bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyaxonal amacrine cells of rabbit retina: Morphology and stratification of PA1 cells
Authors: Famiglietti Edward V. 
Published: January 2005

AbstractPolyaxonal amacrine cells are a new class of amacrine cell bearing one to six branching, axon‐like processes, closely resembling the axons of Golgi type II cells found elsewhere in the central nervous system. Of the four types of polyaxonal amacrine cell that we have recognized in rabbit retina, three have been described previously in brief communications, and one is the subject of this paper.Type 1 polyaxonal (PA1) amacrine cells have larger cell bodies than most amacrine cells in Golgi preparations, averaging about 13 μm in diameter. These are typically positioned interstitially in the middle of the inner plexiform layer (IPL), although some are also found in the amacrine and ganglion cell layers. Axons and dendrites are broadly stratified in the middle of the IPL, in the vicinity of the a/b sublaminar border. Sparsely branching dendrites have a conventional appearance, branching at a narrow angle, and giving rise to smaller daughter branches, which taper gradually toward their termination. An unusual feature of the dendrites is the zig‐zag course of some terminal branches. Clusters of small, pedunculated spines are common on proximal dendrites, and spines are virtually absent on axons.Axons emerge from proximal dendrites within 50 μm of the soma, and more rarely from the soma, in a tapering initial segment, commonly interrupted by one or two large swellings. Subsequent branching is at a wide angle, and the fine caliber is maintained in the transition from parent to daughter branches. The uniform thickness of the axonal branches is interrupted at intervals by boutons en passant. Although the extent of the dendritic tree is large, exceeding 500 μm in radial extent from the cell body, for cells a few millimeters distant from the visual streak, the axonal tree is much larger, and its radial extent is measured in millimeters. PA1 amacrine cells are believed to be polarized in their functional organization, with a primarily recipient dendritic tree and a primarily transmissive axonal tree.PA1 amacrine cells co‐stratify with nab cone bipolar cells and with certain small tufted amacrine and ganglion cells at the a/b sublaminar border. The co‐stratification of both axons and dendrites at the a/b sublaminar border of the IPL suggests that PA1 amacrine cells are important modulators of neural activity in the middle of the IPL, affecting both ON and OFF responses, and perhaps ON‐OFF cells selectively.
Astrocytes in cat visual cortex studied by GFAP and S‐100 immunocytochemistry during postnatal development
Authors: Müller Christian M. 
Published: January 2005

AbstractA monoclonal antibody to glial fibrillary acidic protein (GFAP) and a polyclonal antiserum to the S‐100 protein were used to study the expression of these astrocytic proteins in the postnatal visual cortex of the cat. Three changes in antigen expression of these astroglial markers could be distinguished over development. First, the density of cells in the white matter, which are heavily labelled with both antibodies from birth until adulthood, diminishes after the third postnatal week. By intracellular filling with Lucifer Yellow the reduction of the cell density can be attributed to the disappearance of large astrocytes with a morphology of transforming radial glia, present only in early postnatal development. Second, heavily labelled, large cells present in the grey matter at the seventh postnatal day have disappeared by the fifth postnatal week. On the basis of their morphology these cells can also be classified as radial glial cells. Finally, astroglial cells of the adult‐like stellate form appear to be labelled in the cortical layers between the third and seventh postnatal weeks. While the density of these cells and the S‐100 immunoreactivity of the cell bodies is adult‐like at the fourth postnatal week, there is a gradual increase of the staining intensity with the GFAP antibody up to the seventh postnatal week. This developmental period is paralleled by the appearance of S‐100‐positive astrocytic processes. The gradual expression of GFAP immunoreactivity and the increased expression of S‐100 is interpreted as reflecting the time course of astrocytic maturation. A possible relation of the maturation of astrocytes and cortical development, both of which are prominent in the time period between the third and seventh postnatal week, is discussed.
Neurofilaments are prominent in bullfrog olfactory axons but are rarely seen in those of the tiger salamander, Ambystoma tigrinum
Authors: Burton Paul R. , Wentz Mark A. 
Published: January 2005

AbstractBullfrog olfactory axons show variable numbers (0–29) of structurally typical neurofilaments (NFs) about 10 nm in diameter. In studies tracking these NFs through serial sections of axons in cross section, they were found to be discontinuous, with a calculated average length of about 118 μm. In contrast to olfactory axons in bullfrogs, those of the tiger salamander Ambystoma trigrinum rarely show NFs. To be certain that the absence of NFs is a specific characteristic of olfactory axons, pieces of salamander spinal cord, optic nerve, and sciatic nerve were examined and found to contain typical NFs. To minimize the possibility that NFs in salamander olfactory axons were degraded or poorly fixed during preparation for electron microscopy, samples were fixed by using a variety of fixative and buffer combinations. To exclude the possibility that proteases degraded NFs during processing, prior to fixation some pieces of olfactory nerve were incubated in physiological saline containing protease inhibitors. Regardless of the preparation method, NFs were generally not seen in salamander olfactory axons. Extracts of salamander olfactory nerve were subjected to SDS‐polyacrylamide gel electrophoresis (PAGE) and immunoblotting studies with monoclonal antibodies to the three NF subunit proteins. The immunoblots showed negligible or trace amounts of NF‐L (light) and NF‐H (heavy), while an NF‐M (medium) protein having a molecular mass (Mr) of 160 kD was present in abundance. Extracts of salamander spinal cord, on the other hand, showed all three subunit proteins (with Mrs of 230, 160, and 77 kD). If one assumes that cells assemble structural elements to provide for a given function, the findings suggest that NFs in olfactory neurons of bullfrogs provide a function that may be missing in olfactory neurons of the salamander; the evidence also suggests that the absence of NFs in the salamander may be clue to a deficiency in two of the three NF subunit proteins.
Comparative distribution of messenger RNAs encoding glutamic acid decarboxylases (Mr 65,000 and Mr 67,000) in the basal ganglia of the rat
Authors: Mercugliano M. , Soghomonian J.‐J. , Qin Y. , Nguyen H. Q. , Feldblum S. , Erlander M. G. , Tobin A. J. , Chesselet M.‐F. 
Published: January 2005

AbstractGlutamic acid decarboxylase, the enzyme required for GABA synthesis, exists as distinct isoforms, which have recently been found to be encoded by different genes. The relative expression of messenger RNAs encoding two isoforms of glutamic acid decarboxylase (Mr 67,000 and Mr 65,000) was measured at the single‐cell level in neurons of the rat basal ganglia with in situ hybridization histochemistry. Both messenger RNAs were expressed in neurons of the striatum, pallidum, and substantia nigra pars reticulata, but marked differences in the relative level of labelling were observed with the two probes. In striatum, efferent neurons were more densely labelled for the messenger RNA encoding glutamic acid decarboxylase (Mr 65,000) than for the messenger RNA encoding glutamic acid decarboxylase (Mr 67,000), whereas the reverse was observed for GABA‐ergic interneurons. Neurons of the entopeduncular nucleus were much more densely labelled for messenger RNA encoding glutamic acid decarboxylase (Mr 65,000) than for messenger RNA encoding glutamic acid decarboxylase (Mr 67,000). In addition, labelling for messenger RNA encoding glutamic acid decarboxylase (Mr 65,000) was higher in the entopeduncular nucleus (internal pallidum) than in the globus pallidus (external pallidum), a structure which expressed similar levels of both mRNAs. In contrast to neurons of the internal pallidum, efferent neurons of the substantia nigra pars reticulata expressed slightly more messenger RNA encoding glutamic acid decarboxylase (Mr 67,000) than that encoding the other isoform of the enzyme. The results suggest a differential expression of the messenger RNAs encoding the two isoforms of glutamic acid decarboxylase in subpopulations of basal ganglia neurons in rats.
Antennular projections to the midbrain of the spiny lobster. II. Sensory innervation of the olfactory lobe
Authors: Schmidt Manfred , Ache Barry W. 
Published: January 2005

AbstractThe projection pattern of antennular sensory afferents in the olfactory lobe (OL) of the spiny lobster, Panulirus argus, was examined by backfilling axons in the antennular nerve (AN) with biocytin. Thin, presumptive olfactory afferents from the lateral division of the AN form a tract in the brain that diverges into a dense plexus that completely envelops the glomerular cortex of the OL. Most of the thin (diameter ≤ 0.3–1 μm) afferents project to single glomeruli. About 10% of the thin afferents, however, branch in the plexus and project to multiple glomeruli. A smaller number of medium‐sized to thick (diameter 2–10 μm), presumably mechanosensory, afferents also innervate the OL and co‐project to multiple glomeruli with the thin afferents. Afferents arborize profusely within the columnar glomeruli into very fine processes that penetrate to the base of the columns, but selectively terminate in either the cap/subcap region‐or in the innermost part of the base of the columns, often with conspicuous terminal boutons, forming two distinct regions of presumptive synaptic output. These results suggest that 1) The majority of the OL innervation is provided by olfactory sensilla (aesthetascs), but that other types of sensilla provide additional, likely mechanosensory, input to the OL. 2) The projection of olfactory afferents is not strictly uniglomerular. 3) The columnar organization of crustacean olfactory glomeruli is functionally significant and may provide an evolutionary correlate of the recently proposed subdivision of the vertebrate olfactory bulb into “functional columns”.
Restorative effects of reinnervation on the size and dendritic arborization patterns of axotomized cat spinal α‐motoneurons
Authors: Brännström Thomas , Havton Leif , Kellerth Jan‐Olof 
Published: January 2005

AbstractIn a preceding paper [Brännström, et al. (1992) J. Comp. Neurol. 318:439–451] a marked reduction in dendritic size was observed in cat spinal motoneurons following permanent axotomy. The aim of the present study was to analyse the possible restorative effects of peripheral reinnervation on the size and dendritic branching patterns of cat spinal motoneurons which had been deprived of neuromuscular contact for an extended period of time.In adult cats the medial gastrocnemius (MG) nerve was transected and ligated. After 6 weeks the nerve was allowed to reinnervate its muscle through a nerve graft. With approximately 6 weeks needed for muscle reinnervation [Foehring, et al. (1986) J. Neurophysiol. 55:947–965], the MG motoneurons were devoid of neuromuscular contact for altogether about 12 weeks. Two years later reinnervated MG α‐motoneurons were intracellularly labelled with horseradish peroxidase to allow quantitative analyses of the cell bodies and dendritic trees. Comparisons were made with previous data from normal and permanently axotomized MG motoneurons.The reinnervated motoneurons exhibited positive correlations between dendritic stem diameter, on one hand, and combined length, volume, membrane area, and number of end branches of the whole dendrite, on the other. By using the regression equations for these correlations, the total dendritic size of whole reinnervated motoneurons could be estimated. Such calculations showed that in comparison with the reduction in dendritic size found at 12 weeks after permanent axotomy (Brännström et al., see above), peripheral reinnervation caused the dendritic volume and membrane area to return to normal values. However, the values for combined dendritic length and number of dendritic end branches were still reduced by more than 25% as compared to the normal situation.The results indicate that following reinnervation of the target muscle, the axotomized motoneurons did not recover their original number of dendritic branches. The normalization of dendritic membrane area and volume was instead accomplished by two other mechanisms, namely an increase in dendritic diameters and an increased number of dendrites per neuron.
Somatic sensory responses in the rostral sector of the posterior group (POm) and in the ventral posterior medial nucleus (VPM) of the rat thalamus: Dependence on the barrel field cortex
Authors: Diamond Mathew E. , Armstrong‐James Michael , Budway Matthew J. , Ebner Ford F. 
Published: January 2005

AbstractThe projection from the whiskers of the rat to the S‐I (barrel) cortex is segregated into two separate pathways—a lemniscal pathway relayed by the ventral posterior medial nucleus (VPM) to cortical barrels, and a paralemniscal pathway relayed by the rostral sector of the posterior complex (POm) to the matrix between, above, and below barrels. Before investigating how the barrel cortex integrates these sensory pathways, it is important to learn more about the influence of the various inputs to the two thalamic nuclei. Based on the greater density of descending versus ascending projections to POm, it seemed likely that corticofugal inputs play an important role in the sensory activity of POm. To test this, the responses of POm and VPM cells to sensory stimuli were measured before, during, and after suppression of the S‐I cortex. S‐I was suppressed by application of magnesium or by cooling; the status of the barrel cortex was assessed continuously by an electrocorticogram. All VPM cells (n = 8) responded vigorously to whisker movement even when the barrel cortex was profoundly depressed. In contrast, all POm cells (n = 9) failed to respond to whisker movement once the barrel cortex became depressed, typically about 25 minutes after the start of cortical cooling or magnesium application. POm cells regained responsiveness about 30 minutes after the cessation of cortical cooling or the washoff of magnesium. These findings indicate that the transmission of sensory information through the lemniscal pathway occurs independently of the state of cortex, whereas transmission through the paralemniscal pathway depends upon the state of the cortex itself. © 1992 Wiley‐Liss, Inc.
Structural changes of the soleus and the tibialis anterior motoneuron pool during development in the rat
Authors: Westerga J. , Gramsbergen A. 
Published: January 2005

AbstractThe morphological development of motoneuron pools of two hindlimb muscles of the rat, soleus (SOL) and tibialis anterior (TA), was studied in rats ranging in age between 8 and 30 postnatal days (P8—P30). Motoneurons were retrogradely labelled by injecting a cholera toxin B subunit solution directly into the muscles. This resulted in extensive labelling of motoneurons as well as their dendritic trees.The distribution of cross sectional areas of neuronal somata was determined for both muscles at various ages. Somal size increased considerably between P8 and P12, whereas growth was moderate between P12 and P20. The size distribution of SOL motoneurons was bimodal from P20, whereas the size distribution of TA motoneurons remained largely unimodal.The morphological development of the dendritic tree was studied qualitatively. The development of dendritic arborization within the SOL and the TA motoneuron pool showed major differences. The arborization pattern of dendrites of TA motoneurons was basically multipolar at all ages. In contrast, dendrites of SOL neurons tended to line up with the rostro‐caudal axis and became organized in longitudinal bundles from P16 onwards.The relatively late appearance of dendrite bundles in the soleus motoneuron pool suggests that they might be related to the fine‐tuning of neuronal activity rather than patterning of motor activity. The occurrence of dendrite bundles in SOL and not in TA motoneuron pools suggests that they may be related to the different afferent organization of this postural muscle or to its tonic activation pattern. © 1992 Wiley‐Liss, Inc.
Segmental distribution and peptide content of primary afferent neurons innervating the urogenital organs and colon of male rats
Authors: Keast J. R. , de Groat W. C. 
Published: January 2005

AbstractMany visceral afferent neurons contain peptides, which have been proposed as histochemical markers for nerve pathways of particular targets or as transmitter candidates. The former possibility was investigated in the present study. Primary afferent neurons which project to the urinary bladder, distal colon or penis of rats, and the colon of cats were labelled with retrogradely transported fluorescent dyes (Fast Blue, True Blue, or Fluoro Gold). One to six weeks after dye injection into the organs, lumbosacral dorsal root ganglia were removed, treated with colchicine, and processed for immunohistochemical identification of five peptides. Dye‐labelled neurons were distributed in an organ‐specific manner in the lower lumbosacral ganglia, where colon afferent neurons were almost exclusively found in S1 ganglia, penis neurons primarily in L6, and bladder neurons at both levels. Substance P‐ (SP), calcitonin gene‐related peptide‐(CGRP), vasoactive intestinal peptide‐ (VIP), enkephalin‐ (ENK), and somatostatin‐ (SOM) immunoreactivity (IR) were detected in neurons in all lumbosacral ganglia but only some of these peptides were present in a large percentage of labelled neurons. The numbers of peptide‐containing neurons innervating each organ were CGRP > SP > VIP > ENK > SOM; however some differences were observed in the relative proportions of these neuronal populations between upper lumbar and lower lumbosacral ganglia and between different organs. The major difference seen at the upper lumbar level was amongst the SP‐IR neurons, which were common (25–30%) amongst bladder and colon afferent neurons but absent in penis neurons. At the lower lumbar‐sacral level CGRP‐IR was present in a greater proportion (70%) of colon neurons than neurons which supplied the bladder (52%) or penis (35%). VIP‐IR was found in fewer (2–12%) neurons of each group. The afferent innervation of the cat colon exhibited a similar peptide distribution but with smaller numbers of CGRP‐IR neurons (45% vs. 70%) and larger numbers of VIP‐ (18% vs. 2%) and ENK‐IR (5% vs. 0–2%) neurons. SOM‐IR was rarely found in any dye‐labelled neurons and may therefore be more important in the sensory supply of other pelvic organs or of somatic organs. In summary, these studies have revealed that primary afferent neurons supplying the urogenital organs and colon of male rats differ in their segmental distribution and also exhibit some differences in the percentage of cells containing certain peptides (SP, CGRP, and VIP). © 1992 Wiley‐Liss, Inc.
Effects of ethanol on development of dorsal raphe transplants in oculo: A morphological and electrophysiological study
Authors: Backman C. , Granholm A.‐C. 
Published: January 2005

AbstractThe purpose of this project was to investigate ethanol influence on the development of serotonin‐containing (5‐HT) neurons of the dorsal raphe nucleus in rat. Fetal tissue of embryonic day 17 from the dorsal brainstem was grafted to the anterior chamber of the eye of adult albino rats. The experimental group was exposed to 16% ethanol in the drinking water, and the control group received water ad libitum. After 4 weeks, morphological and electrophysiological evaluations were performed. Immunohistochemical analysis showed that 5‐HT‐immunoreactive fibers from ethanol treated transplants had a disturbed outgrowth pattern into the host iris as compared to the control group. Furthermore, the outgrowth area and axon bundle formation was significantly greater in the control group than in the ethanol group. Electrophysiological recordings revealed a dose‐dependent biphasic effect of locally applied ethanol on transplanted monoaminergic neurons. Low doses of ethanol (0.5–3 mM)induced an increase in basal firing rate of control neurons, while higher doses (10–100 mM)caused inhibition. However, monoaminergic neurons in the ethanol group showed a decreased neuronal sensitivity to locally applied ethanol. The same dose of locally applied ethanol which produced an excitation of neuronal activity in the ethanol transplants produced an inhibition in the control grafts. The dose‐response curve was shifted to the right. The present results suggest that chronic ethanol exposure during early development leads to altered axonal outgrowth from brainstem 5‐HT neurons, as well as decreased sensitivity of these neurons to locally applied ethanol.
Immunocytochemical demonstration of neural cell adhesion molecule (NCAM) along the migration route of luteinizing hormone‐releasing hormone (LHRH) neurons in mice
Authors: Schwanzel‐Fukuda Marlene , Abraham S. , Crossin K. L. , Edelman G. M. , Pfaff D. W. 
Published: January 2005

AbstractContact between the developing forebrain and the ingrowing central processes of the olfactory, vomeronasal and terminal nerves is preceded by a migration of neural cell adhesion molecule (NCAM)‐immunoreactive cells from the epithelium of the olfactory pit and the formation of an NCAM‐immunoreactive cellular aggregate in the mesenchyme between the olfactory pit and the forebrain. The axons of the olfactory, vomeronasal, and terminal nerves, also NCAM‐immunoreactive, grow into the cellular aggregate, which as development proceeds, becomes continuous with the rostral tip of the forebrain. The lateral and more rostral part of the cellular aggregate receives the ingrowing axons of the olfactory nerves and becomes the olfactory nerve layer of the olfactory bulb. The medial, more caudal part receives the central processes of the vomeronasal and terminal nerves. The vomeronasal nerve ends in the accessory olfactory bulb. The central processes of the terminal nerve end in the medial forebrain. Luteinizing hormone‐releasing hormone (LHRH)‐immunoreactive neurons, like the vomeronasal and terminal nerves, originate from the medial part of the olfactory pit. These LHRH cells migrate into the brain along and within a scaffolding formed by the NCAM‐immunoreactive axons of the vomeronasal and terminal nerves, and they are never seen independent of this NCAM scaffold as they cross the nasal lamina propria.The results suggest that: (1) NCAM is likely to be necessary for scaffold formation, and (2) the scaffold may be essential for the subsequent migration of LHRH neurons into the brain. Because they aggregate, migrating LHRH‐immunoreactive neurons, on which we did not detect NCAM immunoreactivity, may interact via other cell adhesion molecules (CAM). Inasmuch as the interaction between the LHRH‐immunoreactive neurons and the NCAM‐immunoreactive scaffold is heterotypic, the possibility of a heterophilic (NCAM to other CAM) interaction is not ruled out. These findings focus our attention on the functional role of NCAM in this migratory system. © 1992 Wiley‐Liss, Inc.