bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biphasic retinal neurogenesis in the brush‐tailed possum, Trichosurus vulpecula: Further evidence for the mechanisms involved in formation of ganglion cell density gradients
Authors: Harman Alison M. , Sanderson Ken J. , Beazley Lyn D. 
Published: January 2005

AbstractWe investigated cell generation in the retina of the brush‐tailed possum (Trichosurus vulpecula) by using tritiated (3H)‐thymidine labelling of newly generated cells. Animals aged between postnatal day (P) 5 and 85 each received a single injection of 3H‐thymidine. Following autoradiographic processing, maps of labelled cells were constructed from retinal sections. Retinal cell generation takes place in two phases, the first is concluding in the retinal periphery at P53 as the second is seen to commence in midtemporal retina. In the first phase, cells in central retina are generated earlier than those in peripheral regions. In the second phase, cells complete their final division in midtemporal retina first and in the periphery last. Cells generated in the first phase comprise virtually all cells in the ganglion cell layer, amacrine cells, horizontal cells, and cones.Ganglion cells are produced at a slightly earlier stage than displaced amacrine cells, horizontal cells, or cones. Amacrine cells in the inner nuclear layer are the final cells produced in the first phase. When ganglion cells and amacrine cells are pooled, their combined rate of production matches that of the other cell types. These data indicate that the ratio of displaced amacrine cells: horizontal cells: cones: combined ganglion cells and amacrine cells does not change throughout development. However, the ratio of ganglion cells:amacrines changes steadily as development proceeds to favour amacrine cells. In the second phase, sparse numbers of nonganglion cells in the ganglion cell layer and large numbers of bipolar and Müller cells are produced along with all rods.The two phases in the possum are similar to those seen in the wallaby, the quokka. However, fewer cells are added in central retina in the possum than in the quokka and cell addition continues for a more extended period in the periphery in the possum. We suggest that this difference in cell addition could account for the development of a more pronounced visual streak of retinal ganglion cells in the possum than in the quokka. A comparison of possum retinal cell generation with that of other marsupials adds support for the “homochrony theory.” © 1992 Wiley‐Liss, Inc.
Enkephalin‐immunoreactive neurons in the parvicellular subdivisions of the paraventricular nucleus project to the external zone of the median eminence
Authors: Merchenthaler Istváan 
Published: January 2005

AbstractThe enkephalin‐immunoreactive neurons that project to the external zone of the median eminence were identified on thin paraffin and thick vibratome sections using a combination of retrograde labeling with peripherally administered Fluoro‐Gold and immunocytochemistry. The vast majority of the enkephalin‐immunoreactive neurons that project to the external zone of the median eminence (ME) reside in the paraventricular nucleus (PVN) of the hypothalamus. Within the PVN, the majority of these hypophysiotropic neurons are located in the medial parvicellular subdivision. while a smaller number can be detected in the anterior and the periventricular subdivisions. Although many enkephalin‐immunoreactive neurons are present in other hypophysiotropic areas of the hypothalamus, such as the medial preoptic area, the anterior periventricular area, and the arcuate nucleus, only a few of these can be retrogradely labeled from the ME. These results provide morphological evidence for the key role of paraventricular enkephalin‐immunoreactive neurons in the regulation of neuroendocrine functions. © 1992 Wiley‐Liss, Inc.
Vasoactive intestinal peptide (VIP) in magnocellular neurons of the hypothalamo‐neurohypophysial system of the mink (Mustela vision) is co‐localized with vasopressin or oxytocin
Authors: Larsen Philip J. , Mikkelsen Jens D. 
Published: January 2005

AbstractThe distribution of vasoactive intestinal peptide (VIP) was analysed in perikarya of the mink hypothalamus with immunohistochemistry and, surprisingly, a large population of magnocellular VIP‐immunoreactive neurons was present in the paraventricular and supraoptic nuclei as well as in accessory hypothalamic nuclei. From perikarya in the paraventricular as well as supraoptic nuclei, a large number of VIP immunoreactive nerve fibers was observed to enter the hypothalamo‐neurohypophysial tract. Within the median eminence, a high density of VIP‐immunoreactive nerve fibers was present in the external and internal zones. Fibers in the external zone of the median eminence were endowed with varicosities and perivascular terminals, while fibers in the internal zone were smooth and without terminal specializations. From the internal zone of the median eminence, fibers coursed via the infundibular stalk to terminate in perivascularly situated terminals in the neurohypophysis. In addition, a substantial number of small VIP‐immunoreactive perikarya was observed within the suprachiasmatic nucleus. These perikarya were immunoreactive to neither vasopressin nor neurophysin. To elucidate the co‐existence of VIP‐immunoreactivity with vasopressin, oxytocin or neurophysin, a sequential double immunoperoxidase procedure to localize antigens with diaminobenzidine and benzidine dihydrochloride as chromagens was performed. From these experiments it was evident that VIP in nearly all magnocellular hypothalamo‐neurohypophysial neurons co‐existed with neurophysin. Based on a semi‐quantitative estimate, half the VIP‐immunoreactive magnocellular perikarya co‐stored vasopressin, while another half co‐stored oxytoxin.The present study describes the presence of a large population of VIP‐containing neurons in the hypothalamo‐neurohypophysial system of the mink. These findings raise evidence that within the mink, VIP may be involved in neurohypophysial physiology. © 1992 Wiley‐Liss, Inc.
Electron microscopic localization of photoaffinity‐labelled delta opioid receptors in the neostriatum of the rat
Authors: Pasquini F. , Bochet P. , Garbay‐Jaureguiberry C. , Roques B. P. , Rossier J. , Beaudet A. 
Published: January 2005

AbstractThe distribution of delta opioid receptors, selectively labelled in vitro with the photoaffinity probe monoiodo azido‐DTLET ([D‐Thr2, pN3Phe4, Leu5] enkephalyl‐Thr6), was analyzed by light and electron micrsocopic radioautography in sections from rat neostriatum. Preliminary experiments indicated that up to 65% of specific 125I‐azido‐DTLET binding to rat striatal sections was still detectable following prefixation of the brain with 0.5% glutaraldehyde. These experiments also showed that up to 20–30% of the specifically bound radioactivity was covalently linked following ultraviolet irradiation and was thereby retained in tissue during subsequent postfixation and dehydration steps. Accordingly, the topographic distribution of the covalently attached azido‐DTLET molecules was similar to that seen in fresh frozen sections and characteristic of that previously described for delta sites. Light and electron microscopic examination of the label in prefixed, striatal sections irradiated with ultraviolet light revealed that a significant proportion of specifically bound 125I‐azido‐DTLET molecules was intraneuronal. Specifically, 16% of the labelled binding sites were found in dendrites, 12% in perikarya and 4% in axon terminals. These results suggest that an important proportion of delta opioid binding sites labelled in the neostriatum correspond to receptors that are undergoing synthesis, transport and/or recycling. They also imply that a major fraction of delta sites are associated with intrastriatal neurons, as opposed to afferent axons. Approximately 44% of the labelled binding sites were associated with neuronal plasma membranes. Although most of these were found at the level of axodendritic (20%) and dendrodendritic (7%) appositions, comparison of the labelling incidence of these two compartments with their frequency of occurrence in tissue suggested that delta sites are fairly widely dispersed along neuronal plasma membranes. Only a small proportion (smaller than that of mu or kappa sites labelled in the same region) was associated with synaptic specializations. These results support the concept that delta receptors correspond to molecular entities that are distinct from mu and kappa sites and suggest that delta ligands act primarily nonjunctionally on the plasma membrane of striatal neurons. © 1992 Wiley‐Liss, Inc.
Axonal trajectories and distribution of GABAergic spinal neurons in wildtype and mutant zebrafish lacking floor plate cells
Authors: Bernhardt Robert R. , Patel Chetan K. , Wilson Stephen W. , Kuwada John Y. 
Published: January 2005

AbstractThe role of the midline floor plate cells in the neuronal differentiation of the spinal cord was examined by comparing putative GABAergic neurons in wildtype zebrafish embryos with those in cyc‐1 mutant embryos. The mutation produces a pleiotropic recessive lethal phenotype and is severe in rostral brain regions, but its direct effect in the caudal hindbrain and the spinal cord is apparently restricted to the depletion of the midline floor plate cells. In wildtype embryos, an antibody against the neurotransmitter GABA labeled the cell bodies, axons, and growth cones of three classes of previously identified neurons; dorsal longitudinal neurons (DoLA), commissural secondary ascending neurons (CoSA), and ventral longitudinal neurons (VeLD). A novel ventral cell type, Kolmer‐Agduhr (KA) neurons, was also labeled. In the cyc‐1 mutant, abnormalities were observed in some, but not all, of the GABAreactive CoSA, VeLD, and KA axons, while the axonal trajectories of DoLA neurons were not affected. Furthermore, the number of KA cells was reduced in the mutant while the numbers of the other GABAreactive cells were unperturbed. These observations corroborate our earlier hypothesis that the floor plate cells are one of several guidance cues that direct axonal outgrowth near the ventral midline of the spinal cord. They also suggest that the floor plate cells may play a role in the cellular differentiation of the spinal cord of zebrafish embryos. © 1992 Wiley‐Liss, Inc.
Immunofluorescent analysis of creatine kinase in cultured astrocytes by conventional and confocal microscopy: A nuclear localization
Authors: Manos Patricia , Edmond John 
Published: January 2005

AbstractThe subcellular localization of creatine kinase (CK) was examined in primary cultures of astrocytes with immunofluorescent labeling methods and detection by both standard fluorescence microscopy and confocal laser‐scanning microscopy. With conventional microscopy, the pattern of CK staining was uniform throughout the cell cytoplasm and appeared to stain the nuclear region intensely. Staining of CK in the nuclear region co‐localized with the DNA‐specific Hoechst nuclear stain. CK produced a diffuse cytoplasmic staining pattern that was different from the staining pattern produced by the cytoskeletal proteins glial fibrillary acidic protein and tubulin, both of which showed a filamentous cytoskeletal network that excluded the nucleus. To examine the structural details of CK in the nuclear region, serial optical sections were taken through the cell monolayer with a confocal microscope. The cells were immunostained for CK, and the CK‐staining pattern was compared with the staining pattern produced by propidium iodide, which is specific for DNA in RNase‐treated samples and stains total nucleic acid in untreated samples. CK staining was present within the nucleus in each section taken through the monolayer. The nucleolus did not stain for CK. The pattern of CK staining in the nucleus (and cytoplasm) was distinctly different from the staining pattern of either DNA or total nucleic acid. Nuclear CK appeared to have a granular, particulate pattern, which is suggestive of a nucleoplasmic distribution. © 1992 Wiley‐Liss, Inc.
Postnatal development of tyrosine hydroxylase immunoreactive amacrine cells in the rabbit retina: I. Morphological characterization
Authors: Casini Giovanni , Brecha Nicholas C. 
Published: January 2005

AbstractThe present and accompanying (Casini, G., and N.C. Brecha, J. Comp. Neurol. 326:302–313, 1992) papers investigate the postnatal development of tyrosine hydroxylase (TH)‐immunoreactive (IR) amacrine cells in the rabbit retina. This study is focused on a detailed analysis of the patterns of cellular growth and differentiation of TH‐IR amacrine cells, which serve as a model to gain insights into the mechanisms underlying developmental changes associated with the maturation of amacrine cells. Faintly staining TH‐IR neurons are present in the proximal inner nuclear layer of newborn retinas. They are characterized by a large nucleus and usually a single primary process lacking varicosities. At postnatal day (PND) 6, TH‐IR processes display more complex morphological characteristics, including a few varicosities, and second‐ and third‐order ramifications. Growth cones are often seen. At PNDs 10 and 12 (eye opening), TH‐IR cells have general morphological characteristics similar to adult TH‐IR amacrines. They display 2–5 primary processes, which start forming a complex network of fibers in lamina 1 of the inner plexiform layer (IPL). TH‐IR processes are also present in lamina 3 and rarely in lamina 5 of the IPL. Many fibers ending in growth cones are observed. In addition, very rare, thin TH‐IR fibers are present in the outer plexiform layer. At PND 19, TH‐IR fibers form a complex, dense network in lamina 1 of the IPL, and loose networks in laminae 3 and 5. Growth cones are not observed at this age. At PND 26, a few “ring‐like” structures formed by TH‐IR fibers in lamina 1 of the IPL are observed for the first time. In adult retinas, the “ring‐like” structures are more numerous than at PND 26. A second, rare type of TH‐IR cell (“type B”) is encountered in all retinal regions beginning at PND 10. These cells are characterized by weak immunostaining and a small soma size.The present findings show that a significant differentiation of TH‐IR neurons occurs during the first 10–12 PNDs. Eye opening is an important period for the maturation of TH‐IR amacrines and, more generally, for the maturation of the IPL. © 1992 Wiley‐Liss, Inc.
Morphological response of extending spinal neuritic growth cones to peripheral target tissue
Authors: Somasekhar Thummala , Pollack Emanuel D. 
Published: January 2005

AbstractNerve fibers extend from spinal cord explants of larval frog in an enhanced and directed manner when cocultured with limb mesenchyme target tissue. In order to gain a better understanding of the events involved in target directed neurite extension, a detailed examination of the nerve growth cone was undertaken. The growth cones of spinal neurites that had elongated in the presence or absence of target tissue were examined by light and electron microscopy. Scanning electron microscopy revealed that growth cones of cord + limb cultures were elaborate in form with numerous and long filopodia, while those cultured in the absence of the target tissue appeared relatively simple with few, short filopodia. A morphological parallel existed between those growth cones that were cultured without the target and those in cord + limb cultures but which grew from the side of the cord explant away from the mesenchyme tissue. When examined with the transmission electron microscope, growth cones under target influence were organelle‐rich in contrast to target‐deprived growth cones, which lacked the extensive array of vesicles, endoplasmic reticulum, and filaments. When the attachment substratum of polylysine was substituted by collagen, the dramatic differences in growth cones were not realized, although enhanced, oriented growth still occurred in the presence of limb target tissue. It appears that growth cone morphology is a dynamic reflection of the growth effects elicited by a target tissue factor that in turn may be mediated by the nature of the extracellular environment. © 1992 Wiley‐Liss, Inc.
Selective retrograde transport of nipecotic acid, a GABA analog, labels a subpopulation of gerbil olivocochlear neurons
Authors: Ryan Allen F. , Keithley Elizabeth M. , Schwartz Ilsa R. , Wang Zhi‐Xian 
Published: January 2005

AbstractPerfusion of the gerbil cochlea with micromolar quantities of 3H‐γ‐aminobutyric acid (GABA) results in rapid, selective labeling of 50–60% of the olivocochlear (OC) efferent terminals on afferent dendrites beneath the inner hair cells, and all of the efferent terminals beneath the outer hair cells. In order to identify the neurons from which these GABA‐accumulating terminals originate, the cell bodies were localized by using retrograde transport of 3H‐nipecotic acid, a metabolically inert GABA analog. With survival times of 6–30 hours after cochlear injection, myelinated OC efferent fibers and cell bodies were well labeled, with the greatest number being labeled at 12‐18 hours. All of the labeled neurons belonged to the medial OC system, and no lateral OC neurons were labeled. It is concluded that the GABA‐accumulating endings in the gerbil cochlea arise from medial OC neurons, and therfore that medial OC efferent neurons in this species project to both inner and outer hair cell regions. © 1992 Wiley‐Liss, Inc.
Distribution, of [3H]quinuclidinyl benzilate, [3H]nicotine, and [125I]alpha‐bungarotoxin binding sites in the nucleus tractus solitarii of the cat
Authors: Maley Bruce E. , Seybold Virginia S. 
Published: January 2005

AbstractThe distribution of muscarinic and nicotinic cholinergic binding sites in the cat nucleus tractus solitarii was studied by the technique of in vitro autoradiography. Using the antagonist [3H]quinuclidinyl benzilate, muscarinic binding sites were differentially located in subdivisions of the nucleus tractus solitarii. The majority of muscarinic binding sites were located predominantly in the caudal half of the nucleus, reaching their greatest amounts at the mid levels of the nucleus tractus solitarii. The medial, dorsolateral, intermediate, and interstitial subdivisions contained the highest densities of quinuclidinyl benzilate binding sites. Nicotinic cholinergic binding sites, using [3H]nicotine and [125I]alpha‐bungarotoxin, had unique patterns of distribution. With [3H]nicotine the majority of binding sites were located in rostral levels of the nucleus with very few binding sites present in the caudal half. In contrast, [125I]alpha‐bungarotoxin binding sites were present mainly in subdivisions located in the caudal half of the nucleus, i.e., commissural, ventrolateral, dorsolateral, medial, and intermediate subdivisions, and dropped off precipitously at more rostral levels. The differential distribution of [3H]nicotine and [125I]alpha‐bungarotoxin suggests the two ligands may be labeling different types of nicotinic binding sites in the nucleus tractus solitarii. The unique distribution of muscarinic and nicotinic cholinergic binding sites in the various subdivisions of the nucleus solitarii suggests that muscarinic and nicotine mechanisms may play an active role in the regulation of the diverse autonomic functions at the level of the nucleus tractus solitarii. © 1993 Wiley‐Liss, Inc.
Regional distribution of neural cell adhesion molecule (N‐CAM) and L1 in human and rodent hippocampus
Authors: Miller P. D. , Chung W.‐W. , Lagenaur C. F. , DeKosky S. T. 
Published: January 2005

AbstractCell surface adhesion molecules N‐CAM and L 1 are implicated in central nervous system (CNS) cell migration and axon outgrowth in in vitro and in vivo developmental studies. These molecules show a differential distribution during CNS development, thus suggesting that they subserve different roles in process outgrowth and tissue organization. A variety of N‐CAM isoforms are known, and individual N‐CAMs undergo posttranslational modification. Such changes and the potential for generating numerous molecules may mediate development of specific neural cell contacts and circuitry. We evaluated immunohistochemical staining of polyclonal antibodies to L 1 and N‐CAM, as well as monoclonal antibodies directed against embryonic N‐CAM and the 140 and 180 kDa species of N‐CAM in human, rat, and mouse hippocampus. Staining patterns in the three species were qualitatively similar, but staining in the mouse hippocampus was quantitatively greater for some epitopes. A distinctive pattern of staining was found, corresponding to the known anatomy of the structure. Total N‐CAM staining was intense in the hilus and inner molecular layer (ML) of the dentate gyrus with lighter staining in the dentate outer ML. The mossy fiber tract (MFT), comprising axons traveling from the dentate granule cells to CA3 pyramidal cells, was strongly stained by polyclonal antibody to N‐CAM. There was abundant staining of the stratum radiatum (SR) and stratum oriens (SO) of CA1, but stratum lacunosum moleculare (LM) showed very little staining. The monoclonal antibody 12F11, which recognizes the 140 and 180 kDa forms of N‐CAM, intensely stained the MFT, hilus, and inner ML. With 12F11, SO and SR stained uniformly throughout CA1, with much reduced staining in CA2 and CA3. There was little staining in LM. L1 staining was more evenly distributed throughout the hippocampus and dentate, with light hilar and MFT staining, and even staining through the SR and SO. Stratum LM stained intensely for L1, with a narrow clear zone between SR and LM. The ML of the dentate gyrus stained intensely with anti‐L1, with a discrete clear zone separating the inner and outer ML. Embryonic N‐CAM had little staining in CA1 but strong hilar and MFT staining; thus, this “embryonic” determinant continues to be expressed in limited regions in the adult. In contrast to the adult rodent hippocampus, human hippocampus exhibited embryonic N‐CAM in the outer two‐thirds of the ML, but showed very little staining in the hilar region. These distinctive patterns suggest that the distribution of the N‐CAM and L1 molecular species have clear‐cut structural and functional roles in the laminated circuitry of the hippocampus. (c) 1993 Wiley‐Liss, Inc.
Developmental study of the gene expression for α and γ subunits of enolase in the rat brain by in situ hybridization histochemistry
Authors: Watanabe Masahiko , Nagamine Tomoaki , Sakimura Kenji , Takahashi Yasuo , Kondo Hisatake 
Published: January 2005

AbstractThe gene expression for α and γ subunits of enolase, a dimeric enzyme in the glycolytic pathway, was examined in the developing brain of rats by in situ hybridization. The expression for the γ subunit of enolase was first detected in post‐mitotic neurons settled in the mantle zone at E13, and it increased progressively until the adult stage. Expression signals for the α subunit were discerned in two discrete regions showing different developmental changes: the signals in the proliferative ventricular zone were intense at E13 and decreased and eventually disappeared around birth, whereas the signals in the mantle zone persisted until the adult stage. In the adult brain, mRNAs for the α and γ subunits were expressed widely in neurons, resulting in almost similar temporal patterns in the brain except for the cerebellum. Expression levels of the α subunit in adult glial cells were below the detection threshold of the in situ hybridization analysis. These findings suggest that both α and γ enolase subunits participate in energy production in neurons of the mature brain and that marked changes in the subunit composition of enolase occur according to both neuron type and maturation. (c) 1993 Wiley‐Liss, Inc.