bluuebunny/crossref_metadata_2025_split huggingface dataset:
Retinal degeneration in the nervous mutant mouse. I. Light microscopic cytopathology and changes in the interphotoreceptor matrix
Authors: LaVail Matthew M. , White Mary P. , Gorrin Gregg M. , Yasumura Douglas , Porrello Kathryn V. , Mullen Richard J. 
Published: January 2005

AbstractNervous is an autosomal recessive mutation in mice (gene symbol, nr) that produces a progressive cerebellar and retinal degeneration. We have examined various cytopathological features of the photoreceptor degeneration by light microscopy. An increase in the number of pyknotic photoreceptor nuclei in the outer nuclear layer (ONL) is first seen at postnatal day (P) 11. Between P13 and P19 there is a rapid loss of photoreceptors, with the ONL about 60% the thickness of littermate controls at P19. Between P19 and 2.5 months of age, photoreceptor cell loss is minimal, and there is a relatively slow loss of these cells between 3 and 7.5 months of age. At 7.5 months, the ONL consists of single row of nuclei, most of which are lost over the ensuing months, although a few photoreceptor nuclei persist at 17 months of age and older. Both rods and cones are lost at comparable rates for the first 2 months of life, but rods are somewhat preferentially lost at later ages. A very slight central‐to‐peripheral gradient of photoreceptor degeneration exists in the nr/nr retina, but no superior‐inferior hemispheric differences are evident. The rate, spatiotemporal gradient, and hemispheric similarity in photoreceptor degeneration are the same in albino nr/nr mice reared either in cyclic light or in the dark, and in pigmented nr/nr mice. Autoradiographic analysis of rod outer segment renewal shows that outer segment membranes are synthesized in nervous homozygotes. Rhythmic outer segment disc shedding and phagocytosis by the retinal pigment epithelium occur at approximately normal rates in nr/nr mice.Histochemical and immunocytochemical study of the interphotoreceptor matrix (IPM) reveals the exclusion of stainable IPM from the outer segment zone by lamellar whorls of outer segment membrane, accumulation of stainable IPM in the basal region of the outer segment zone, and the absence of an intense band of stainable IPM at the apical surface of the retinal pigment epithelium. These changes in the IPM are similar to those seen in the Royal College of Surgeons rat. However, comparison of cytopathological changes in these two mutants reveals that the IPM defect probably is not the primary cause of photoreceptor cell death in nr/nr mice, and that similar phenotypic appearance does not necessarily signify similar pathological processes. © 1993 Wiley‐Liss, Inc.
Collateral sprouting in the electrosensory lateral line lobe of weakly electric teleosts (Gymnotiformes) following ricin ablation
Authors: Lannoo Michael J. , Maler Leonard , Hawkes Richard 
Published: January 2005

AbstractSprouted collateral axons were observed in the electrosensory lateral line lobe (ELL) of gymnotiform teleosts (Apteronotus leptorhynchus:) following the ablation of the supraorbital branch of the anterior lateral line nerve. Ablation was accomplished by using microinjections of the toxic lectin ricin. Sprouted axons were followed for up to 26 weeks postablation. Ricin exposure severely reduced axonal numbers and the peripheral electroreceptors in the region innervated by these fibers. To visualize sprouted fibers, intact lateral line afferent nerve branches were anterogradely labelled with the neuronal tract tracers horseradish peroxidase or cobalt chloride, or the monoclonal antibody Q26A3.Within the four somatotopically organized ELL segments, sprouted collaterals were first observed two weeks after ricin injection in the medial and centromedial segments, and four weeks postinjection in the centrolateral and lateral segments. Sprouting involved intrasegmental, horizontally directed axons from adjacent nerve branch terminal fields, and mixed intra‐and extrasegmental, dorsally directed axons from the ELL deep fiber layer. The sprouting response was robust but variable in its timing, peaking between 6 and 12 weeks. Subsequently, the intrasegmental, horizontally directed fibers were retained but the mixed dorsally directed fibers, including all extrasegmental axons, were retracted. Therefore, this sprouting response appears to consist of a collateral overproduction followed by a selective axonal retraction. In our view, the most likely explanation for this axonal retraction is that the descending inputs from the isthmus and the cerebellum, as well as commissural fibers from the contralateral ELL, maintain established somatotopic relationships by eliminating somatotopically mismatched sprouted collaterals. © 1993 Wiley‐Liss, Inc.
Development of the olfactory organ in the zebrafish, Brachydanio rerio
Authors: Hansen Anne , Zeiske Eckart 
Published: January 2005

AbstractThe development of the olfactory organ of the zebrafish, from the forming of the early placode to the adult organ, was investigated by electron microscopy and DiI labeling. The olfactory placode is formed by a subepidermal layer of cells. These cells differ from those of the epidermis as well as from brain cells, and they do not mingle either with epidermal or with brain cells. No migration of cells from the brain or the epidermis towards the subepidermal cell layer has been observed. The cells of the subepidermal layer seem to form all cell types of the olfactory mucosa, i.e., basal cells, ciliated and microvillous receptor cells, supporting cells, and ciliated nonsensory cells. Axons grow into the forebrain at a very early stage when the epidermis still covers the placode completely. Dendrites grow out when the epidermis separates, building the olfactory pit. This process implicates neither cell lysis nor cell degeneration. The olfactory pit forms a rosette with a midline raphe and olfactory lamellae. The incurrent nostril is separated from the excurrent nostril by a funnel‐shaped structure. Differentiation of the olfactory placode in the embryo is accomplished very quickly, whereas the development into the adult organ during larval stages is a slow process. © 1993 Wiley‐Liss, Inc.
Organization and synaptic connections of cholinergic fibers in the cat superior colliculus
Authors: Jeon Chang‐Jin , Spencer Robert F. , Mize R. Ranney 
Published: January 2005

AbstractThe cat superior colliculus (SC) receives a dense cholinergic input from three brainstem nuclei, the pedunculopontine tegmental nucleus, the lateral dorsal tegmental nucleus, and the parabigeminal nucleus (PBG). The tegmental inputs project densely to the intermediate gray layer (IGL) and sparsely to the superficial layers. The PBG input probably projects only to the superficial layers. In the present study, the morphology of choline acetyltransferase (ChAT)‐immunoreactive axons and synaptic endings in the superficial and deep layers of the SC was examined by light and electron microscopy to determine whether these cholinergic afferents form different types of synapses in the superifical and deep layers.Two types of fibers were found within the zonal (ZL) and upper superficial gray layers (SGL): small diameter fibers with few varicosities and larger diameter fibers with numerous varicosities. Quantitative analysis demonstrated a bimodal distribution of axon diameters, with one peak at approximately 0.3–0.5 μm and the other at 0.9–1.0 μm. On the other hand, ChAT‐immunoreactive fibers in the IGL were almost all small and formed discrete patches within the IGL.Two types of ChAT‐immunoreactive synaptic profiles were observed within the ZL and upper SGL using the electron microscope. The first type consisted of small terminals containing predominantly round synaptic vesicles and forming asymmetric synaptic contacts, mostly on dendrites. The second type was comprised of varicose profiles that also contained round synaptic vesicles. Their synaptic contacts were always symmetric in profile. ChAT‐immunoreactive terminals in the IGL patches contained round or pleomorphic synaptic vescles, and the postsynaptic densities varied from symmetric to asymmetric, including intermediate forms. However, no large varicose profiles were observed.This study suggests that cholinergic fibers include at least two differnt synaptic morphologies: small terminals with asymmetric thickenings and large varicose profiles with symmetric terminals. The large varicose profile in the superficial layers is absent in the IGL. This result suggests that the cholinergic inputs that innervate the superficial layers and the patches in the IGL of the cat SC differ in their synaptic organization and possibly also in their physiological actions. © 1993 Wiley‐Liss, Inc.
Differential expression of N‐ and R‐cadherin in functional neuronal systems and other structures of the developing chicken brain
Authors: Redies Christoph , Engelhart K. , Takeichi M. 
Published: January 2005

AbstractCadherins are a family of cell surface molecules mediating calcium‐dependent cell–cell adhesion in a variety of tissues. More than a dozen cadherins are expressed in the vertebrate brain. To obtain insight into the biological significance of this diversity in cadherin expression, we mapped the expression of N‐and R‐cadherin in the brain of the developing chicken embryo (days 2–19 of incubation) by immunohistochemical and in situ hybridizaiton techniques.Whereas the expression of N‐ and R‐cadherin is relatively uniform or weak in early (about 2–5 days of incubation) and late development (15 days of incubation to hatching stage), these two molecules are differentially expressed in specific nuclei and fiber tracts between days 6–11 of incubation. For example, in the mes‐ and diencephalon, one of the tectofugal pathways and its target nuclei, here called the tecto‐pretecto‐rotundal system, express N‐cadherin. R‐cadherin is expressed by a different tectofugal system, the tectoisthmic pathway. The other tectofugal systems express neither N‐ nor R‐cadherin. In addition, a small number of other mes‐ and diencephalic nuclei express N‐ or R‐cadherin. On the basis of these results and experimental evidence from other studies, we speculate that the two cadherins are involved in the formation and segregation of particular functional systems within the vertebrate central nervous system (CNS) by regulating the formation of nuclei, and the pathfinding and/or the selective fasciculation of neurites.Apart from neuronal elements, a variety of vascular and ependymal structures also express N‐cadherin or R‐cadherin, e.g., the parenchymal blood vessels, the choroid plexus, the floor and roof plates, and the ventricular lining. These findings suggest that the two cadherins play a variety of roles during the development of neuronal and nonneuronal epithelial structures throughout CNS development. © 1993 Wiley‐Liss, Inc.
Neuroanatomical alterations in the rat nucleus of the solitary tract following early maternal NaCl deprivation and subsequent NaCl repletion
Authors: King Camille Tessitore , Hill David L. 
Published: January 2005

AbstractRestricting the NaCl content in the rat maternal and preweaning diet results in a significant and specific reduction (60%) of chorda tympani nerve responsiveness to sodium stimuli in the offspring. Repletion of dietary sodium at any time during postnatal development results in a complete and persistent recovery of chorda tympani nerve function. To learn whether the maturation of postsynaptic cells are also affected by the early dietary manipulation, dendritic morphology, neuronal and glial densities and numbers were studied within the area of the nucleus of the solitary tract (NTS).Examination of dendritic morphologies in Golgi‐Cox stained neurons revealed that cells with multipolar and fusiform somata in the rostral NTS exhibited longer dendrites following dietary NaCl deprivation during development (deprived rats) than in controls. These changes were generally maintained in rats initially deprived of NaCl and then fed a NaCl‐replete diet postweaning (“recovered” rats). In contrast, ovoid neurons were not affected by NaCl deprivation but had increases in the lengths of their dendrites following “recovery” Along with dendritic alterations, the packing density of neurons in the rostral NTS was greater in NaCl‐deprived rats than in controls, but was similar to controls following “recovery” Glial packing density also increased following deprivation and remained high in “recovered” rats.These results indicate that activity‐dependent events as well as events not related to afferent activity (e.g., hormonal changes) may influence the morphological development of NTS neurons. In addition, significant interactions among primary afferent fibers, central neurons, and glia may direct development within the central gustatory system. © 1993 Wiley‐Liss, Inc.
Morphological correlations between spontaneously discharging primary vestibular afferents and vestibular nucleus neurons in the cat
Authors: Sato Fumi , Sasaki Hiroshi 
Published: January 2005

AbstractSynaptic connections between physiologically classified primary vestibular afferents (PVAs) and their target vestibular nucleus (VN) neurons were examined by a combination of intra‐axonal staining and electron microscopic techniques. PVAs originating from the horizontal semicircular canal were electrophysiologically classified as either regular‐ or irregular‐type based on the regularity of their spontaneous discharge patterns, and were intra‐axonally labeled with horseradish peroxidase (HRP). HRP‐labeled PVAs of both types had many swellings along their course that contacted VN neurons. These swellings contained spherical synaptic vesicles and showed asymmetric postsynaptic specialization. Target VN neurons of both types of PVAs were distributed primarily in the superior, medial, and inferior VN. Irregular‐type PVAs made more axosomatic contacts than did regular‐type PVAs. The soma size of target VN neurons and the number of terminal boutons per target VN neuron were larger for irregular‐type PVAs than for regular‐type PVAs. Large VN neurons (presumably kinetic neurons) were innervated exclusively by irregular‐type PVAs. Small VN neurons were innervated by PVAs of the regular‐type and the irregular‐type. These results demonstrate that there is a correlation between the physiological properties and morphological characteristics of PVAs and their target VN neurons. © 1993 Wiley‐Liss, Inc.
Species‐specific patterns of glycoprotein expression in the developing rodent caudoputamen: Association of 5′‐nucleotidase activity with dopamine islands and striosomes in rat, but with extrastriosomal matrix in mouse
Authors: Schoen Siegfried W. , Graybiel Ann M. 
Published: January 2005

AbstractThe glycoprotein 5′‐nucleotidase is a cell surface phosphatase and represents a new marker for striosomes in the adult rat caudoputamen. We report here on its developmental expression in the rat and mouse striatum, and show an unexpected converse 5′‐nucleotidase chemoarchitecture of the caudoputamen in these closely related species.In the rat, 5′‐nucleotidase activity was first visible as neuropil staining in tyrosine hydroxylase‐positive dopamine islands of the midstriatum on postnatal day 1, and by the end of the first postnatal week, 5′‐nucleotidase‐positive dopamine islands also appeared rostrally. This compartmental pattern persisted thereafter, so that in adult animals, in all but the caudal caudoputamen, zones of enhanced 5′‐nucleotidase staining were restricted to calbindin‐D28k‐poor striosomes. Weak 5′‐nucleotidase activity also emerged in the matrix.In striking contrast, in the mouse striatum, enhanced 5′‐nucleotidase activity was preferentially associated with extrastriosomal tissue. Enzymatic reaction first appeared on embryonic day 18, and developed over the first postnatal week into a mosaic pattern in which the matrix was stained but the dopamine islands were unstained. The matrix staining itself was heterogeneous. After the second postnatal week, most of the caudoputamen was stained, and in adult mice only rostral striosomes expressed low 5′‐nucleotidase activity.We conclude that in rats, 5′‐nucleotidase represents one of the few substances that maintains a preferential dopamine island/striosome distribution during striatal development. In mice, 5′‐nucleotidase activity is expressed preferentially in the matrix during development, and its compartmental pattern is gradually lost with maturation, except very rostrally. These findings do not suggest an instructive role of the enzyme in striatal compartment formation in either species, but do suggest the possibility that 5′‐nucleotidase contributes to the differentiation of striatal compartments during development. © 1993 Wiley‐Liss, Inc.
Comparison of the immunocytochemical localization of DARPP‐32 and I‐1 in the amygdala and hippocampus of the rhesus monkey
Authors: Barbas H. , Gustafson E. L. , Greengard P. 
Published: January 2005

AbstractDopamine and adenosine 3′:5′‐monophosphate (cAMP) regulated phosphoprotein of Mr32 kDa (DARPP‐32) and phosphatase inhibitor 1 (I‐1) have been associated with intracellular signal transduction processes and share several biochemical features. Localization of each phosphoprotein in distinct neural structures will aid investigation of their physiologic properties and help identify their unique roles in the nervous system. We have compared the distribution of the two phosphoproteins in the amygdala and hippocampus of the rhesus monkey with the aid of immunocytochemical procedures. Neurons immunoreactive to antibodies raised against the phosphoproteins DARPP‐32 and I‐1 were noted in the cortical, central, and components of the basal group, including the basomedial, the lateral, and to a lesser extent, the basolateral amygdaloid nuclei. Within the large basal nuclei positive neurons were found preferentially in their medial and ventral subdivisions. By making a direct comparison in the same animals, we observed differences in the distribution of the two phosphoproteins in the amygdala. DARPP‐32 and I‐1 positive neurons overlapped partially in the basal nuclei, to a lesser extent in the cortical, but were segregated in the central amygdaloid nucleus with neurons positive for DARPP‐32 noted laterally, and for I‐1 medially.In contrast to the amygdala, where numerous DARPP‐32 and I‐1 positive neurons were observed, only I‐1 had a notable presence in the hippocampus. Moreover, I‐1 associated label was found only in neurons in the granule cell layer of the dentate gyrus, their dendritic plexus, and axons which innervate hilar and CA3 neurons. DARPP‐32 and I‐1 are intracellular messengers associated with signal transduction. Their regional distribution in the amygdala and the hippocampus suggests an involvement in the level of excitability of specific components of these limbic structures. Moreover, our results suggest that I‐1 has a unique role in the intrinsic circuitry of the hippocampal formation and indicate a system where the physiologic properties of I‐1 may be studied in isolation. © 1993 Wiley‐Liss, Inc.
Cortical modules in the posteromedial barrel subfield (Sml) of the mouse
Authors: White Edward L. , Peters Alan 
Published: January 2005

AbstractAn antibody to MAP2 was used on sections through the posteromedial barrel subfield (PMBSF) of primary somatosensory cortex to reveal the distributions of cell bodies and dendrites. It was found that apical dendrites of layer VI neurons form irregular bundles or sheets that break up in layer IV, where most of these dendrites form their terminal tufts. In contrast, the apical dendrites of layer V pyramidal neurons form clusters that ascend into layer II/III where they are joined by apical dendrites of the superficial pyramidal neurons. In layer IV the clusters of the layer V apical dendrites are more concentrated in barrel walls than in hollows. Thus, in layer IV the average center to center spacing between the clusters is about 25 m̈m in the barrel hollows, and about 22 m̈m in the barrel walls. In part, this differential distribution of the apical dendritic clusters is brought about because the apical dendrites of layer V pyramids beneath the periphery of the barrel hollows arc towards the barrel walls as they pass from layer V into layer IV.Based on previous analyses of the three‐dimensional organization of the primary visual areas in the monkey, cat, and rat, it has been proposed that neurons in these cortices are organized into modules that are centered on the clusters of apical dendrites belonging to layer V pyramidal neurons. Mouse PMBSF cortex is composed of similar pyramidal cell modules and the organization of neurons in these modules is similar to that in visual cortex. This suggests that the pyramidal cell modules are fundamental neuronal units that exist throughout the cerebral cortex, and implies that the various functional areas of the cortex in different species are organized according to a common, basic plan. © 1993 Wiley‐Liss, Inc.
Peripheral peptidergic fibers of the trigeminal nerve in the olfactory bulb of the rat
Authors: Finger Thomas E. , Böttger Bärbel 
Published: January 2005

AbstractAxons immunoreactive for calcitonin gene‐related peptide (CGRP) and substance P are present in the olfactory nerve, although few, if any, olfactory receptor cells contain immunocytochemically detectible levels of these peptides. The possible trigeminal origin of these fibers was tested by performing unilateral stereotaxic lesions of the ophthalmic division of the trigeminal nerve, followed 2–25 days later by immunocytochemistry for CGRP and substance P. As reported previously, free nerve endings immunoreactive for both peptides were found transversing the nasal epithelium on the unlesioned side. Also on the unlesioned side, peptidergic axons, immunoreactive for both CGRP and substance P, could be traced from the olfactory nerve into the glomerular layer throughout the olfactory bulb, but especially into its rostral third. Ipsilateral to the trigeminal ganglion lesion, such peptide‐immunoreactive fibers were absent or markedly reduced in the bulb, nerve, and epithelium. These results indicate that the peripheral branches of the ophthalmic branch of the trigeminal nerve enter the olfactory bulb along with the olfactory nerve and terminate in the glomerular layer along with the olfactory axons. Ultrastructural analysis of the CGRP‐immunoreactive terminals in the glomeruli reveal vesicle‐filled axonal processes terminating in the absence of obvious pre‐ or postsynaptic specializations. Whether the trigeminal fibers in the bulb are functional, e.g., convey information to the olfactory bulb via an axon reflex, or relay information from the olfactory bulb to the brainstem trigeminal nuclei is unclear. © 1993 Wiley‐Liss, Inc.
Calbindin D‐28k‐ and substance P‐immunoreactive primary sensory neurons: Peripheral projections in chick hindlimbs
Authors: Duc Christophe , Barakat‐Walter Ibtissam , Droz Bernard 
Published: January 2005

AbstractThe peripheral projections of two distinct subpopulations of primary sensory neurons, expressing either calbindin D‐28k or substance P, were studied in chick hindlimbs by immunodetecting calbindin D‐28k with a rabbit antiserum and substance P with a mouse monoclonal antibody. Calbindin D‐28k‐immunoreactive axons provided an innervation restricted to specific mechanoreceptors such as muscle spindles, Herbst and Merkel corpuscles, or collars of feather follicles but were absent from Golgi tendon organs. In contrast, substance P‐positive axons spread out diffusely in muscles and skin, formed loose plexuses, and extended free branches to the endomysium, arteries, superficial dermis, or dermal pulp of feather follicles.The present results show that calbindin D‐28k‐ and substance P‐immunoreactive primary sensory neurons provide distinct modes of innervation to selective targets in peripheral tissues. The results suggest a possible correlation between CaBP‐expressing nerve endings and rapidly adapting mechanoreceptors. © 1993 Wiley‐Liss, Inc.