bluuebunny/crossref_metadata_2025_split huggingface dataset:
Retinal degeneration in the nervous mutant mouse. II. Electron microscopic analysis
Authors: White Mary P. , Gorrin Gregg M. , Mullen Richard J. , LaVail Matthew M. 
Published: January 2005

AbstractNervous mutant mice (nr/nr) show a rapid loss of most of cerebellar Purkinje cells between the ages of 3 and 7 weeks, as well as a progressive photoreceptor cell degeneration that occurs most rapidly between postnatal days (P) 13 and 19, but with a much slower attrition during the subsequent months. We have carried out an electron microscopic analysis of nr/nr and littermate control mice at representative ages to characterize the subcellular cytopathological changes in this form of retinal degeneration, to gain insight into photoreceptor cell degeneration mechanisms by comparing these changes to those in other rodent forms of retinal degeneration, and to compare the photoreceptor changes with those of cerebellar Purkinje cells.Ultrastructural observations were limited to rod photoreceptors, since the number of cones was limited in our micrographs. The retinas of nr/nr mutant mice can be distinguished from those of normal littermates as early as postnatal day (P) 6. At this time, some of the mitochondria in rod inner segments are larger and more rounded than normal. This represents the earliest cytopathological change thus far observed in this mutant. As early as P9 and thereafter, the volume and integrity of rod outer segment membranes are reduced from normal. In the inner segments of some rod photoreceptor cells, there is a reduction in the volume or number of polyribosomes as early as P11, a reduction in rough endoplasmic reticulum as early as P13, and reduced incidence and less organized Golgi membranes as early as P16. Qualitative evaluation and quantitative stereological analysis show that the enlarged mitochondria in rod inner segments never become normal in shape or size. No changes are seen in the inner retinal layers at any age. Despite similarities with inherited retinal dystrophy in the Royal College of Surgeons rat, as noted in the original description of retinal degeneration in nr/nr mice, ultrastructural features clearly distinguish these mutants. Moreover, nr/nr mice can be distinguished from all other murine forms of retinal degeneration by electron microscopy. © 1993 Wiley‐Liss, Inc.
Input organization of distal and proximal forelimb areas in the monkey primary motor cortex: A retrograde double labeling study
Authors: Tokuno Hironobu , Tanji Jun 
Published: January 2005

AbstractThe present double‐labeling study was designed to demonstrate the morphological framework for motor control in coordinated distal and proximal forelimb movements, which may partly, at least, depend on corticocortical and thalamocortical inputs to the forelimb area in the primary motor cortex. After intracortical microstimulation mapping of the forelimb area in the primary motor cortex of four macaque monkeys, a retrograde tracing study with fluorescent dyes was attempted to label simultaneously neurons in cortical and subcortical sites projecting to the distal forelimb representation area and those projecting to the proximal representation area of the primary motor cortex. Neurons projecting to distal and proximal forelimb parts of the primary motor cortex were largely separate in the following areas: the premotor area, primary somatosensory area, secondary somatosensory area, area 5, and thalamus. In contrast, there was no precise topographic organization of labeled projection neurons in the following areas: the supplementary motor area, cingulate motor area, primary motor cortex adjacent to the injection sites, claustrum, and basal nucleus of Meynert. The present study revealed that the forelimb area of the primary motor cortex receives both segregated and intermixed inputs from cortical and subcortical sources. In particular, the fact that the forelimb area of the primary motor cortex receives topographically organized inputs from the premotor area and nontopographically organized inputs from the supplementary motor area and cingulate motor area indicates possible different functional roles of frontal premotor areas in control of coordinated distal and proximal forelimb movements. © 1993 Wiley‐Liss, Inc.
Hippocampal regulation of the survival and morphological development of locus coeruleus neurons in dissociated cell culture
Authors: Robinson Lisa J. , Black Ira B. , Dreyfus Cheryl F. 
Published: January 2005

AbstractThe influence of traget structure on neural development, originally described for the peripheral nervous system, has more recently been investigated in the central nervous system. We sought to determine whether targets regulate the development of the locus coeruleus, with its diffuse and complex projections in marked contrast to the simpler neural circuits of the peripheral nervous system. Dissociated locus coerules cells were grown alone or with the hippocampus in serum‐free, chemically defined medium that minimized non‐neuronal growth. Coculture with the hippocampus resulted in a significant increase in locus coeruleus tyrosine hydroxylase activity. Elevated tyrosine hydroxylase activity was accompanied by a commensurate increase in the number of tyrosine hydroxylase‐immunoreactive cells, suggesting hippocampal enhancement of locus coeruleus survival. Furthermore, when hippocampal cells were added to locus coeruleus dissociates at zero time, or after two days, tyrosine hydroxylase‐positive cell number was increased only by hippocampal cells added initially, suggesting that the target does indeed foster survival. The apparent target enhancement of locus coeruleus survival seems to be selective since total protein and total neuron number, estimated with neuron‐specific enolase immunocytochemistry, were not affected by the hippocampus. Coculture with the hippocampus also increased the length and complexity of locus coeruleus cell processes. Neither the increase in tyrosine hydroxylase cell number nor the changes in morphology could be attributed to nonspecific effects of the increased cell density in cocultures. Our observations thus suggest that the target hippocampus influences the survival and neurite elaboration of afferent locus coeruleus neurons. © 1993 Wiley‐Liss, Inc.
Quantitative study of primary sensory neurone populations of three species of elasmobranch fish
Authors: Snow Peter J. , Plenderleith Mark B. , Wright Layne L. 
Published: January 2005

AbstractIn order to assess the ability of sharks and rays to sense pain, the proportion of myelinated versus unmyelinated sensory fibres in the dorsal roots and the diameter spectrum of cells in the dorsal root ganglia of three species of elasmobranch fish were ascertained. Electron micrographs were used to count the numbers of myelinated and unmyelinated fibres in montages of whole dorsal roots of the long‐tailed stingray (Himantura sp.), the shovelnose ray (Rhinobatus battilum), and small specimens of the black‐tip shark (Carcharhinus melanopterus). The diameters of dorsal root ganglion cells in each species were measured by using the light microscope. Less than 1% of the dorsal root axons in the long‐tailed stringray and a large specimen of the shovelnose were unmyelinated, whereas in smaller shovelnose rays and in the small black‐tipped sharks, from 14% to 38% of axons were unmyelinated. Unmyelinated fibres differed from those in mammalian nerves in that there was a one‐to‐one association of the fibre with a Schwann cell. We conclude from these observations that myelination was incomplete in the black‐tipped sharks and the smaller specimens of the shovelnose rays. The distribution of the diameter of cells of the dorsal root ganglia of these species was unimodal, resembling the diameter range that has been reported for the somata of myelinated fibres in the cat. We interpret these results as indications that sharks and rays lack the neural apparatus essential for the sensation of pain and we suggest that, to these life forms, the perception of pain might have little relevance to survival. © 1993 Wiley‐Liss, Inc.
Patterns of adrenergic and peptidergic innervation in human olfactory mucosa: Age‐related trends
Authors: Chen Ying , Getchell Thomas V. , Sparks D. Larry , Getchell Marilyn L. 
Published: January 2005

AbstractThe distribution and targets of nerves containing the adrenergic markers tyrosine hydroxylase, dopamine β‐hydroxylase, and neuropeptide Y in the human olfactory mucosa were investigated by immunohistochemistry. Tissue was obtained at autopsy from the nasal cleft of 16 adults ranging in age from 24 to 90 years, and from one spontaneously aborted 16‐week‐old fetus. The presence of olfactory receptor neurons in nasal mucosa was confirmed by staining with the antibody to olfactory marker protein. Targets of adrenergic innervation were blood vessels, including the vasa nervorum within the sheaths of olfactory nerve bundles, and Bowman's glands in the lamina propria. Adrenergic fibers penetrated the adventitia of blood vessels and terminated near the media, and were in close proximity to Bowman's glands but did not enter the acini. In the fetal tissue, the vasa nervorum were the major targets of adrenergic fibers. Age‐related differences in the pattern and statistically significant differences in the density of innervation of blood vessels were noted between adults under and over 60 years of age. In the younger group, plexuses of nerve fibers containing colocalized dopamine β‐hydroxylase and neuropeptide Y occurred adjacent to arterioles and large bundles of fibers adjacent to venules; in older individuals, few fiber plexuses occurred adjacent to arterioles and thin bundles of fibers adjacent to venules. The distribution of adrenergic innervation suggests that vasomotor tone and secretion are regulated by adrenergic nerves. The decrease in adrenergic innervation in older individuals, with resultant effects on perireceptor processes, may be associated with age‐related declines in olfactory function. © 1993 Wiley‐Liss, Inc.
Neuronal morphology and efferent projections of the dorsal nucleus of the lateral lemniscus in the rat
Authors: Bajo Victoria M. , Merchán Miguel A. , López Dolores E. , Rouiller Eric M. 
Published: January 2005

AbstractThe dorsal nucleus of the lateral leminsucs (DLL) is the main source of inhibitory influence in the auditory brainstem of mammals. The cytoarchitecture and connectional properties of DLL were established in the cat in contrast to the rat. The goal of the present study was to establish to what extent the anatomical properties of the rat DLL compare to those of the cat, thus providing a basis of interpretation for future functional studies in the rat, an animal model used more and more in the auditory system.DLL of the rat contains four well‐differentiated neuronal types, as seen in Nissl‐stained material. Type I neurons are large and multipolar with abundant cytoplasm and darkly stained Nissl substance. Type II neurons are large, bipolar and darkly stained in Nissl material. Type III neurons are medium in size and their soma is round or ovoid. Type IV neurons are small and round with scant cytoplasm; they seem to be also the least common neuronal type of the DLL.After Phaseolus vulgaris‐leucoagglutinin or biocytin injections in the DLL, fibers and terminals labeled by orthograde transport were observed in the corresponding region of the contralateral DLL and in the inferior colliculus, bilaterally. A few labeled fibers and terminal fields were seen in the deep layers of the superior colliculus bilaterally, as well as in the medial division of the medial geniculate body and, even more rostrally, in the posterior nucleus of the thalamus. Descending projections from DLL terminated in the periolivary regions of the ipsilateral superior olivary complex.Retrograde tracing based on injections of horseradish peroxidase in the various targets of the DLL confirmed the connections established with orthograde labeling. © 1993 Wiley‐Liss, Inc.
Experimentally induced visual projections to the auditory thalamus in ferrets: Evidence for a W cell pathway
Authors: Roe Anna W. , Garraghty Preston E. , Esguerra Manuel , Sur Mriganka 
Published: January 2005

AbstractWe have previously reported that following specific neonatal brain lesions in ferrets, a retinal projection is induced into the auditory thalamus (Sur et al., Science 242:1437, '88). In these “rewired” ferrets, a novel visual pathway is established through auditory thalamus [the medial geniculate nucleus (MGN)] and primary auditory cortex (A1); cells in both MGN and A1 are visually responsive and exhibit properties similar to those of visual cells in the normal visual pathway.In this paper, we use three approaches—physiological, anatomical, and developmental—to examine which of the retinal ganglion cells project to the MGN in these rewired ferrets. We find that: (1) physiological response properties of postsynaptic visual cells in the MGN are W‐like; (2) retinal ganglion cells back‐filled from the MGN are small and similar to soma sizes of subsets of the normal retinal W cell population; and (3) subpopulations of these small cells can be preferentially rerouted to the MGN in response to different surgical manipulations at birth, consistent with differential W cell projection patterns in normal animals. These data suggest that retinal W cells come to project to the MGN in rewired animals. These findings not only provide a basis on which to interpret functional properties of this novel visual pathway, but also provide important information about the developmental capabilities of specific retinal ganglion cell classes and the regulation of their projections by target structures in the brain during development. © 1993 Wiley‐Liss, Inc.
Immunohistochemical study of catecholamine enzymes and neuropeptide Y (NPY) in the rostral ventrolateral medulla and bulbospinal projection
Authors: Tseng Ching‐Jiunn , Lin Hui‐Ching , Wang Shwun‐De , Tung Che‐Se 
Published: January 2005

AbstractThe purpose of this study was to determine whether neuropeptide Y (NPY) terminals in the intermediolateral spinal cord originate from the rostral ventrolateral medulla (RVLM). Immunohistochemical staining of tyrosine hydroxylase (TH), dopamine‐β‐hydroxylase (DBH), phenylethanolamine‐N‐methyltransferase (PNMT), and NPY in the rat brainstem and spinal cord were performed in this study in order to examine consequences of lesions of the RVLM and of intracisternal injections of 6‐hydroxydopamine (6‐OHDA) on catecholamine and NPY immunoreactivity in the intermediolateral column (IML) of rats. In addition, ricin, a retrograde neurotoxin, was applied in the superior cervical ganglion (SCG) to determine its effect on catecholamine and NPY immunoreactivity in the IML. Computer‐aided image analysis was used to quantify the immunohistochemical changes in the RVLM and spinal cord. The results demosntrated that many catecholamine‐ and NPY‐containing neurons and/or fibers existed in the RVLM and their teminals were found in the IML. After administration of 6‐OHDA intracisternally, the catecholamine and NPY immunoreactivities were decreased both in the brainstem and IML of the spinal cord. Following unilateral microinjection of 6‐OHDA into the RVLM, the number of NPY‐ and catecholamine‐containing neurons decreased and there was a reduction in neuron terminals on the ipsilateral side. After injection of ricin into the SCG, the catecholamine and NPY neurons of the medulla were not affected, whereas their terminals in the IML decreased ipsilaterally. These results indicate that most of the catecholamine‐ and NPY‐immunoreactive terminals found in the IML originated in the RVLM. These terminals appear to project towards the superior cervical ganglia. © 1993 Wiley‐Liss, Inc.
Organization of the nucleus magnocellularis and the nucleus laminaris in the barn owl: Encoding and measuring interaural time differences
Authors: Carr C. E. , Boudreau R. E. 
Published: January 2005

AbstractThe circuit from the cochlear nucleus magnocellularis to the nucleus laminaris supports the encoding and measurement of interaural time differences in the auditory brainstem. Specialization for the encoding of temporal information include the few and/or short dendrites and thick axons of the magnocellular and laminaris neurons, and the high degree of convergence in the circuit.Magnocellular cells have large cell bodies covered with somatic spines. The cells have few dendrites, and the number of dendrites decreases from low to high best frequency regions of the nucleus. Magnocellular neurons receive both auditory nerve terminals and GABAergic terminals with symmetric synapses and terminals filled with pleomorphic vesicles.The axonal projections of magnocellular neurons to the nucleus laminaris form maps of interaural time difference. About 100 magnocellular afferents from each side converge on each laminaris neuron, and the terminals from each side do not occupy separate domains on the cell. These terminals form punctate asymmetric synapses on both the dendrites and the cell bodies of laminaris neurons. Laminaris neurons also receive GABAergic terminals which form symmetric synapses. Laminaris neurons have oval cell bodies covered with very short dendrites. The cells in the low best frequency region of the nucleus laminaris have longer dendrites. © 1993 Wiley‐Liss, Inc.
GABAergic innervation of the rat fascia dentata: A novel type of interneuron in the granule cell layer with extensive axonal arborization in the molecular layer
Authors: Soriano Eduardo , Frotscher Michael 
Published: January 2005

AbstractBy using the combined Golgi/electron microscopy (EM) technique and postembedding immunocytochemistry for gamma‐aminobutyric acid (GABA), we describe a novel type of local circuit neuron in the rat fascia dentata that gives rise to an axon profusely ramifying in the dentate molecular layer. The relatively small ovoid cell body (long axis 12–15 μm) is located directly underneath the granular layer. From both poles of the cell body dendritic processes emerge that enter the molecular layer and hilar region, respectively. The apical dendrites traverse the granular layer, invade the molecular layer, and branch in the same way as granule cell dendrites. Some branches reach the hippocampal fissure. Thus, the apical dendrites of these neurons may receive a similar input pattern as the granule cells. The dendrites are smooth, occasionally bearing varicosities. A few spines are regularly observed. The axon originates from the apical dendrite and traverses the molecular layer horizontally for up to 500 μm. It gives off numerous collaterals that are distributed throughout the entire width of the molecular layer and only rarely enter the granule cell layer. Electron microscopy of the cell body of gold‐toned neurons revealed the well‐known fine‐structural characteristics of nonpyramidal neurons, i.e., an indented nucleus with nuclear inclear inclusions and large aggregations of endoplasmic reticulum. Apical as well as basal dendrites are densely covered with presynaptic boutons, mainly forming asymmetric synapses. The axon terminals of these cells form symmetric synapses with dendritic shafts and, to a lesser extent, with spines. These symmetric synapses, together with the results of our GABA postembedding immunocytochemical study, suggest that this cell is a GABAergic inhibitory neuron that almost exclusively innervates the dentate molecular layer. Together with data from the literature on dentate axoaxonic cells (which innervate the axon initial segments of the granule cells) and GABAergic basket cells (which innervate the granule cell somata and proximal dendrites in the granular layer), the present results indicate that there is a lamination of the GABAergic innervation of the fascia dentata corresponding to the well‐known segregated termination of entorhinal and commissural afferents to this region. © 1993 Wiley‐Liss, Inc.
Sexual dimorphism in the volume of song control nuclei in European starlings: Assessment by a Nissl stain and autoradiography for muscarinic cholinergic receptors
Authors: Bernard Daniel J. , Casto Joseph M. , Ball Gregory F. 
Published: January 2005

AbstractPrevious studies have found that the volume of several song control nuclei is larger in male songbirds than in female songbirds. The degree of this volumetric sex difference within a given species appears to be systematically related to the degree of the behavioral sex difference. The largest volumetric differences have been reported in species in which the male sings and the female sings little, if at all, and the smallest sex differences in volume have been reported in species in which males and females both sing in nearly equal amounts. We compared the volume of three song control nuclei in male and female European starlings (Sturnus vulgaris), a species in which females are known to sing, though at a much lower rate than males. We investigated the volume of hyperstriatum ventrale, pars caudale, nucleus robustus archistriatalis, and area X of the lobus parolfactorius as defined with the use of a Nissl stain. In addition, we measured the volume of area X as defined by the density of muscarinic cholinergic receptors visualized by in vitro receptor autoradiographic methods. The volumes of all three of the song nuclei, as defined by Nissl staining, are significantly larger in males than in females. For area X, Nissl staining and receptor autoradiography indicate the same significant volumetric sex difference. The three nuclei are approximately one and one half to two times larger in males than in females, a degree of dimorphism that is intermediate to those reported for other species. Previous investigations of sex differences in the avian vocal control system have used only Nissl stains to define nuclear volumes. We demonstrate in this paper that receptor autoradiography can be used to assess dimorphisms in nuclear volume. Broad application of this approach to a number of neurotransmitter receptor systems will better characterize the dimorphisms in the song system, and therefore will provide greater insight into the neuroanatomical and neurochemical control of birdsong. © 1993 Wiley‐Liss, Inc.