bluuebunny/crossref_metadata_2025_split huggingface dataset:
Leucine5‐enkephalin afferents to midbrain dopaminergic neurons: Light and electron microscopic examination
Authors: Liang Chang‐Lin , Kozlowski Gerald P. , German Dwight C. 
Published: January 2005

AbstractThe relationship between leucine5‐enkephalin‐containing nerve terminals and midbrain dopaminergic neurons was studied in the adult rat by light and electron microscopy. For light microscopy, alternate midbrain sections were immunostained with rabbit polyclonal antibodies against leucine5‐enkephalin and tyrosine hydroxylase, by means of the peroxidase antiperoxidase technique. Leucine5‐enkephalin stained fibers and terminals were observed with varying density in the retrorubral field (dopaminergic nucleus A8 region), substantia nigra pars compacta (dopaminergic nucleus A9 region), and ventral tegmental area and related nuclei (dopaminergic nucleus A10 region). For electron microscopy, midbrain sections were immunostained with a mouse monoclonal antibody against leucine5‐enkephalin and a rabbit polyclonal antibody against tyrosine hydroxylase, by means of the peroxidase antiperoxidase technique and silver‐intensified colloidal gold reactions, respectively. The nucleus A10 area was examined at the electron microscopic level, and there were (a) both symmetric (75%) and asymmetric (25%) synapses made between leucine5‐enkephalin axon terminals and dopaminergic dendrites, and also synaptic contacts with unlabeled dendrites; (b) leucine5‐enkephalin synaptic contacts with dopaminergic dendrites that were covered with astrocytic membranes; and (c) leucine5‐enkephalin appositions with unlabeled nerve terminals that made synaptic contacts with dopaminergic dendrites, suggestive of axo‐axonic connections. These findings provide the structural basis for both direct and indirect control of A10 dopaminergic neurons by enkephalin‐containing nerve terminals. © 1993 Wiley‐Liss, Inc.
Immunocytochemical analysis of a novel carbohydrate differentiation antigen (CDA‐3C2) associated with olfactory and otic systems during embryogenesis in the rat
Authors: Prouty Stephen M. , Levitt Pat 
Published: January 2005

AbstractCarbohydrate differentiation antigens are known to display specific patterns of expression during mammalian development and are thought to participate in significant morphogenetic events. In the present study, two monoclonal antibodies that react with a novel carbohydrate differentiation antigen (CDA‐3C2) were used to analyze, by light microscopy, the spatiotemporal distribution of this unique high molecular weight antigen during embryogenesis in the rat. Correlative analysis of the development of peripheral neural structures, in which CDA‐3C2 was expressed, was carried out with an anti‐neurofilament antibody. Enzymatic digestion, combined with Western blots, reveal that the CDA‐3C2 epitope is a carbohydrate which is carried on a high molecular weight glycoprotein with a mass of greater than 1 million Daltons. Characteristic of carbohydrate antigens, immunoreactivity was found in several distinct cellular patterns: only along the apical border of cells, along lateral and basal membranes of cells, and extracellular‐like staining in the mesenchyme. During neurulation, CDA‐3C2 showed differential staining in the ectoderm, distinguishing lateral from neural regions. Following closure of the neural tube, there was a striking specificity of expression of CDA‐3C2 in the periphery, found almost exclusively in olfactory and otic epithelial structures. While CDA‐3C2 is found in placode‐derived tissues that subserve sensory transduction, it appears to be primarily associated with the supportive cells (and their secretions) in both otic and olfactory regions and less so with the sensory cells. The data suggest that a unique carbohydrate antigen on a large macromolecule may play a role in neurulation and/or morphogenesis of the placode‐derived otic and olfactory structures. © Wiley‐Liss, Inc.
Developmental study of GnRH neuronal projections to the medial basal hypothalamus of the male Djungarian hamster
Authors: Buchanan Kevin L. , Yellon Steven M. 
Published: January 2005

AbstractThe present study in the male Djungarian hamster determined the neuroanatomical distribution and morphology of gonadotropin‐releasing hormone (GnRH) neurons which innervate the medial basal hypothalamus during sexual maturation. Prepubertal, peripubertal, and postpubertal males were perfused, brains were removed, and crystals of the fluorescent tract tracer, DiI, were implanted directly into the median eminence of the brain. Eight weeks later, brains were sectioned and processed for GnRH immunofluorescence. At all ages, GnRH cell bodies were bipolar or unipolar; both subtypes were labeled with DiI in proportion to their respective numbers in each brain region. GnRH perikarya were distributed in a diffuse ventromedial continuum from the septum through the anterior hypothalamus. In prepubertal males, DiI was present in the majority of GnRH neurons (54% of total) that were located in brain regions rostral to and including the medial preoptic area. In lateral and caudal brain areas, fewer GnRH perikarya contained DiI (28% of total or less). With sexual maturation, fewer GnRH somata were labeled with DiI in areas rostral to the hypothalamus. The data suggest that bipolar and unipolar GnRH neurons in the forebrain, rostral to the preoptic area, are major contributors to the GnRH innervation of the median eminence in the male Djungarian hamster. With the onset of puberty, the finding that decreasing numbers of GnRH perikarya directly project to the medial basal hypothalamus suggests that fewer GnRH neurons constitute the final common pathway that controls gonadotropin secretion. © 1993 Wiley‐Liss, Inc.
The differentiation between neuroglia and connective tissue sheath in insect ganglia revisited: The neural lamella and perineurial sheath cells are absent in a mesodermless mutant of Drosophila
Authors: Edwards John S. , Swales Lesley S. , Bate Michael 
Published: January 2005

AbstractTwo morphogenetic mutations, twist and Delta, that affect the embryonic development of Drosophila in known ways were used to examine the derivation and function of the outer layers of the central nervous system (CNS). Both the extracellular neural lamella, which ensheaths the CNS, and its source, the underlying perineurial sheath cell layer, fail to develop in Drosophila embryos that are homozygous for a loss of function mutation in the twist gene, and which thus lack mesodermal derivatives. The cell layer immediately below the perineurial sheath cells, here termed barrier glial cells, constitute the ion permeability barrier in wild‐type embryos. They are present in twist mutant embryos, appear to be normal at the ultrastructural level, and function as a blood‐brain ion barrier.The apparent derivation of perineurial sheath cells from mesodermal precursors distinguishes them from neurons, glia and other nonneural components of the CNS, such as tracheae, all of which are of ectodermal origin. We confirm Scharrer's interpretation of the relationship between the perineurium and underlying neuroglia.In embryos homozygous for the neurogenic mutant Delta, an embryonic lethal in which excess ventral blastoderm gives rise to neuroblasts, the CNS forms as an amorphous cell mass, with discontinuous perineurial sheath and barrier glial cell layers. We propose that the cell mass is permeable to lanthanum ions and fails to form a blood‐brain barrier because volume growth prevents the formation of continuous surface cell layers. © 1993 Wiley‐Liss, Inc.
Cortical hierarchy reflected in the organization of intrinsic connections in macaque monkey visual cortex
Authors: Amir Y. , Harel M. , Malach Rafael 
Published: January 2005

AbstractNeuronal response properties vary markedly at increasing levels of the cortical hierarchy. At present it is unclear how these variations are reflected in the organization of the intrinsic cortical circuitry. Here we analyze patterns of intrinsic horizontal connections at different hierarchical levels in the visual cortex of the macaque monkey. The connections were studied in tangential sections of flattened cortices, which were injected with the anterograde tracer biocytin. We directly compared the organization of connections in four cortical areas representing four different levels in the cortical hierarchy. The areas were visual areas 1, 2, 4 and Brodman's area 7a (V1, V2, V4 and 7a, respectively). In all areas studied, injections labeled numerous horizontally coursing axons that formed dense halos around the injection sites. Further away, the fibers tended to form separate clusters. Many fibers could be traced along the way from the injection sites to the target clusters.At progressively higher order areas, there was a striking increase in the spread of intrinsic connections: from a measured distance of 2.1 mm in area V1 to 9.0 mm in area 7a. Average interpatch distance also increased from 0.61 mm in area V1 to 1.56 mm in area 7a. In contrast, patch size changed far less at higher order areas, from an average width of 230 m̈M in area V1 to 310 m̈m in area 7a. Analysis of synaptic bouton distribution along axons revealed that average interbouton distance remained constant at 6.4 m̈m (median) in and out of the clusters and in the different cortical areas. Larger injections resulted in a marked increase in the number of labeled patches but only a minor increase in the spread of connections or in patch size.Thus, in line with the more global computational roles proposed for the higher order visual areas, the spread of intrinsic connections is increased with the hierarchy level. On the other hand, the clustered organization of the connections is preserved at higher order areas. These clusters may reflect the existence of cortical modules having blob‐like dimensions throughout macaque monkey visual cortex. © 1993 Wiley‐Liss, Inc.
Ultrastructural analysis of sympathetic neuromuscular junctions on mesenteric veins of the guinea pig
Authors: Klemm M. F. , Van Helden D. F. , Luff S. E. 
Published: January 2005

AbstractThis study reports on the detailed ultrastructure of sympathetic postganglionic varicose axon terminals on mesenteric veins leading from the ileum of the guinea pig and in particular the structural arrangement of the varicosities with venous smooth muscle cells. The response to nerve stimulation in veins has a long time course and it has been suggested that this reflects a wide separation between the site of transmitter release and the receptors on the effector cell membrane. The aim of this study was to determine the distance between individual sympathetic varicosities and smooth muscle cells in mesenteric veins.Fluorescent histochemical preparations of the sympathetic innervation of the different branches of mesenteric veins indicate the branching network of varicose axons around the vessel to be relatively dense. Electron micrographs show the innervation to be confined to the adventitia close to the medio‐adventitial border and to be predominantly catecholaminergic. A serial section ultrastructural analysis of the relationship of the varicosities with the outer smooth muscle cells showed that almost all (98%) of the exposed axon varicosities in the adventitia formed neuromuscular junctions. Three‐dimensional reconstructions from serial sections of individual varicosities have shown that the junctions have structural specialisations identical to neuromuscular junctions described on arterial vessels and similar to those found at skeletal neuromuscular junctions. The density of neuromuscular junctions on the veins was found to be similar to that on the corresponding artery in the same animal.We suggest that in veins, noradrenaline is released focally at neuromuscular junctions. © 1993 Wiley‐Liss, Inc.
Localization of NADPH‐diaphorase in the brain of the chicken
Authors: Brüning Gerold 
Published: January 2005

AbstractNADPH‐diaphorase, an enzyme catalyzed reaction thought to reflect the activity of nitric oxide synthase in the mammalian nervous system, was mapped in the brain of the chicken. Intensely stained neurons and fibers were found in most parts of the telencephalon, in particular in the neostriatum, paleostriatum augmentatum, olfactory tubercle, lobus parolfactorius, hyperstriatum accessorium, and hyperstriatum ventrale. Medial to the nucleus taeniae, an accumulation of stained cells was observed that appeared to merge with a band of stained neurons located dorsal to the occipitomesencephalic tract. These are considered to belong to the nucleus interstitialis of the dorsal olfactory projection. Further caudally, neurons with different staining intensities were found in the lateral hypothalamic area, lateral mammillary nucleus, periventricular organ, ventral tegmental area, medial spiriform nucleus, optic tectum, isthmooptic nucleus, mesencephalic trigeminal nucleus, interpeduncular nucleus, and central gray of the mesencephalon. A particularly dense cluster of NADPH‐diaphorase positive neurons was located in the locus coeruleus. It is proposed that these might represent cholinergic cells intermingled with catecholaminergic neurons, thus forming the avian counterpart of the tegmental cholinergic nuclei of mammals. Several NADPH‐diaphorase reactive neurons were seen in the parabrachial nucleus and medial and dorsal vestibular nucleus, as well as scattered in the reticular formation. In the caudal medulla, intensely stained cells were grouped around the central canal. Therefore the pattern of expression of NADPH‐diaphorase, and thus possibly of nitric oxide synthase, within the avian and mammalian brain might be largely conserved. © 1993 Wiley‐Liss, Inc.
Innervation of the monotreme gastrointestinal tract: A study of peptide and catecholamine distribution
Authors: Keast J. R. 
Published: January 2005

AbstractThe distribution of neurons and endocrine cells containing various peptides or catecholamines was examined in the digestive tracts of the echidna (Tachyglossus aculeatus) and the platypus (Ornithorhynchus anatinus). Comparisons were made with published studies in other species in order to obtain a broader view of the phylogenetic distribution and possible functions of gut peptides and catecholamines. Further comparisons between the echidna and platypus were made in light of their different dietary features and gut histology. The distribution of neurons and axons containing catecholamines or various peptides resembled that in other species (such as the frequent appearance of axons containing substance P and vasoactive intestinal peptide in the intestinal mucosa, and axons containing substance P or enkephalins in the circular muscle). In both species, the stomach histologically resembles the esophagus, being aglandular and lined with stratified squamous epithelium. Innervation of these two organs was similar but not identical, with a greater array of peptides found in the gastric muscle. The intestinal mucosa was densely innervated in both species. The platypus small intestine is unusual in having a thick and deeply folded mucosa (but no villi), in which the superficial epithelium is absent or incomplete at many sites; many axons travel close to these luminal surfaces. Many (putative noradrenergic) axons associated with blood vessels contained neuropeptide Y, but there was no evidence for intrinsic catecholamine‐containing neurons. Somatostatin and cholecystokinin were present in some endocrine cells, but unlike many mammals, absent in neuronal tissue. These studies have shown that there are many strong similarities between monotremes and other mammals in the distribution and array of peptides found within nervous and endocrine tissues of the digestive tract. However, numerous small differences of the echidna and platypus innervation may be correlated with their different digestive structures. © 1993 Wiley‐Liss, Inc.
Neurotransmitters in the nervous system of Macoma balthica (Bivalvia)
Authors: Karhunen Tuula , Airaksinen Matti S. , Tuomisto Leena , Panula Pertti 
Published: January 2005

AbstractThe distribution of histamine‐, octopamine‐, gamma‐aminobutyric acid‐ (GABA) and taurine‐like immunoreactivity in the bivalve mollusc Macoma balthica was studied immunocytochemically with antisera produced in rabbits. Histamine levels in the ganglia and whole animals were also measured by high‐performance liquid chromatography using a postcolumn derivatization method. Immunoreactivity for these substances, except for taurine, is found in the central nervous system of this species. The most extensive neuronal system is revealed with the antiserum against histamine. All the main ganglia contain histamine‐immunoreactive cell bodies, and a dense network of nerve fibers is seen in the ganglia and nerve roots. Histamine‐immunoreactive nerve fibers project to the mantle edge, lips and oesophagus. The basal part of the inhalant siphon is rich in histamine‐immunoreactive fibers. Unlike histamine, octopamine‐ and GABA‐like immunoreactivities are restricted to the central nervous system. Taurine‐like immunoreactivity is not found in the nervous system of this species. In the nervous system, histamine‐immunoreactive cell bodies and fibers are more numerous than those that are octopamine‐ and GABA‐immunoreactive. The distribution of these substance in the ganglia is different. GABA‐immunoreactive cells are typically smaller than most of the histamine‐ and octopamine‐immunoreactive cells. Most GABA‐ and octopamine‐immunoreactive cells and fibers are located in the pedal ganglion. Histamine is distributed more evenly in the ganglia and nerve roots. The biochemical measurements of histamine correlate well with the immunohistochemical findings and confirm the predominant location of the amine in the nervous tissue. These results suggest that histamine is more widespread than some other putative transmitters, and support the concept that histamine may have an important role in many physiological processes in molluscs. © 1993 Wiley‐Liss, Inc.
Distribution and colocalization of choline acetyltransferase immunoreactivity and NADPH diaphorase reactivity in neurons within the medial septum and diagonal band of broca in the rat basal forebrain
Authors: Kitchener P. D. , Diamond J. 
Published: January 2005

AbstractNADPH diaphorase histochemistry and choline acetyltransferase immunocytochemistry were used to assess quantitatively the presence of nitric oxide synthase in the cholinergic neurons ofthe magnocellular basal forebrain complex. Virtually all (97%) NADPH diaphorase reactive magnocellular neurons in the medial septum and the vertical and horizontal limbs of the diagonal band of Broca were choline acetyltransferase immunoreactive, whereas only a proportion ofthe choline acetyltransferase immunoreactive neurons were NADPH diaphorase reactive. Thus NADPH diaphorase histochemistry identified a population ofthe magnocellular cholinergic neurons. Occasionally, NADPH diaphorase reactive neurons were observed within the medial septum and diagonal band of Broca that were not choline acetyltransferase immunoreactive, and in general were morphologically distinct from the magnocellular neurons; such neurons are probably representatives within the medial septum and diagonal band of more widely distributed phenotypically distinct populations of NADPH diaphorase reactive neurons. The proportions of the neurons in which choline acetyltransferase and NADPH diaphorase colocalized in the medial septum and in the diagonal bands of Broca were similar in any one coronal section, but there was a considerable difference in the proportions throughout the rostrocaudal extent oi these nuclei. In the most rostral sections of the medial septum and diagonal band, approximately 70% of the choline acetyltransferase immunoreactive neurons were NADPH diaphorase reactive, whereas the proportion decreased progressively to about 30% at the level ofthe decussation ofthe anterior commissure. To examine further the extent of colocalization throughout the magnocellular basal forebrain complex, sections ofthe magnocellular preoptic nucleus, substantia innominata, and nucleus basalis magnocellularis were examined. While there was little total colocalization of choline acetyltransferase immunoreactivity and NADPH diaphorase reactivity in any particular section (approximately 18%), almost all of the double labelied neurons were in the substantia innominata, with very few in the other nuclei. Thus although there is a caudal to rostral gradient of the proportion of magnocellular cholinergic neurons that are NADPH diaphorase reactive throughout the entire basal forebrain magnocellular complex, subregions, such as the substantia innominata and magnocellular preoptic nucleus, may not follow this trend. The recent demonstration that the NADPH diaphorase histochemical reaction localizes a nitric oxide synthase suggests that attention should be given to the NADPH diaphorase Subpopulation ‐in pathological and experimentally induced alterations of the basal forebrain. © 1993 Wiley‐Liss, Inc.
Retinotopic orgarnzation of the primary visual cortex of flying foxes (Pteropus poliocephalus and pteropus scapulatus)
Authors: Rosa Marcello G. P. , Schmid Leisa M. , Krubitzer Leah A. , Pettigrew John D. 
Published: January 2005

AbstractThe representation of the visual field in the occipital cortex was studied by multiunit recordings in seven flying foxes (Pteropus spp.), anesthetized with thiopentone/N2O and immobilized with pancuronmm bromide. On the basis of its visuotopic organization and architecture, the primary visual area (VI) was distinguished from neighboring areas. Area VI occupies the dorsal surface ofthe occipital pole, as well as most of the tentorial surface of the cortex, the posterior third ofthe mesial surface of the brain, and the upper bank of the posterior portion ofthe spiemai sulcus. In each hemisphere, it contains a precise, visuotopically organized representation of the entire extent of the contnateral visual hrmifield. The representation of the vertical meridian, together with 8–15° of ipsilateral hemifield, forms the anterior border of VI with other visually responsive areas. The representation of the horizontal meridian runs anterolateral to posteromedial, dividing VI so that the lower visual quadrant is represented medially, and the upper quadrant laterally. The total surface area of VI is about 140 mm2 for P. poliocephalus, and 110 Ill∼ for P. scapulattlS. The representation of the central visual field is greatly magnified relative to that ofthe periphery. The cortical magnification factor decreases with increasing eccentricity, following a negative power function. Conoversely, receptive field sizes increase markedly with increasing eecentricity, and therefore the point‐image size is approximately constant throughout VI. The emphasis in the representation of the area centralis m VI is much larger than that expected on the representation of the area flat‐mounted retinas. Thus, a larger degree of convergence occurs at the peripheral representations in the retino‐geniculo‐Gortical pathway, in comparison with the central representations. The marked emphasis in the representation of central vision, the extent of the binocular field of vision, and the relatively large surface area of VI reflect the importance of vision in megachiropterans. © 1993 Wiley‐Liss, Inc.