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Large Neurons (large + neuron)
Selected AbstractsDisabled-1 mRNA and protein expression in developing human cortexEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2003Gundela Meyer Abstract Disabled-1 (Dab1) forms part of the Reelin,Dab1 signalling pathway that controls neuronal positioning during brain development; Dab1 deficiency gives rise to a reeler-like inversion of cortical layers. To establish a timetable of Dab1 expression in developing human brain, Dab1 mRNA and protein expression were studied in prenatal human cortex. The earliest Dab1 signal was detected at 7 gestational weeks (GW), the stage of transition from preplate to cortical plate, suggesting a role of the Reelin,Dab1 signalling pathway in preplate partition. From 12 to 20 GW, the period of maximum cortical migration, Dab1 expression was prominent in the upper tiers of the cortical plate, to decline after midgestation. Radially orientated apical dendrites of Dab1-expressing neurons indicated a predominant pyramidal phenotype. Pyramidal cells in hippocampus and entorhinal cortex displayed a more protracted time of Dab1 expression compared to neocortex. In addition, at later stages (18,25 GW), Dab1 was also expressed in large neurons scattered throughout intermediate zone and subplate. From 14 to 22 GW, particularly high levels of Dab1 mRNA and protein were observed in cells of the ventricular/subventricular zone displaying the morphology of radial glia. The partial colocalization of vimentin and Dab1 in cells of the ventricular zone supported a radial glia phenotype. The concentration of Dab1 protein in ventricular endfeet and initial portions of radial processes of ventricular-zone cells points to a possible involvement of Dab1 in neurogenesis. Furthermore, a subset of Cajal,Retzius cells in the marginal zone colocalized Dab1 and Reelin, and may thus represent a novel target of the Reelin,Dab1 signalling pathway. [source] Allatostatin immunoreactivity in the honeybee brainTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 9 2010Sabine Kreissl Information transmission and processing in the brain is achieved through a small family of chemical neurotransmitters and neuromodulators and a very large family of neuropeptides. In order to understand neural networks in the brain it will be necessary, therefore, to understand the connectivity, morphology, and distribution of peptidergic neurons, and to elucidate their function in the brain. In this study we characterize the distribution of substances related to Dip-allatostatin I in the honeybee brain, which belongs to the allatostatin-A (AST) peptide family sharing the conserved c-terminal sequence -YXFGL-NH2. We found about 500 AST-immunoreactive (ASTir) neurons in the brain, scattered in 18 groups that varied in their precise location across individuals. Almost all areas of the brain were innervated by ASTir fibers. Most ASTir neurites formed networks within functionally distinct areas, e.g., the antennal lobes, the mushroom bodies, or the optic lobes, indicating local functions of the peptide. A small number of very large neurons had widespread arborizations and neurites were found in the corpora cardiaca and in the cervical connectives, suggesting that AST also has global functions. We double-stained AST and GABA and found that a subset of ASTir neurons were GABA-immunoreactive (GABAir). Double staining AST with backfills of olfactory receptor neurons or mass fills of neurons in the antennal lobes and in the mushroom bodies allowed a more fine-grained description of ASTir networks. Together, this first comprehensive description of AST in the bee brain suggests a diverse functional role of AST, including local and global computational tasks. J. Comp. Neurol. 518:1391,1417, 2010. © 2010 Wiley-Liss, Inc. [source] Allatostatin immunoreactivity in the honeybee brainTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 9 2010Sabine Kreissl Abstract Information transmission and processing in the brain is achieved through a small family of chemical neurotransmitters and neuromodulators and a very large family of neuropeptides. In order to understand neural networks in the brain it will be necessary, therefore, to understand the connectivity, morphology, and distribution of peptidergic neurons, and to elucidate their function in the brain. In this study we characterize the distribution of substances related to Dip-allatostatin I in the honeybee brain, which belongs to the allatostatin-A (AST) peptide family sharing the conserved c-terminal sequence -YXFGL-NH2. We found about 500 AST-immunoreactive (ASTir) neurons in the brain, scattered in 18 groups that varied in their precise location across individuals. Almost all areas of the brain were innervated by ASTir fibers. Most ASTir neurites formed networks within functionally distinct areas, e.g., the antennal lobes, the mushroom bodies, or the optic lobes, indicating local functions of the peptide. A small number of very large neurons had widespread arborizations and neurites were found in the corpora cardiaca and in the cervical connectives, suggesting that AST also has global functions. We double-stained AST and GABA and found that a subset of ASTir neurons were GABA-immunoreactive (GABAir). Double staining AST with backfills of olfactory receptor neurons or mass fills of neurons in the antennal lobes and in the mushroom bodies allowed a more fine-grained description of ASTir networks. Together, this first comprehensive description of AST in the bee brain suggests a diverse functional role of AST, including local and global computational tasks. J. Comp. Neurol. 518:1391,1417, 2010. © 2010 Wiley-Liss, Inc. [source] Localization of Vesicular Glutamate Transporter 2 mRNA in the Dorsal Root Ganglion of the Pigeon (Columba Livia)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 6 2009Y. Atoji Summary Our previous study showed localization of glutamate receptor 1 (GluR1) mRNA in neurons of the pigeon spinal cord, suggesting glutamatergic input from intrinsic and extrinsic origins. The present study examined localization of vesicular glutamate transporter 2 (VGLUT2) mRNA to confirm an extrinsic origin of glutamatergic neurons in the dorsal root ganglion (DRG). GluR1 and GluR2 mRNAs were examined in DRG and spinal cord to seek projection regions from VGLUT2 mRNA-expressing neurons. VGLUT2 mRNA was expressed in most DRG neurons and labelling intensity varied from weakly to intensely. Intense VGLUT2 mRNA expression was mainly seen in medium to large neurons. GluR1 and GluR2 mRNAs were expressed in the dorsal horn and GluR2 mRNA signal was also seen in the marginal nucleus. The results suggest that the pigeon DRG has an extrinsic glutamatergic origin that project to the dorsal horn and marginal nucleus of the spinal cord. [source] Canine Spinal Cord Neuron and Axon Myelin Sheath MorphometryANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2006A. C. De Francischini Carvalho Summary This inedited morphometric study has been developed from healthy canine spinal cord neuron cytoplasm and nucleus, and white matter axonal myelin sheath, from cervical, thoracic and lumbar regions. For the morphometric study, the parameters were area, perimeter, maximum and minimum diameters and roundness for neurons and myelin thickness for axon. For each parameter, 300 neurons were analysed. The results revealed that lumbar neurons had the highest mean values for the analysed parameters, indicating the presence of large neurons in this region, with large axons as a result of myelin thickness, which is proportional to axon calibre. We conclude that these morphometric results can contribute for the establishment of normal patterns, for canine spinal cord cervical, thoracic and lumbar segments. [source] | ||||||||||