bluuebunny/crossref_metadata_2025 huggingface dataset:
Topographical organization of ascending cerebellar projections from the dentate and interposed nuclei in Macaca mulatta: An anterograde degeneration study
Authors: Stanton Gregory B.
Published: May 2005

Discrete electrolytic lesions were placed in the dentate and interpositus cerebellar nuclei in the monkey Macaca mulatta and anterograde degeneration was traced in the ascending limb of the brachium conjunctivum using the Wiitanen technique. The dentate and interpositus anterior (IA) nuclei project topographically onto the two somatotopically organized divisions of the red nucleus and the ventrolateral‐ventral intermediate nuclei of the thalamus (VL‐Vim). Caudal parts of the dentate project to face areas in medial parts of the parvocellular red nucleus (RNpc) and VL‐Vim, rostrolateral parts to central arm areas in these nuclei. There is a small projection from the rostroventral dentate to lateral hindlimb areas in RNpc and VL. Dorsal parts of the dentate project to ventral parts of RNpc and VLc‐Vim (distal limb musculature area) exclusively, whereas ventral parts of the dentate project to dorsal parts of RNpc with some overlap ventrally dorsomedial VLc (proximal limb musculature and premotor areas). Caudal parts of IA project to medial forelimb and rostral parts to lateral hindlimb areas in the magnocellular red nucleus (RNmc) and VL‐Vim. Projections from IA are greatest to distal musculature areas in VL‐Vim. No projections from the interpositus posterior nucleus (IP) to the red nucleus could be identified positively, but projections to VL‐Vim are to proximal hindlimb musculature and premotor areas.
Denervation of non‐optic brain areas along the course of the optic tract does not affect the success of optic nerve regeneration in frogs
Authors: Bohn Ronald C. , Stelzner Dennis J.
Published: May 2005

Unsuccessful axonal regeneration in frog or goldfish spinal cord is thought to be due in part to inappropriate denervated synaptic sites attracting regenerating axons as they pass by the lesion zone (Bernstein and Bernstein, '69; Bernstein and Gelderd, '73). The reported success of optic nerve regeneration in these same animals may result because there are no inappropriate synaptic sites available to the regenerating axons. To test for this we denervated areas within thalamus and mesencephalon which lie along the path of regenerating optic axons to determine whether or not abnormal connections would form in these areas and affect the success of optic nerve regeneration. After transection of the brainstem through the isthmal region, terminal degeneration was found in several zones adjacent to optic nerve targets or the optic tract (i.e., nucleus rotundus, corpus geniculatum laterale, and torus semicircularis). In adult frogs receiving left isthmal transection, we also crushed the right optic nerve and then examined the regenerated optic projection at intervals up to six months after nerve crush using anterograde transport of 3H‐proline. In no instance did the regenerating optic axons alter their distribution within visual neuropil zones or invade those areas deafferented by the isthmal lesion. Histological study showed that the axons cut by the isthmal lesion did not regenerate back to their sites to prevent the invasion of optic axons into these zones. We then attempted to force optic axons into foreign territory by removing a major projection zone, the optic tectum. With tectal ablation and isthmal transection, regenerating optic axons were offered synaptic space made available by both lesions. However, we found abnormal optic projections only in the middle and posterior thalamic neuropil and in the remaining tectal hemisphere. Optic axons did not expand into any of the areas deafferented by the isthmal transection, even though some of them were further denervated by the tectal ablation. We conclude that optic axons will not invade non‐optic areas deafferented by an isthmal lesion even if a large number of optic axons have no normal target to innervate.
Differentiation of an identified sensory neuron (SR) and associated structures (CTO) in grasshopper embryos
Authors: Heathcote R. David
Published: May 2005

The differentiation of an identified sensory neuron, the grasshopper wing hinge Stretch Receptor (SR), is examined throughout embryogenesis. The morphological features of the SR axon, as it finds its path from the peripheral cell body to the CNS, and the timing of this peripheral growth were determined by intracellular injection of Lucifer yellow. The course of growth of the SR axon within the CNS and the sequence of formation of the identified branches in its characteristic central arborization were investigated by silver intensification of cobalt‐stained axons. In addition, intracellular recording from the cell body of SR was used to determine the onset of electrical excitability and the characteristics of the somal action potential. A brief account of the differentiation of the closely associated wing hinge Chordotonal Organ is also given.

During differentiation, the cell bodies of SR and the first wing hinge Chordotonal Organ neuron (CTN1) extend processes and migrate posteriorly along a peripheral epithelial ridge. The cell bodies migrate up to 150 m̈m with a group of undifferentiated cells to a specific site at the posterior edge of the segment.

As the SR and CTN1 cell bodies migrate, their trailing axons stretch across the epithelial ridge. These axons form the medial body wall nerve (1D2) that the axons of subsequent sensory neurons follow.
Identification of and interactions between noradrenergic and serotonergic neurites in the myenteric plexus
Authors: Gershon Michael D. , Sherman Diane L.
Published: May 2005

Interactions between enteric noradrenergic and serotonergic neurites in the myenteric plexus were examined. The influence of exogenous norepinephrine (NE) and endogenously released NE on the release of 3H‐serotonin (3H‐5‐HT) from electrically stimulated, everted segments of guinea pig small intestine were analyzed. In addition, methods were employed to permit the ultrastructural identification of enteric serotonergic and noradrenergic neurites. These included electron microscopic radioautographic localization of 3H‐5‐HT in gut from animals treated with 6‐hydroxydopamine (6‐HD; 100 mg/kg) and examination of NaMnO4‐fixed tissue from animals given desmethylimipramine and the indolic neurotoxin, 5, 7‐dihydroxytryptamine (5,7‐DHT). Exogenous NE antagonized the stimulated release of 3H‐5‐HT; this action was mediated through alpha adrenoceptors. Evidence was obtained, however, that endogenous NE liberated from sympathetic postganglionic nerve terminals had a different action on the stimulated release of 3H‐5‐HT from that of exogenous NE. Endogenous NE appeared to facilitate 3H‐5‐HT release through an action on beta adrenoceptors. Terminals identified as probably serotonergic by radioautographic labeling with 3H‐5‐HT or by loading with 5,7‐DHT were most often found to end on neuronal somata or proximal dendrites. Synaptic specializations were found by radioautography in these locations. Terminals, dendrites, and cell bodies that took up 5,7‐DHT could be identified in NaMnO4‐fixed material that also permitted the simultaneous recognition of noradrenergic varicosities. Apparent noradrenergic‐serotonergic axoaxonic contacts were found by means of this double‐labeling technique. Together with the results of the experiments on the release of 3H‐5‐HT, these anatomical observations suggest that noradrenergic axons form facilitatory axoaxonic synapses with enteric serotonergic neurons.
Granule cells in the rat olfactory tubercle accumulate 3H‐γ‐aminobutyric acid
Authors: Krieger Neil R. , Megill John R. , Sterling Peter
Published: May 2005

The rat olfactory tubercle contains high concentrations of γ‐aminobu‐tyric acid (GABA) and its synthetic enzyme, glutamic acid decarboxylase (GAD). We previously demonstrated that GABA and GAD are most concen‐trated in the polymorphic layer of the tubercle and relatively absent from the plexiform and pyramidal layers. Here we report that the granule cells (the islands of Calleja) in the polymorphic layer.accumulate 3H‐GABA.

3H‐GABA Ci/mmole; 1.5 μ1 was injected trie tubercle and an hour later the rat was perfused with a mixture of paraformaldehyde and glu‐taraldehyde. The tissue was osmicated, dehydrated, and embedded in epon. Silver grains were sparse over the pyramidal and polymorphic cell bodies but numerous over the granule cell bodies in the islands of Callejaanddendrites in the surrounding.neuropjl. Grain densities for the granule cells were 41/100 μm3 compared to 4.2 for pyramidal and polymorphic cells. Witnm the island, all the granule cells appeared to be labeled. These results, com‐bined with previous demonstrations of the presence in this region of endo‐genous GABA and GAD, suggest that the granule neurons of the rat olfac‐tory tubercle are GABA‐ergic. These neurons also appear to receive dopamine input and therefore form part of a circuit that includes targets for both major and minor tranquilizers.
Commissural inhibition and facilitation of granule cell discharge in fascia dentata
Authors: Douglas R. M. , McNaughton B. L. , Goddard G. V.
Published: May 2005

Stimulation of the contralateral hippocampus in the hilar region had a marked effect on granule cell excitability in the fascia dentata. The primary effect was to block the population spike that otherwise occurred in response to perforant path stimulation. In contrast, the size of the excitatory post‐synaptic potential component of the perforant path‐evoked field potential was only slightly reduced. The population spike diminution began at short latency (3.5 msec), beginning at about 1.0 msec after the onset of the slow component of the potential evoked by the contralateral stimulus. The completeness and duration of this population spike diminution depended on the contralateral stimulus intensity. The maximum duration was less than 40 msec in unanesthetized rats and more than 100 msec in rats under pento‐barbital anaesthesia. Bicuculline did not diminish the field potential evoked bythe contralateral stimulus but it did prevent the stimulus from blocking the perforant path population spike and, instead, permitted a weak facilitation of the population spike. The normal reduction of the population spike was not mediated by recurrent inhibition, secondary to granule cell activation, since it occurred whether or not the granule cells were inhibited at the time of contralateral stimulation. These results imply that the initial main effect on fascia dentata granule cells of activity in the contralateral hilus is a γ‐aminobutyric‐acid‐mediated inhibition. This effect most probably involves commissural excitation of local inhibitory interneurons. The direct excitatory action of commissural fibers on granule cells, by comparison, is very weak.
Lectin cytochemistry and freeze‐fracture study of phagocytosis in the rat retina
Authors: McLaughlin Barbara J. , Boykins Lou G.
Published: May 2005

Lectin cytochemistry and freeze‐fracture intramembrane morphology have been studied in adult rat retinas during various stages of the phagocytic cycle. Animals were perfused with aldehydes at various times during the first 6 hours of light and the retinas were removed. Chopped sections of tissue were stained with one of two lectin‐peroxidase conjugates: ricinis communis agglutinin (RCA), which is specific for n‐acetylgalactosamine and galactose, or wheat germ agglutinin (WGA), which is specific for n‐acetylglucosamine and sialic acid. Other sections were frozen and prepared for freeze fracture.

During the first hour of light onset, numerous phagosomes are already present in the retinal pigment epithelial (RPE) cytoplasm. The engulfment stages of phagocytosis whereby the RPE microvilli wrap around and enclose shed rod outer segment (ROS) tips are rarely observed at this time. Newly formed phagosomes are present in the apical RPE cytoplasm while older and more osmiophilic phagosomes are located deeper within the RPE cytoplasm. Between 2 and 4 hours of light onset fewer phagosomes are present in the RPE cytoplasm, but it is common to observe many ROS tips in various stages of microvillous engulfment. By 6 hours phagosomes are rarely present but some engulfed ROS tips continue to be observed. Both RCA and WGA stain RPE microvilli and plasma membranes of photoreceptor outer segments. WGA, in addition, labels some intradisc membranes of intact and also shed outer segments that are being engulfed but does not label disc membranes in phagosomes. At all times, phagosomes are rimmed by both lectin stains, but their internal contents are never stained. Lysosomes and multivesicular and residual bodies are labeled by both lectins. Freeze‐fractured retinas show that as the ROS tips are engulfed, particle‐free areas are present on disc P‐face (cytoplasmic) membranes. Many newly formed phagosomes also display particle‐free membrane areas and older phagosome membranes are completely devoid of particles. These observations show that the changes in WGA staining and intramembrane particle distribution on disc membranes occur in retinas during phagocytosis and suggest that some membrane component that is present for the initial phagocytic interaction may be rapidly degraded thereafter.
Myelin breakdown and elimination in the posterior funiculus of the adult cat after dorsal rhizotomy: A light and electron microscopic qualitative and quantitative study
Authors: Franson Peter , Ronnevi Lars‐Olof
Published: May 2005

Adult cats were subjected to unilateral dorsal L6, L7, and S1 rhizotomy. After survival times of 1‐1,552 days the degeneration of axons and myelin sheaths and the elimination of degenerating myelin was studied qualitatively and quantitatively with light and electron microscopy and in Marchi‐stained sections in the posterior funiculus in T12‐L2.

Degeneration was first observed as swollen or shrunken nerve fibers. Somewhat later there was an increased occurrence of collapsed myelin sheaths. The latter lost their myelin periods and appeared to be transformed into myelin bodies. The occurrence of myelin bodies coincided temporally with the presence of many Marchi‐positive bodies. Later, an increasing number of intracellularly located lipid droplets occurred, paralleled by the occurrence of a great number of Marchi‐positive granules and crystalline structures.

Profiles of collapsed myelin sheaths, myelin bodies, and lipid droplets were frequently seen in the cytoplasm of microglial cells. Later, astrocytes and perivascular cells became filled with numerous lipid droplets.

The findings suggest that microglial cells take up collapsed myelin sheaths and within these cells the sheaths become transformed into myelin bodies and subsequently into lipid droplets. These two products of myelin disintegration appear to correspond to the Marchi‐positive structures seen during the degeneration process. The lipid droplets appear to be transported to astrocytes and perivascular cells.
Synaptic contacts between bipolar and photoreceptor cells in the retina of Callionymus lyra L.
Authors: Van Haesendonck E. , Missotten L.
Published: May 2005

A combined light and electron microscopic study of Golgi‐impregnated retinas of the marine teleost Callionymus lyra L. revealed mixed bipolar cells (M types) contacting rods and cones and pure cone bipolar cells (C types). Five types of mixed bipolar cells can be differentiated on the basis of their synaptic contacts. Two out of the five mixed bipolar cell types contact double cones, single cones, and rods (mixed, dark, pale, single [Mdps and midget‐Mdps]). Their endbuds make narrow cleft junctions, with each type of photoreceptor, and in addition, two endbuds end centrally in the synaptic ribbon complexes of the dark and pale double‐cone pedicles. Three types of mixed bipolar cells contact only double cones and rods. The endbuds of one type (mixed, dark, pale, ribbon [Mdpr]) end centrally in the synaptic ribbon complexes of the dark and pale double‐cone pedicles as well as of the rod spherules. The endbuds of two types (Mdp and midget‐Mdp) make wide cleft junctions in dark and pale double‐cone pedicles and in rod spherules. All pure cone bipolar cell types contact cones exclusively with narrow cleft junctions. Four types are seen: a type that contacts predominantly pale double‐cone pedicles but also a few dark double‐cone pedicles (Cp), a type that is connected with dark and pale double‐cone pedicles in about equal numbers (Cdp), a type that makes synaptic contacts with pale double‐cone pedicles and single‐cone pedicles (Cps), and a type that is connected with both types of double cones and to single‐cone pedicles (Cdps). A resemblance between the ultrastructural features of mixed bipolar cell synapses in Callionymus and in Carassius auratus is noted.
Some observations on the course and composition of the cingulum bundle in the rhesus monkey
Authors: Mufson Elliott J. , Pandya Deepak N.
Published: May 2005

The course and composition of the cingulum bundle was examined by using the autoradiographic tracer technique in the rhesus monkey. The cingulum bundle is observed to consist of three major fiber components originating from thalamus, cingulate gyrus, and cortical association areas. Following isotope injections in the anterior and lateral dorsal thalamic nuclei, labelled fibers form an arch in the white matter behind the cingulate sulcus and occupy the ventral sector of the cingulum bundle. The fibers from the anterior thalamic nucleus coursing in the cingulum bundle extended rostrally to the frontal cortex and caudally to area 23 and the retrosplenial cortex. In contrast, the fibers from lateral dorsal nucleus reached the retrosplenial cortex as well as the parahippocampal gyrus and presubiculum. Efferent fibers from the cingulate gyrus occupy a dorsolateral sector of the cingulum bundle. Those fibers from area 24 of the cingulate gyrus are directed to the premotor and prefrontal regions as well as area 23 and retrosplenial cortex. The fibers from area 23 extend rostrally to the prefrontal cortex and caudoventrally to the presubiculum and parahippocampal gyrus. Finally, an association component originates mainly from prefrontal cortex and posterior parietal region. These fibers occupy a more dorsal and lateral periphery in the cingulate white matter. Cingulum bundle fibers from the prefrontal cortex extend up to the retrosplenial cortex while those from the posterior parietal cortex extend caudally to the parahippocampal gyrus and presubiculum, and rostrally up to the prefrontal cortex.
Electron microscopic and immunohistochemical evidence that unmyelinated ventral root axons make U‐turns or enter the spinal pia mater
Authors: Risling M. , Dalsgaard C.‐J. , Cukierman A. , Cuello A. C.
Published: May 2005

The occurrence of unmyelinated and small myelinated axons and of nerve fibres with a substance P‐like immunoreactivity was studied in juxtamedullary L7 ventral root fascicles and surrounding pia mater of kittens and cats. Electron microscopic analysis of thin transverse serial sections from this region in adult cats showed that the number of unmyelinated axon profiles decreases rapidly as the CNS is approached, reaching zero near or at the CNS/PNS border. No unmyelinated axons were found to enter the CNS through this root. At least to some extent, the disappearance of unmyelinated ventral root axons from the juxtamedullary root fascicles was due to presence of intrafascicular axonal hairpin loops and to a shift of axons from ventral root fascicles to the pia mater. It was also found that, as in the L7 ventral root, the content of unmyelinated axons in the pia mater is lower in kittens than in cats. Fluorescence microscopic examination of specimens incubated with substance P antiserum showed that some looping axons and ventral root‐pia mater axons were substance P immunoreactive. These observations suggest the hypothesis that sensory unmyelinated axons might grow through the L7 ventral root and enter the pia mater during postnatal development. Moreover they show that the occurrence of sensory unmyelinated axons in ventral roots does not necessarily contradict the law of Magendie.
Immunocytochemical localization of a methionine‐enkephalin‐resembling neuropeptide in the central nervous system of the american cockroach, Periplaneta americana L
Authors: Verhaert Peter , de Loof Arnold
Published: May 2005

Using the peroxidase antiperoxidase immunocytochemical method, we were able to demonstrate within the brain and retrocerebral complex of Periplaneta americana several neuronal structures which were very specifically stained with an anti‐methionine‐enkephalin antiserum. From the precise localization of this immunoreactive material some speculations about its possible functions could be derived, such as a neurotransmitter‐ or neuromodulatorlike function and/or a neurohormonal role. These data present new evidence for the recently developed concept that opiate peptides, identical or related to those found in higher species, occur also in invertebrates.
Cholinergic amacrine cells in the rat retina
Authors: Voigt Thomas
Published: May 2005

Staining of rat retinal wholemounts with a monoclonal antibody against choline‐acetyl‐transferase (ChAT) reveals two matching populations of amacrine cells in pigmented and albino rat retinae. One population has cell bodies in the inner nuclear layer (INL). Their dendrites are confined to a narrow stratum in the outer half of the inner plexiform layer (IPL). The other, displaced, population has cell bodies in the ganglion cell layer (GCL) withdendrites stratifying in the middle of the IPL. The density changes with eccentricity, ranging from 1,700 cells/mm2 centrally to 600 cells/mm2 in the periphery. Presumptive cholinergic cells were filled withthe fluorescent dye Lucifer yellow. Both subpopulations have the same “starburstlike” morphology as described for rabbit cholinergic amacrine cells (Famiglietti, '83; Tauchi and Masland, '84; Masland et al., '84b). Their dendritic tree sizes change with eccentricity andrange from 160 to 300 μm in diameter. Counterstaining of Lucifer yellow‐filled cells by ChAT immunohistochemistry did not yield an unequivocal double staining. Nevertheless, indirect evidence of same soma size, same numberand form of primary dendrites, same level of stratification, and the good fit into the cholinergic mosaic makes it very likely that the “starburstlike” amacrine cells in the rat use acetylcholine as their transmitter. A comparison with the rabbit cholinergic system strengthens this assumption and reveals a striking similarity between both species.
Neuropeptide‐Like immunoreactive cells in the retina of the larval tiger salamander: Attention to the symmetry of dendritic projections
Authors: Yang Chen‐Yu , Yazulla Stephen
Published: May 2005

Light microscopic immunocytochemistry was used to study the morphology of cells that showed immunoreactivity (IR) to antisera against substance P (SP), glucagon (GLU), met enkephalin (ENK), and somatostatin (SS) in the retina of the larval tiger salamander. Both vertical sections and retinal whole mounts were studied. All four antisera labeled amacrine cells in the inner nuclear layer and cells in the ganglion cell layer (GCL). GLUIR cells had processes stratified throughout the inner plexiform layer (IPL), whereas the other three types had bistratified projections in laminae 1 and 5, withlamina 5 being broader and more dense. Two types of SS‐IR amacrine cell were observed. As seen in retinal whole mount, most GLU‐IR and ENKIR amacrine cells had processes that were symmetrically distributed about the soma, whereas processes of SS‐ and SP‐IR amacrine cells were markedly asymmetrical. The dendritic fields of SP‐IR amacrine cells were selectively oriented toward the periphery of the retina in the nasal, temporal, and dorsal areas. Immunoreactive cells in the GCL had fine projections into the IPL and in addition gave rise to two large oriented processes proximal to the soma that projected in opposite directions for 100–200 μm. The oriented processes often showed further branching; they appeared to be along the radiated lines from the optic disc but did not enter it. The implications of the selectively oriented processes of SP‐IR amacrine cells and cells in the GCL are discussed.
A combined 2‐deoxyglucose and neurophysiological study of primate somatosensory cortex
Authors: Juliano Sharon L. , Whitsel Barry L.
Published: May 2005

The metabolic activity pattern produced in the primary somatosensory cortex (SI) of primates by repetitive delivery of a tactile stimulus is distinctly patchy. The functional significance of these patches, however, remains obscure. This investigation sought to determine the correlation between neural and metabolic activity produced by tactile stimuli and to evaluate the relationship, if any, between the neural activity and metabolic patches evoked by similar stimuli. Experiments were undertaken in which extracellular microelectrode recordings were carried out in animals that subsequently underwent a 2‐deoxyglucose (2DG) study. Three types of relations were identified. First, the receptive fields (RF) and modality properties of neurons sampled in locations at which patches of metabolic label were found matched the “place” and “modal” properties of the stimulus used to produce 2DG labeling. Second, in cortical locations where the RF and modality properties of the sampled neurons differed from either the place or modal properties of the stimulus used to evoke the 2DG label, no above‐background increases in metabolic labeling were found. Finally, in some cortical locations at which the receptive field and modality properties of the neurons matched those of the 2‐deoxyglucose mapping stimulus, no above‐background increases in metabolic labeling were found. This outcome leads us to suggest that moment‐to‐moment changes in neural responsivity, which might remain undetected by conventional receptive field mapping methods, contribute to the patchy pattern of metabolic activity visualized by the 2‐deoxyglucose method.
Association of neuroactive peptides with the protein secretory pathway in identified neurons of Aplysia californica: Immunolocalization of SCPA and SCPB to the contents of dense‐core vesicles and the trans face of the Golgi apparatus
Authors: Reed William , Weiss Klaudiusz R. , Lloyd Philip E. , Kupfermann Irving , Chen Mary , Bailey Craig H.
Published: May 2005

The subcellular distribution of two molluscan neuropeptides, the small cardioactive peptides A and B (SCPA and SCPB), has been determined in two identified Aplysia buccal ganglion neurons, B1 and B2. These neurons were previously shown to synthesize and release these neuropeptides. B1 and B2, identified by their size and location within the ganglion, were labeled by intrasomatic injection of an electron‐dense particulate marker (ferritin or Imposil) permitting the unequivocal identification of their somata and proximal processes in thin sections. The somatic cytoplasm of both neurons had a conspicuous population of large dense‐core vesicles along with a smaller number of compound vesicles and small lucent vesicles. All three vesicle types are found in the neurites within the neuropil and proximal axon in the esophageal nerve. Immunoreactivity was localized on the surface of thin sections by the indirect immunogold method. The primary antiserum was shown to recognize both SCPA and SCPB after the neuropeptides had been immobilized on protein‐coated nitrocellulose membranes by means of glutaraldehyde, the primary fixative used to immobilize SCPA and SCPB in situ. SCP immunoreactivity was present in the lumens of the dense‐core vesicles distributed throughout the cytoplasm of B1 and B2 and in dense‐core regions of the Golgi apparatus in the somatic cytoplasm. Taken together with biochemical evidence that B1 and B2 synthesize and release SCPs, these data suggest that the neuropeptides are sequestered into the protein secretory pathway of B1 and B2, a distribution that supports the notion that the SCPs function physiologically as neurotransmitters or neuromodulators.
Regional and laminar distribution of the dopamine and serotonin innervation in the macaque cerebral cortex: A radioautographic study
Authors: Berger B. , Trottier S. , Verney C. , Gaspar P. , Alvarez C.
Published: May 2005

The regional density and laminar distribution of dopamine (DA) and serotonin (5‐HT) afferents were investigated in the cerebral cortex of cynomolgus monkeys using a radioautographic technique that is based on the high affinity uptake capacity of these aminergic neurons. Large vibratome sections, 50 μm thick, were incubated with [3H] DA (0.2 μM) and desipramine (5 μM) or with unlabeled norepinephrine (5 μM) and [3H] 5‐HT (0.6 μM), which allowed for the specific labeling of the DA and 5‐HT innervations, respectively. After fixation, these sections were dried, defatted, and radioautographed by dipping. Semiquantitative data on the DA innervation also were provided by counting [3H] DA‐labeled axonal varicosities in radioautographs from 4‐μm‐thick sections of the slices obtained after epon embedding.

The DA innervation was widespread and differed in density and laminar distribution in the agranular and granular cortices. DA afferents were densest in the anterior cingulate (area 24) and the motor areas (areas 4, 6, and supplementary motor area [SMA]). In the latter they displayed a trilaminar pattern of distribution, predominating in layers I, IIIa, and V‐VI, with characteristic cluster‐like formations in layer IIIa, especially in the medial part of motor areas. In the granular prefrontal (areas 46, 9, 10, 11, 12), parietal (areas 1, 2, 3, 5, 7), temporal (areas 21, 22), and posterior cingulate (area 23) cortices, DA afferents were less dense and showed a bilaminar pattern of distribution, predominating in the depth of layer I and in layers V‐VI; density in layers II, III, and IV was only 20% of that in layer I. The lowest density was in the visual cortex, particularly in area 17, where the DA afferents were almost restricted to layer I.

The density of 5‐HT innervation was generally greater than that of DA except in the motor areas and in the anterior cingulate cortex. Regionspecific laminar patterns characterized (1) motor areas where a lower density in layer III contrasted with the clusters of DA axons in the same layer; (2) the primary visual cortex (area 17), where two bands of higher density in layers III‐IV and layer V outlined a poorly innervated zone in layer IVc‐β (3) the peristriate area 18, where the 5‐HT network was relatively loose but with a denser band in layer III.

Thus, DA innervation of the cerebral cortex displays major differences between rodents and primates, characterized by expanded cortical targets and by a highly differentiated laminar distribution. This suggests a greater functional importance and a direct role of DA at the cortical level in the control of motor and higher order brain functions.
Morphological identification of the motor neurons innervating the dorsal longitudinal flight muscle of Drosophila melanogaster
Authors: Ikeda Kazuo , Koenig J. H.
Published: May 2005

The dorsal longitudinal flight muscle (DLM) of Drosophila is composed of six muscle fibers (DLM1‐6 from ventral to dorsal) and innervated by five motor neurons (MNs), DLM1‐4 being innervated singly by MN1‐4, and DLM5 and 6 being jointly innervated by MN5. This study identifies and describes the five motor neurons that innervate these six muscle fibers. Horseradish peroxidase (HRP) applied intracellularly to single identified DLM fibers resulted in the labeling of the single motor neuron innervating that muscle fiber by retrograde transsynaptic transport. This method allowed positive identification of the motor neuron innervating a particular muscle fiber, since only the innervating neuron was labeled. The axonal pathway, soma, and dendritic distribution of each labeled motor neuron was traced in the thoracic ganglion, and their relative positions were determined.

The somata of MN1‐4 lie in a cluster located near the lateral surface of the thoracic ganglion at the border of the pro‐ and mesothoracic regions, ipsilateral to the muscle fibers innervated. The somata of MN1 and 2 lie side by side in a horizontal plane with MN1 in a more anterior position. Those of MN3 and 4 lie ventrally to those of MN1 and 2 in a horizontal plane with MN3 in the more anterior position. The soma of MN5 is located contralaterally to the muscle fiber it innervates, lying in the dorsal outermost layer of the thoracic ganglion next to the midline at the border of the pro‐ and mesothoracic regions. In spite of the distant contralateral location of the soma, the dendritic distribution of MN5 occurs in the same area as those of MN1‐4. From these result, these neurons can now be identified in the general ganglionic structure revealed by silver impregnation. The ontogenetic contralateral origin of MN5 and the phylogenetic origin of all five MNs are discussed.
GABA as a potential transmitter in lizard photoreceptors: Immunocytochemical and biochemical evidence
Authors: Engbretson Gustav A. , Anderson Kathy J. , Wu Jang‐Yen
Published: May 2005

The retina of the desert night lizard, Xantusia vigilis, was examined for immunoreactivity to antibodies against γ‐aminobutyric acid and L‐glutamate decarboxylase. At the electron microscopic level it was found that a distinct population of the photoreceptor cells was immunoreactive to both antibodies. Computer‐assisted reconstruction of serial sections positively identified the immunoreactive receptors as cones. These cones constituted 15% of the photoreceptors in the retinal sections, and they were morphologically distinct. The mean diameter of the labeled cone synaptic pedicles was 5.8 μm whereas that of the unlabeled pedicles was 7.9 μm, a statistically significant difference. L‐glutamate decarboxylase was extracted from the lizard brain, positively identified radiometrically, and shown by immuno‐diffusion to crossreact with the antibody used for localization. The authors suggest that the immunoreactive cones synthesize and accumulate γ‐aminobutyric acid. Whether or not it is used by those cones as a neurotransmitter should be tested directly.
Ultrastructure of an identified molluscan neuron in organ culture and cell culture following axotomy
Authors: Berdan R. C. , Hauser G. , Bulloch A. G. M.
Published: May 2005

We examined the ultrastructure of neuron 5 from the buccal ganglion of the mollusc Helisoma trivolvis after axotomy and organ culture, and after isolation of the same neuron in culture. Buccal ganglia containing axotomized neurons 5 were cultured either in host snails or in Leibovitz medium conditioned with ganglia. In addition, some neurons 5 were isolated from buccal ganglia by micro‐dissection and plated into culture. Neuron 5 and its processes were identified in both whole mounts and plastic sections of buccal ganglia after intracellular injection with Lucifer Yellow or horseradish peroxidase. Five days after axotomy of neuron 5, thick sections of buccal ganglia stained with toluidine blue revealed that densely staining basophilic bodies (Nissl bodies) within the cytoplasm had dispersed, i.e., they had undergone chromatolysis. Coincident with chromatolysis was an overall increase in diffuse basophilic staining within the cytoplasm of neuron 5 when maintained in organ culture. The dispersion of Nissl bodies viewed by light microscopy correlated with a more freely arranged rough endoplasmic reticulum and associated polysomes within neuron 5 as seen by electron microscopy. Isolated neurons 5 did not possess densely staining Nissl bodies when examined after 2 days in vitro, thus indicating that chromatolysis occurred earlier in isolated neurons. Furthermore, no increase in diffuse cytoplasmic basophilia was observed within isolated neurons 5 cultured in vitro. However, isolated neurons 5 exhibited a marked increase in the number of lipid‐like bodies (0.5–1.5 μm in diameter) that were particularly evident in scanning electron micrographs. Scanning and transmission electron micrographs revealed that the isolated neurons were free of associated glia, but non‐neuronal cells (hemocytes) would attach themselves to the somata and neurites. Glia surrounding neuron 5 within buccal ganglia exhibited a marked hypertrophy following axotomy and organ culture. Hypertrophy of glia was absent, however, if ganglia were axotomized and left within the animal or axotomized ganglia were implanted into host animals and examined 5 days later by electron microscopy. These observations indicate that, following axotomy, a molluscan neuron may exhibit different morphological features depending on its microenvironment. In addition, the hypertrophy of glia surrounding neurons in Helisoma was not associated with axotomy per se, but with organ culture.
Localization of two calcium binding proteins, calbindin (28 kD) and parvalbumin (12 kD), in the vertebrate retina
Authors: Hamano K. , Kiyama H. , Emson P. C. , Manabe R. , Nakauchi M. , Tohyama M.
Published: May 2005

We used immunocytochemistry to locate two calcium binding proteins, calbindin (CaB) and parvalbumin (PV), in the retina of goldfish, frog, chick, rat, guinea pig, dog, and man. The location of CaB depended on the type of dominant photoreceptor cells in birds and mammals. In cone‐dominant retinas such as those of the chick, CaB‐like immunoreactivity was found in the cones, cone bipolars, and ganglion cells. Amacrine cells 5–12 μm across were also labeled. In rod‐dominant retinas, such as those of the rat, guinea pig, and dog, horizontal cells, small amacrine cells (about 6 μm across), and cells in the ganglion cell layer were labeled. In the human retina, which has both cones and rods in abundance, cones, cone bipolars, ganglion cells, horizontal cells, and small and large amacrine cells were labeled. In the frog and goldfish, the level of CaB‐like immunoreactivity was low. In the frog, a few cones, amacrine cells, and cells in the ganglion cell layer were labeled. No immunoreactive structures were seen in the goldfish retina.

PV‐like immunoreactivity was found in chicks, rats, and dogs. No such immunoreactive structures were seen in the other species. In the chick, only amacrine cells were labeled. In the rat, amacrine cells and several displaced amacrine cells were labeled. In the dog, in addition to amacrine cells and displaced amacrine cells, horizontal cells were strongly labeled. Thus, PV‐like immunoreactivity was found in those elements relating to the modulation of the main pathway of the visual transmission system.
Topographic organization of subcortical projections to the anterior thalamic nuclei in the rat
Authors: Shibata Hideshi
Published: May 2005

Subcortical projections to the anterior thalamic nuclei were studied in the rat, with special reference to projections from the mammillary nuclei, by retrograde and anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase.

The medial mammillary nucleus (MM) projects predominantly ipsilaterally to the entire anterior thalamic nuclei, whereas the lateral mammillary nucleus projects bilaterally to the anterodorsal nucleus (AD) of the anterior thalamic nuclei. A topographic relationship was recognized between the MM and the anterior thalamic nuclei. The dorsal region of the pars mediana of the MM projects to the interanteromedial nucleus (IAM), whereas the ventral region projects to the rostral part of the anteromedial nucleus (AM). The dorsal and the ventral regions of the pars medialis project to the dorsomedial part of the AM at its caudal and rostral levels, respectively. The dorsomedial region of the pars lateralis projects to the ventral AM. The ventrolateral region of the pars lateralis projects to the ventral part of the anteroventral nucleus (AV) in such a manner that rostral cells project rostrally and caudal cells project caudally. The pars basalis projects predominantly ipsilaterally to the dorsolateral AV and bilaterally to the AD. The rostrolateral region of the pars posterior projects to the lateral AV, whereas the medial and the caudal regions of the pars posterior project to the dorsomedial AV.

The rostrodorsal part of the nucleus reticularis thalami was found to project to the anterior thalamic nuclei; cells located rostrally in this part project to the IAM and AM, whereas cells located caudodorsally project to the AV and AD. The laterodorsal tegmental nucleus projects predominantly ipsilaterally to the AV, especially to its dorsolateral part.

The present study demonstrates that subdivisions of the subcortical structures are connected to the subnuclei of the anterior thalamic nuclei, with a clear‐cut topography arranged in the dorsoventral and the rostrocaudal dimensions. © 1992 Wiley‐Liss, Inc.
Cholinergic innervation of the human thalamus: Dual origin and differential nuclear distribution
Authors: Heckers Stephan , Geula Changiz , Mesulam Marek‐Marsel
Published: May 2005

The cholinergic innervation of the human thalamus was studied with antibodies against the enzyme choline acetyltransferase (ChAT) and nerve growth factor receptor (NGFr). Acetylcholinesterase histochemistry was used to delineate nuclear boundaries. All thalamic nuclei displayed ChAT‐positive axons and varicosities. Only the medial habenula contained ChAT‐positive perikarya. Some intralaminar nuclei (central medial, central lateral, and paracentral), the reticular nucleus, midline nuclei (paraventricular and reuniens), some nuclei associated with the limbic system (anterodorsal nucleus and medially situated patches in the mediodorsal nucleus) and the lateral geniculate nucleus displayed the highest density of ChAT‐positive axonal varicosities. The remaining sensory relay nuclei and the nuclei interconnected with the motor and association cortex displayed a lower level of innervation.

Immunoreactivity for NGFr was observed in cholinergic neurons of the basal forebrain but not in cholinergic neurons of the upper brainstem. The contribution of basal forebrain afferents to the cholinergic innervation of the human thalamus was therefore studied with the aid of NGFr‐immunoreactive axonal staining. The anterior intralaminar nuclei, the reticular nucleus, and medially situated patches in the mediodorsal nucleus displayed a substantial number of NGFr‐positive varicose axons, presumably originating in the basal forebrain. Rare NGFr‐positive axonal profiles were also seen in many of the other thalamic nuclei.

These observations suggest that thalamic nuclei affiliated with limbic structures and with the ascending reticular activating system are likely to be under particularly intense cholinergic influence. While the vast majority of thalamic cholinergic input seems to come from the upper brainstem, the intralaminar and reticular nuclei, and especially medially situated patches within the mediodorsal nucleus also appear to receive substantial cholinergic innervation from the basal forebrain. © 1992 Wiley‐Liss, Inc.
Laminar pattern of termination of the ipsilateral cortical projection from SII to SI in cats
Authors: Barbaresi Paolo , Guandalini Paola , Manzoni Tullio
Published: May 2005

The present light and electron microscopic experiments were carried out on the first somatic sensory area (SI) of cats to determine the laminar distribution of axon terminals from the ipsilateral second somatic sensory area (SII) and to identify the types of synapses between these terminals and the neuronal elements of SI. Phaseolus vulgaris‐leucoagglutinin (PHA‐L) was iontophoretically injected into multiple sites and at different cortical depths of the forepaw representation zone of SII. Fixed brain blocks containing the injected SII and ipsilateral SI were cut into slices and processed immunocytochemically to stain PHA‐L‐filled fibers and terminals. Light microscopic examination of SI revealed patches of anterograde labeling in the forepaw representation zone, concentrated mainly in supragranular layers. In these layers, thin immunolabeled fibers branched extensively and formed a dense plexus that was more prominent in layers II and I. Conversely, the infragranular layers contained fragments of vertically oriented thick fibers that rarely emitted axon collaterals. PHA‐L‐labeled axons had numerous swellings along their course, interpreted as boutons en passant, and stalked boutons. Of 19,661 labeled terminals (17,833 beads and 1,828 stalked boutons), 84.74% were obse in supragranular layers, with the highest concentration in layer II(33.15%) and lower in layers I (26.27%) and III (25.30%). The proportion of terminals was lower in layers IV (6.49%) and V (5.45%) and lowest in layer VI (3.32%). These counts also showed that boutons en passant were the majority (90.70%) and stalked boutons, the minority (9.30%). The ratio of these two types of presynaptic specializations was similar (9:1) in all six layers.

Electron microscopic examination of the labeled regions of SI showed that both axon swellings and stalked boutons formed synapses of the asymmetric type with SI neuronal elements. The majority (85.37%) of a sample of 130 labeled terminals synapsed on SI neurons in layers I‐Ill. The identified postsynaptic profiles were dendritic spines (61.11%) or mediumsized and small dendrites (38.89%). These results are discussed in relation to those of a companion study on the laminar pattern of the projection from SI to SII of cats (P. Barbaresi, A. Minelli, and T. Manzoni, 1994, J. Comp. Neurol. 343:582–596). Based on the anatomical organization of these reciprocal connections, there seems to be no clear hierarchicalal relationship between SI and SII in cats. © 1995 Wiley‐Liss, Inc.
Age and sex do not affect the volume, cell numbers, or cell size of the suprachiasmatic nucleus of the rat: An unbiased stereological study
Authors: Madeira M. Dulce , Sousa N. , Santer R. M. , Paula‐Barbosa M. M. , Gundersen H. J. G.
Published: May 2005

The circadian rhythms displayed by numerous biological functions are known to be sex specific and affected by aging. It has not been settled yet whether the sex‐ and age‐related characteristics of circadian rhythms derive from changes in the anatomy of the suprachiasmatic nucleus. To shed light on these issues, we applied unbiased stereological techniques to estimate the volume of the suprachiasmatic nucleus as well as the total number of its cells and the mean volume of their somata and nuclei in progressively older groups of male and female Wistar rats (aged 1, 6, 12, 18, 24, and 30 months). The volume of the nucleus was estimated with the Cavalieri principle on serial sections. The total numbers of neurons and astrocytes were estimated by applying the optical fractionator, and the mean somatic and nuclear volumes of cells were estimated by using isotropic, uniform random sections and the nucleator method. On average, the volume of the suprachiasmatic nucleus was 0.044 mm3, and the total number of neurons and astrocytes was 17,400. Cells of the dorsomedial and ventrolateral components of the nucleus, which are morphologically different, have identical mean perikaryal and nuclear volumes, which we estimated to be 750 μm3 and 400 μm3, respectively.

We further demonstrated that, at all ages analysed, the volume of the suprachiasmatic nucleus, the total cell number, and the mean somatic and nuclear volumes of its cells are affected neither by the age nor by the sex of the animal, regardless of the presence of sex‐ and age‐related variations in circadian rhythms. However, the possibility that females may display changes in the volume of the suprachiasmatic nucleus at older ages cannot be ruled out. No effect of aging was observed in the total number of neurons or in the total number of astrocytes. © 1995 Wiley‐Liss, Inc.
Kinetics of CVD of stoichiometric and Si‐excess SiC in the system MTS/H2 at medium decomposition of MTS
Authors: Josiek Andrei , Langlais Francis
Published: May 2005

For medium decomposition of MTS (10–90 %), at total pressures P < Pt, the growth rate depends fairly strongly on the total flow rate, but is practically independent of P. For P > Pt, the inverse relation holds. In both regions, the growth rate is residence‐time independent, and the apparent activation energy is about 200 kJ/mol. Pt increases with increasing total flow rate, increasing temperature and decreasing initial H2/MTS ratio. For P < Pt, nearly stoichiometric polycrystalline SiC is deposited whereas for P > Pt, nanocrystalline SiC with an important excess of Si grows.