI than the lamina V, whereas those of the ϵ2 subunit mRNA were highest in laminae II/III and lowest in laminae IV and V. Different signal levels between the ϵ1 and ϵ2 subunit mRNAs were also discerned in the amygdala, the caudate‐putamen, and the thalamus. The distinct anatomical distributions and differential signal levels of the ϵ subunit mRNAs strongly suggest different subunit organizations of the NMDA receptor channel in different forebrain neurons, which may result in functional diversity of the channel in vivo. © 1993 Wiley‐Liss, Inc.
Capacity of the retinogeniculate pathway to reorganize following ablation of visual cortical areas in developing and mature cats
Authors: Lomber Stephen G. , Payne Bertram R. , Cornwell Paul , Pearson Helen E. 
Published: January 2005

AbstractThe purpose of the present study was to determine the pattern and density of retinal projections to the dorsal lateral geniculate nucleus (dLGN) following ablation of visual cortical areas in developing cats of different postnatal ages and in mature cats. The terminations of retinal projections to the dLGN were evaluated following the injection of tritiated amino acids into one eye. Regardless of age, a visual cortical ablation of areas 17 and 18 induces massive death of neurons within the regions of the dLGN that are linked topographically to the cortical areas removed. However, the pattern of retinal projections to these degenerated regions of the dLGN differs depending upon whether the cortical lesion is incurred early in postnatal life or in adulthood. Following ablation on the day of birth (P1), virtually all surviving cells were found in the C‐complex of dLGN with only a token number in the A‐laminae. Correspondingly, retinal projections were maintained to the C‐complex of the nucleus and were barely detectable in the degenerated A‐laminae. However, in cats in which areas 17 and 18 had been removed in adulthood (≥ 6 months of age) retinal projections were maintained to the A‐laminae even though nearly all neurons in those laminae had degenerated. Moreover, a subgroup of animals that incurred area 17 and 18 ablations at P1 showed that the modification of retinal projections to the A‐laminae occurs within the first postnatal month, and an additional subgroup showed that retinal projections become increasingly resistant to the degenerative events in the dLGN that follow ablation of areas 17 and 18 at progressively older ages during the first postnatal month. Furthermore, retinal inputs also respond, in an age‐dependent way, to degeneration of neurous in the C‐complex induced by extension of the cortical ablation to include extrastriate visua areas. © 1993 Wiley‐Liss, Inc.
Distribution and neurochemical phenotypes of caudal medullary neurons activated to express cFos following peripheral administration of cholecystokinin
Authors: Rinaman Linda , Verbalis J. G. , Stricker E. M. , Hoffman G. E. 
Published: January 2005

AbstractImmunocytochemical localization of the protein product of the proto‐oncogene C‐fos allows anatomical identification of physiologically activated neurons. The present study examined the subnuclear distribution of cFos protein in the rat caudal medulla following peripheral administration of cholecystokinin octapeptide, which reduces feeding and gastric motility by a vagally mediated mechanism. To begin phenotypic characterization of neurons activated to express cFos following cholecystokinin treatment, double‐labeling techniques were used to identify vagal motor neurons and neurons immunoreactive for tyrosine hydroxylase, neuropeptide Y, and neurotensin. Activated cells were most prevalent in the subnucleus medialis of the nucleus of the solitary tract, less prevalent in the subnucleus commissuralis, and virtually absent in the subnuclei centralis and gelatinosus. Many activated cells occupied the caudal area postrema; some of these were catecholaminergic. In contrast, activated cells were sparse within the medial rostral area postrema. Other activated cells occupied the dorso‐ and ventrolateral medulla and the midline raphe nuclei. Retrograde labeling of vagal motor neurons confirmed that very few were activated. Those that were activated occupied the caudal dorsal motor nucleus. In the dorsomedial medulla, 51% of catecholaminergic neurons and 39% of neurons positive for neuropeptide Y were activated, but no neurotensin‐positive neurons were activated. In the ventrolateral medulla, 25% of catecholaminergic neurons and 27% of neuropeptide Y‐positive neurons were activated. By characterizing the subnuclear distribution and chemical phenotypes of neurons activated by exogenous cholecystokinin, these data contribute to elucidation of the neural circuits mediating the behavioral, physiological, and neuroendocrine effects produced by this peptide. © 1993 Wiley‐Liss, Inc.
Organization of the cerebral ganglion of the colonial ascidian Polyandrocarpa misakiensis
Authors: Koyama Hiromichi , Kusunoki Toyokazu 
Published: January 2005

AbstractThe cerebral ganglion of a budding styelid ascidian, Polyandrocarpa misakiensis, whose phylogenetic location is midway between vertebrates and invertebrates, was studied by light and electron microscopy to obtain some insight into the evolution of the central nervous system. The lateral and ventral sides of the ganglion are surrounded by blood sinuses. The ganglion is covered with a thin fibrous sheath through which many nerve fibers run. The ganglion is composed of a cellular cortex and a fibrous medulla. The cortex consists of three to six layers of large and small neurons. Some neurons are also scattered within the medulla. Many neurons are monopolar, and some are bi‐ or multipolar. The cytoplasm of the large neurons is dense with extensive rough endoplasmic reticulum, free ribosomes, mitochondria, one or more Golgi complexes, large dense bodies, and many clear or dense vesicular structures. Some neurons send their processes directly into the lumen of the sinuses. The medulla is composed of loosely arranged nerve fibers without cellular wrappings. The medullary fibers contain vesicles and granules of various sizes, and microtubules. At the anterior and posterior ends of the ganglion, the medullary fibers are assembled into thick peripheral nerve fiber bundles. The peripheral nerve fibers are enveloped and subdivided by fibrous structures. Synapses are found in the medulla, in the cortex, and between the peripheral nerve fibers. The presence of neurons and axodendritic or axoaxonic synapses in the peripheral nerve fibers is consistent with a diffuse organization of the central nervous system of the ascidians. The morphology of the central nervous system synapses is comparable to that of other invertebrates, but the locations of the synapses are similar to those of vertebrates. © 1993 Wiley‐Liss, Inc.
Motoneuron morphology in the dorsolateral nucleus of the rat spinal cord: Normal development and androgenic regulation
Authors: Goldstein L. A. , Sengelaub D. R. 
Published: January 2005

AbstractThe rat lumbar spinal cord contains two sexually dimorphic motor nuclei, the spinal nucleus of the bulbocavernosus (SNB), and the dorsolateral nucleus (DLN). These motor nuclei innervate anatomically distinct perineal muscles that are involved in functionally distinct copulatory reflexes. The motoneurons in the SNB and DLN have different dendritic morphologies. The dendrites of motoneurons in the medially positioned SNB have a radial, overlapping arrangement, whereas the dendrites of the laterally positioned DLN have a bipolar and strictly unilateral organization. During development, SNB motoneuron dendrites grow exuberantly and then retract to their mature lengths. In this experiment we determined whether the adult difference in SNB and DLN motoneuron morphology was reflected in different patterns of dendritic growth during normal development. Furthermore, the development of both these nuclei is under androgenic control. In the absence of androgens, SNB dendrites fail to grow; testosterone replacement supports normal dendritic growth. Thus, we also examined the development of DLN dendrites for similar evidence of androgenic regulation.By using cholera toxin‐horseradish peroxidase (BHRP) to label motoneurons retrogradely, we measured the morphology of DLN motoneurons in normal males, and in castrates treated with testosterone or oil/blank implants at postnatal day (P) 7, P28, P49, and P70. Our results demonstrate that in contrast to the biphasic pattern of dendritic development in the SNB, dendritic growth in the DLN was monotonic; the dendritic length of motoneurons increased more than 500% between P7 and P70. However, as in the SNB, development of DLN motoneuron morphology is androgen‐dependent. In castrates treated with oil/blank implants, DLN somal and dendritic growth were greatly attenuated compared to those of normal or testosterone‐treated males. Thus, while androgens are clearly necessary for the growth of motoneurons in both the SNB and DLN, their different developmental patterns suggest that other factors must be involved in regulating this growth. © 1993 Wiley‐Liss, Inc.
Expression of insulin‐like growth factor binding protein‐4 and ‐5 mRNAs in adult rat forebrain
Authors: Stenvers Kaye L. , Zimmermann Ellen M. , Gallagher Michela , Lund P. Kay 
Published: January 2005

AbstractAccumulating evidence indicates that the insulin‐like growth factors (IGFs) can act as neurotrophic factors. A family of at least six IGF binding proteins (IGFBPs) has been characterized. The IGFBPs prolong the half‐life of IGFs in plasma and may modulate IGF action in a cell‐ or tissue‐specific fashion. Two recently characterized IGFBPs, IGFBP‐4 and ‐5, have been shown by northern blot hybridization to be expressed in rat brain, but their cellular sites of synthesis are poorly characterized. Because IGFBP‐4 and IGFBP‐5 could potentially modulate IGF actions in the brain, we used in situ hybridization histochemistry and 35S‐labeled IGFBP‐4 and IGFBP‐5 riboprobes to localize sites of IGFBP‐4 and ‐5 mRNA expression in adult rat brain. The two IGFBP mRNAs are abundantly expressed within discrete regions of brain. The expression patterns of the two genes are largely nonoverlapping. Notably, IGFBP‐4 mRNA is highly expressed within hippocampal and cortical areas, whereas IGFBP‐5 mRNA is not detected above background in these areas. Within the hippocampus, abundant IGFBP‐4 mRNA expression is detected in pyramidal neurons of the subfields of Ammon's horn and the subiculum and in the granule cell layer of the anterior hippocampal continuation. In the cortex, IGFBP‐4 mRNA is widely expressed in most areas and layers. In contrast, IGFBP‐5, but not IGFBP‐4, mRNA is detected within thalamic nuclei, leptomeninges, and perivascular sheaths. The distinct expression patterns of IGFBP‐4 and ‐5 mRNAs within the brain suggest that these IGFBPs may modulate paracrine/autocrine actions of the IGFs in discrete brain regions or compartmentalization of the IGFs within the brain. © 1994 Wiley‐Liss, Inc.
The candelabrum cell: A new interneuron in the cerebellar cortex
Authors: Lainé Jeanne , Axelrad Herbert 
Published: January 2005

AbstractA new cell type is described in silver‐impregnated sections of the rat cerebellar cortex, uniformly distributed through all the cerebellar folia. The soma is rather small, roughly pyriform, vertically oriented, and squeezed, in a sandwich‐like manner, between the Purkinje cell somata. One or two thick dendrites arise from the upper pole of the cell body and course through the entire molecular layer, dividing into a few, slightly oblique, branches that can reach the pia mater. These dendrites are covered with irregularly distributed spines. Some more slender dendrites emerge from the lower part of the cell body, or from the proximal trunk of a molecular dendrite, and spread tortuously for a short distance in the upper granular layer. A thick initial segment emerges directly from the soma or from the proximal portion of a dendrite, the axon winding then horizontally through or just above the Purkinje cell layer. During this horizontal course it gives off vertically oriented beaded branches ascending through the major part of the molecular layer. These branches, rather closely spaced, occupy different parasagittal planes, separated by about 10 to 30 μm. This axonal arborisation can thus be compared with a candelabrum. The peculiar three‐dimensional spread of the axonal collaterals suggests a functional relationship between these branches and the dendritic trunks of neighbouring Purkinje cells. A comparative analysis of the morphological differences between this candelabrum interneuron and the other corticocerebellar interneurons found in the vicinity of the ganglionic layer confirms the specificity of this new cell class. © 1994 Wiley‐Liss, Inc.
The distribution of GABA‐containing perikarya, fibers, and terminals in the forebrain and midbrain of pigeons, with particular reference to the basal ganglia and its projection targets
Authors: Veenman C. Leo , Reiner Anton 
Published: January 2005

AbstractImmunohistochemical techniques were used to study the distributions of glutamic acid decarboxylase (GAD) and γ‐aminobutyric acid (GABA) in pigeon forebrain and midbrain to determine the organization of GABAergic systems in these brain areas in birds. In the basal ganglia, numerous medium‐sized neurons throughout the striatum were labeled for GABA, while pallidal neurons, as well as a small population of large, aspiny striatal neurons, labeled for GAD and GABA. GAD+ and GABA+ fibers and terminals were abundant throughout the basal ganglia, and GABAergic fibers were found in all extratelencephalic targets of the basal ganglia. Most of these targets also contained numerous GABAergic neurons. In pallial regions, approximately 10‐12% of the neurons were GABAergic. The outer rind of the pallium was more intensely labeled for GABAergic fibers than the core. The olfactory tubercle region, the ventral pallidum, and the hypothalamus were extremely densely labeled for GABAergic fibers, while GABAergic neurons were unevenly distributed in the hypothalamus. GABAergic neurons and fibers were abundant in the dorsalmost part of thalamus and the dorsal geniculate region, while GABAergic neurons and fibers were sparse (or lightly labeled) in the thalamic nuclei rotundus, triangularis, and ovoidalis. Further, GABAergic neurons were abundant in the superficial tectal layers, the magnocellular isthmic nucleus, the inferior colliculus, the intercollicular region, the central gray, and the reticular formation. GABAergic fibers were particularly abundant in the superficial tectal layers, the parvocellular isthmic nucleus, the inferior colliculus, the intercol‐licular region, the central gray, and the interpeduncular nucleus. These results suggest that GABA plays a role as a neurotransmitter in nearly all fore‐ and midbrain regions of birds, and in many instances the observed distributions of GABAergic neurons and fibers closely resemble the patterns seen in mammals, as well as in other vertebrates. © 1994 Wiley‐Liss, Inc.
Distribution and morphology of immunoreactive gonadotropin‐releasing hormone (GnRH) neurons in the basal forebrain of ponies
Authors: Melrose P. A. , Pickel C. , Cheramie H. S. , Henk W. G. , Littlefield‐Chabaud M. A. , French D. D. 
Published: January 2005

AbstractRecent reports have indicated that analysis of changes in the staining characteristics of gonadotropin‐releasing hormone (GnRH) neurons and characterization of morphological plasticity of the related structural framework may help to elucidate the physiological mechanisms involved in neuroendocrine control of mammalian reproduction. Whether comparative studies will facilitate this process or simply elucidate species‐specific mechanisms is not yet clear. The present study was performed in order to begin analysis of GnRH neurons in a seasonally breeding species that exhibits an unusually long ovulatory luteinizing hormone (LH) surge. To this end, light microscopy and image analysis were used to characterize distribution and morphology of GnRH neurons in 15 adult male and female ponies. Samples were collected in the middle of the normal ovulatory season. Unipolar, bipolar, and multipolar GnRH neurons were organized in a loosely defined continuum that extended from the medial septum to tuberoinfundibular areas in the medial basal hypothalamus (MBH). Most cells were bipolar, and the majority of neurons were located in the MBH. Fiber projections to the median eminence included presumptive pathways similar to those previously described in other species. Image analysis of cell size indicated that cells in the MBH were larger than those in preoptic areas and GnRH neurons in both of these locations were larger than neurons in rostral areas of the medial septum. Results from this experiment suggest that the large population of MBH GnRH neurons in the equine species is likely to be of primary importance to reproductive function, whereas cells in other areas are fewer and smaller. Further work is needed to characterize morphological characteristics that may be related to physiological fluctuations in reproductive function of the equine species. © 1994 Wiley‐Liss, Inc.