bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of retinal amacrine cells in the mouse embryo: Evidence for two modes of formation
Authors: Hinds James W. , Hinds Patricia L. 
Published: December 2004

AbstractDeveloping amacrine and ganglion cells have been graphically reconstructed from a series of 567 consecutive thin sections of the E17 mouse retina on the first day when an obvious inner plexiform layer (IPL) is present and 2 days later than for our previous study of amacrine cell formation at E15 (Hinds and Hinds ('78). At E17 amacrine cells of the neuroblastic layer (normally placed amacrine cells), unlike those at E15, appear to develop directly from ventricular cells; intermediate elements are bipolar‐shaped cells with terminal arborization in the IPL. On the other hand, the development of displaced amacrine cells and some normally placed amacrine cells at E17 appears to closely resembles that described for all amacrine cells at E15: derivation from “ganglion cells” by loss of the axon and transformation of the cell. Three lines of evidence support this conclusion. (1) Cells have been found that resemble ganglion cells except that they have only an apparent axon remnant and have somata restricted to the IPL and the immediately adjacent portion of the ganglion cell layer (GCL); amacrine cells transitional between these cells and the smaller and darker, normally placed amacrine cells also occur in the IPL. (2) Axons of two ganglion cells have been found which appeared to be in the process of breaking up and degenerating. (3) The fraction of anaxonic cells with somata in the GCL (two out of 79, or 3%) or in the GCL plus IPL (ten out of 88 or 11%) is too small to account easily for the large fraction (probably at least 45%) of displaced amacrine cells found in the adult, even with conservative assumptions (P < 0.05). A mathematical model suggests that approximately 40% of the ganglion cells present at E17 will lose their axon, and of these around half will migrate to the neuroblastic layer, while the other half will become displaced amacrine cells. The results suggest a natural explanation for the recent finding that wide field amacrine cells are found with somata on both sides of the IPL, while narrow field amacrine cells are never displaced: the former may be derived from ganglion cells by loss of the axon, while the latter may be formed directly from ventricular cells.
Location and distribution of tracheosyringeal motorneuron somata in the fowl
Authors: Youngren Orlan M. , Philips Richard E. 
Published: December 2004

AbstractInjection of horseradish peroxidase solution (HRP) into the tracheosyringeal musculature and tongue of the domestic chick labeled their motorneuron somata inthe medulla. Those of tracheosyringeal motor neurons occupied the caudal portions of the nucleus nervi hypoglossi (n. XII), whereas those for motor neurons supplying the tongue occupied the rostral part. The rostrocaudal representations of tracheolateralis, sternotrachealis, and ypsilotrachealis muscles were roughly mapped by the rostrocaudal distribution of labeled somata in n. XII. Except for sparse labeling found in the caudal part of the dorsal vagal nucleus of a few animals, no labeled cells were found outside of n XII. Most tracheosyringeal injections labeled contralateral n. XII, but section of the contralteral tracheosyringeal nerve high on the neck prior to HRP injection abolished this labeling.
Structure of the piriform cortex of the opossum. I. Description of neuron types with golgi methods
Authors: Haberly Lewis B. 
Published: December 2004

AbstractThe piriform cortex was studied in the adult opossum with rapid Golgi and Golgi‐Cox techniques.Most pyramidal cells in the deep part of layer II and layer III resemble those in other parts of the cerebral cortex by virtue of a single apical dendritic trunk, multiple basal dendrites, a large number of small to medium dendritic spines, and a deeply directed axon. Pyramidal cells in the superficial part of layer II are similar with the exception that “secondary” apical dendrites often emerge directly from the cell body rather than from a single primary trunk.With conservative criteria for categorization, nine different types of nonpyramidal cells were distinguished, four of which have not been previously described. Layer I contains a small number of neurons with both smooth and spiny dendrites including distinctive fusiform cells with large somatic appendages. As in other species, the most common type of nonpyramidal neuron in layer II is the semilunar cell which has only apically directed dendrites. These cells have distinctive large spines confined to their distal dendritic segments. The mid to deep portion of layer III contains multipolar neurons with smooth dendrites that resemble the well‐known large stellate cells in neocortex. In addition, layer III contains three non‐pyramidal neuron types with spiny dendrites: (1) fusiform and multipolar cells with complex, branched dendritic appendages and somatic spines, (2) very large multipolar cells (up to 35 μm mean diameter) with large‐diameter dendrites that give rise to abruptly tapering side branches and filiform spines, and (3) multipolar cells with profusely spiny dendrites. In all three layers, small neurons have been found with spherical cell bodies and “axoniform” dendrites that resemble the so called neurogliaform neurons described in a variety of brain areas. A striking feature of the organization of the piriform cortex is that, with the exception of the neurogliaform neurons, the different types of nonpyramidal cells tend to be segregated in individual layers or sublayers.Physiological implications of the results are discussed. Remarks are also made concerning the potential of the piriform cortex as a model cortical system.
Structure and innervation of the inner ear of the bowfin, Amia calva
Authors: Popper Arthur N. , Northcutt R. Glenn 
Published: December 2004

AbstractThe hair cell orientation patterns and the number of innervating nerve cells was determined for the ear of the holostean fish Amia calva. Scanning electron microscopy was used to analyze the sensory cells of the three otolith organs: the saccule, the lagena, and the utricle. The utricular hair cell orientation pattern is similar to that found in most vertebrates, while the lagenar hair cell pattern is similar to that in ostariophysine fishes. The saccule has both horizontally and vertically oriented hair cells, although in the living animal many of the horizontally oriented cells are really oriented lateromedially. The transition region between cells oriented horizontally and vertically suggests that the horizontal cells are ontogenetically derived from vertically oriented cells. The lagenar macula has the largest sensory region, with over 216,000 cells in its main sensory part. The utricular macula contains over 56,400 cells in the main sensory region, and the saccular macula over 8,600 cells. The otic nerve divides into anterior and posterior rami, and ganglion cell counts totaled 2,021 in the anterior ramus and 1,619 in the posterior ramus. There are three populations of ganglion cells in each ramus, on the basis of differences in cell diameter. By a rough estimate, the ratio of sensory to ganglion cells is at least 90:1. By comparing SEM data from Amia, other nonteleosts, and various teleost species, we suggest that the ontogenetic derivations of the horizontal cells in the teleosts and nonteleosts are substantially different and apparently unrelated to each other and that the most primitive ray‐finned fishes had only vertically oriented sensory cells while the horizontally oriented cells subsequently evolved at least twice, once in Amia and other nonteleosts, and once in the ancestors of the teleosts.
Morphology of normal and deafferented neurons in the chick ectomamillary nucleus
Authors: Peduzzi J. D. , Crossland W. J. 
Published: December 2004

AbstractNeurons in the ectomamillary nucleus (EMN) undergo both atrophy and cell death following eye removal at hatching. It is not known whether all EMN neurons are affected uniformly by transneuronal atrophy or whether cell loss is an artifact due to misidentification of atrophied neurons as glia.In a preliminary morphological study, four types of neurons were found in the EMN by using the rapid Golgi method: A large multipolar neuron (type I); two medium‐sized spindle‐shaped neurons, one possessing many dendritic branches (type II) and the other possessing few dendritic branches (type III); and a small round neuron (type IV). Horseradish peroxidase (HRP) was then injected into two of the EMN projection fields in enucleated chicks in order to label retrogradely as many EMN neurons as possible. Types, I, II, and III neurons were identified both in the control and experimental EMN. The three types of backfilled neurons showed different degrees of transneuronal atrophy ranging from 12 to 47%. The type IV neuron, which could not be backfilled, was inferred to atrophy by 33%. Substantial differences in transneuronal atrophy, therefore, exist among the different types of neurons within the same nucleus.Since no glialike neurons could be retrogradely labeled it was concluded that there is a true neuron loss in the EMN following eye removal rather than mistaken identification of neurons as glia.
The development of the Purkinje cell in the cerebellar cortex of the opossum
Authors: Laxson L. C. , King J. S. 
Published: December 2004

AbstractThe development of the Purkinje cell in the cerebellar cortex of the opossum, Didelphis virginiana, was analyzed by using Golgi preparations and electron microscopy. The maturation process of the Purkinje cell was observed to occur in five stages: the immature stage, the perisomatic den‐drite stage, the perisomatic spine stage, the main dendrite stage, and the adult stage. These stages were first defined by Hendelman and Aggerwal (′80), using Golgi preparations of immature mouse cerebellum.Each of the five stages of Purkinje cell development, as observed in electron micrographs, is characterized by distinct synaptic relationships and cytological features. During the first or immature stage (postnatal (PN) 19‐32), the Purkinje cells have long apical processes which may be involved in the early migration of these neurons. Few boutons make synaptic contacts with Purkinje cells during the early part of this first stage; synapses are more frequent by the end of the immature stage. The second or perisomatic dendrite stage (PN 33‐44) is characterized by numerous somatic processes which have the cytological characteristics of dendrites. All synaptic contacts present during this stage form asymmetric contacts and contain round vesicles. The shape of the terminals and their postsynaptic location were used to tentatively distinguish different types of terminals. During the third or perisomatic spine stage (PN 45‐60) the Purkinje cell has numerous somatic spines and the dendritic tree is achieving its mature form. Most synaptic terminals observed during this period have asymmetric junctions and contain spherical vesicles; both the perisomatic spines and the dendritic shafts and spines are the postsynaptic sites of these terminals. Another type of bouton has pleomorphic vesicles and forms indistinct symmetric junctions directly on the cell body. The fourth stage, the main dendrite stage (PN 61‐77), is characterized by the loss of the perisomatic spines. Terminals on the soma contain pleomorphic vesicles and form symmetric synapses. The thorns of the primary and secondary dendrites and the more distal dendritic spines are postsynaptic to boutons with spherical vesicles and asymmetric junctions. The adult stage or the mature stage (PN 78‐adult) is characterized by the appearance of adult synaptic relationships.These data suggest that although olivary axons are present in the cerebellum by PN 14 (King et al., ′82), synaptogenesis does not ensue until the latter part of the immature stage (PN 26‐32). During the subsequent stages of Purkinje cell development, synaptic formation and remodeling proceeds until the adult structure and synaptic relationships are achieved about PN 78–80.
Astrocytes and neurons regulate the expression of the neural recognition molecule janusin by cultured oligodendrocytes
Authors: Jung Marion , Pesheva Penka , Schachner Melitta , Trotter Jacqueline 
Published: December 2004

AbstractJanusin (formerly designated J1–160/180) is an extracellular matrix glycoprotein highly homologous to tenascin, consisting of two major molecular forms of 160 and 180 kD expressed by oligodendrocytes and in myelin. Janusin expression is upregulated during myelination and in the adult it remains expressed at lower levels. It is also present at the node of Ranvier, where myelin, axon, and astrocytic process are in close contact. To gain an understanding of the regulatory mechanisms which may under‐lie expression of janusin, the differentiation stage‐dependent expression of janusin was studied in cultures enriched in mouse oligodendrocytes and their precursor cells. Expression of janusin by these cells was highest on both A2B5+ and O4+/O1− oligodendroglial precursor cells and a subset of myelin associated glycoprotein‐positive (MAG+) oligodendrocytes. Hardly any of the more differentiated O1+ or O10+ oligodendrocytes expressed janusin. Expression of janusin was influenced by co‐culture with astrocytes or neurons. Astrocytes or astrocytic‐conditioned culture supernatants elevated the expression of janusin by the more differentiated oligodendrocytes (O1+ or MAG+ cells), while its expression by oligodendroglial precursor cells was relatively unchanged. Platelet‐derived growth factor, but not basic fibroblast growth factor, also elevated the expression of janusin by O1+ or O10+ oligodendrocytes. In contrast, co‐culture with neurons originating from dorsal root ganglia or spinal cord decreased the expression of cell‐bound janusin by oligodendrocytes and their precursor cells. These observations indicate that expression of janusin on these cells in culture is susceptible to opposing regulatory influences from astrocytes and neurons. Such influences may modulate the temporal and spatial distribution of janusin in the developing and adult central nervous system. © 1993 Wiley‐Liss, Inc.
Transient presence of GABA in astrocytes of the developing optic nerve
Authors: Ochi Satoko , Lim Jae Y. , Rand Mark N. , During Matthew J. , Sakatani Kaoru , Kocsis Jeffery D. 
Published: December 2004

AbstractImmunostaining and high‐pressure liquid chromatography (HPLC) were used to study the developmental time course of astrocytic γ‐aminobutyric acid (GABA) expression in rat optic nerve. GABA immunostaining was carried out on cultured astrocytes, and on whole optic nerve. Confocal scanning laser microscopy was used to obtain optical sections in excised whole tissue in order to localize the cellular origins of GABA within the relatively intact optic nerve. GABA immunoreactivity was localized in astrocytes identified by GFAP staining; GABA staining was most intense in early neonatal optic nerve and attenuated over 3 weeks of postnatal development. The staining was pronounced in the astrocyte cell bodies and processes but not in the nucleus. There was a paucity of GABA immunoreactivity by postnatal day 20, both in culture and in whole optic nerve. A biochemical assay for optic nerve GABA using HPLC indicated a relatively high concentration of GABA in the neonate, which rapidly attenuated over the first 3 postnatal weeks. Immunoreactivity for the GABA synthesis enzyme glutamic acid decarboxylase (GAD) was pronounced in neonates but also attenuated with development. These results indicate that GABA and the GABA synthesis enzyme GAD are localized in astrocytes of optic nerve, and that their expression is transient during postnatal development. © 1993 Wiley‐Liss, Inc.
Single ion channel currents in neuropile glial cells of the leech central nervous system
Authors: Müller Michael , Hanke Wolfgang , Schlue Wolf‐R. 
Published: December 2004

AbstractThe patch‐clamp technique was used to investigate the activity of single ion channels in neuropile glial (NG) cells in the central nervous system (CNS) of the medicinal leech, Hirudo medicinalis. We found evidence for two distinct Cl− channels that could be distinguished by their basic electrical properties and their responses to different inhibitors on single ion channels currents. In the Inside‐out configuration in symmetrical Cl solutions, these channels showed current‐voltage relationships with slight outward rectification, mean conductances of 70 and 80 pS, and reversal potentials near 0 mV. Significant permeability to Na+, K+, or SO42− could not be detected. The open‐state probability of the 70 pS Cl− channel increased with membrane depolarization, whereas the open‐state probability of the 80 pS Cl− channel was voltage‐independent. The application of the stilbene derivative DIDS (100 μM) to the cytoplasmic side of the glial cell membrane blocked both Cl− channels. The activity of the 70 pS channel was blocked irreversibly by DIDS, whereas the activity of the 80 pS channel reappeared after wash‐out of DIDS. Both channels were blocked reversibly by 1 mM Zn2+. K+ channels could only be observed occasionally in the soma membrane of the NG cells. We have characterized a 60 pS K+ channel with a high selectivity for K+ over Na+. The low density of K+ channels in the soma membrane may indicate a non‐uniform distribution of this channel type in NG cells. © 1993 Wiley‐Liss, Inc.
Peptide receptors in astroglia: Focus on angiotensin II and atrial natriuretic peptide
Authors: Sumners Colin , Tang Wei , Paulding Waltke , Raizada Mohan K. 
Published: December 2004

AbstractAstroglial cells derived from the mammalian central nervous system contain a wide variety of peptide receptors, including specific sites for angiotensin II (AII) and atrial natriuretic peptide (ANP). The AII receptors present in these cells are primarily of the AT1 subtype. The ANP receptors present in these cells consist of a mix of ANP‐A and ANP‐B sites (“biological receptors”) and also ANP‐C sites (“clearance receptors”). Available evidence indicates that activation of AII receptors results in a stimulation of astroglial proliferation, whereas ANP has an antiproliferative effect in these cells. Intracellular pathways which may mediate these effects of AII and ANP on cell proliferation are discussed, including the presentation of novel data on the activation of protein kinase C and of glucose uptake by AII. We also consider the possibility that the opposing actions of AII and ANP on astroglial proliferation may represent another facet of the mutual antagonism between these two peptides, which has been observed throughout mammalian systems. © 1994 Wiley‐Liss, Inc.
Voltage‐dependent ion channels in glial cells
Authors: Sontheimer Harald 
Published: December 2004

AbstractGlial cells, although non‐excitable, express a wealth of voltage‐activated ion channels that are typically characteristic of excitable cells. Since these channels are also observed in acutely isolated cells and in brain slices, they have to be considered functional in the intact brain. Numerous studies over the past 10 years have yielded detailed characterizations of glial channels permitting comparison of their properties to those of their neuronal counterparts. While for the most part such comparisons have demonstrated a high degree of similarity, they also provide evidence for the expression of some uniquely glial ion channels. An increasing number of studies indicate that the expression of “glial” channels is influenced by the cells' microenvironment. For example, the presence of neurons can induce or inhibit (depending on the preparation and type of channel studied) the expression of glial ion channels. Like ion channels in excitable cells, glial channels can be functionally regulated by activation of second‐messenger pathways, allowing for short‐term modulation of their membrane properties. Although the extent to which most of the characterized ion channels are involved in glial function is presently unclear, a growing body of data suggests that certain channels play an active role in glial function. Thus inwardly rectifying K+ channels in concert with delayed rectifying K+ channels are thought to be involved in the removal and redistribution of excess K+ in the brain, a process referred to as “spatial buffering.” Glial K+ channels may also be crucial in modulating glial proliferation. Cl− channels and stretch‐activated cation channels are believed to be involved in volume regulation. Na+ channels appear to be important in fueling the glial Na+/K+ ‐pump, and Ca2+ channels are likely involved in numerous cellular events in which intracellular Ca2+ is a critical second messenger. © 1994 Wiley‐Liss, Inc.
Glutamate‐induced calcium signaling in astrocytes
Authors: Kim Warren T. , Rioult Marika G. , Cornell‐Bell Ann H. 
Published: December 2004

AbstractAstrocytes respond to the excitatory neurotransmitter glutamate with dynamic spatio‐temporal changes in intracellular calcium [Ca2+]i. Although they share a common wave‐like appearance, the different [Ca2+]i changes‐‐an initial spike, sustained elevation, oscillatory intracellular waves, and regenerative intercellular waves‐‐are actually separate and distinct phenomena. These separate components of the astrocytic Ca2+ response appear to be generated by two different signal transduction pathways. The metabotropic response evokes an initial spatial Ca2+ spike that can propagate rapidly from cell to cell and appears to involve IP3. The metabotropic response can also produce oscillatory intracellular waves of various amplitudes and frequencies that propagate within cells and are sustained only in the presence of external Ca2+. The ionotropic response, however, evokes a sustained elevation in [Ca2+]i associated with receptor‐mediated Na+ and Ca2+ influx, depolarization, and voltage‐dependent Ca2+ influx. In addition, the ionotropic response can lead to regenerative intercellular waves that propagate smoothly and nondecrementally from cell to cell, possibly involving Na+/Ca2+ exchange. All these astrocytic [Ca2+]i changes tend to appear wave‐like, traveling from region to region as a transient rise in [Ca2+]i. Nevertheless, as our understanding of the cellular events that underlie these [Ca2+]i changes grows, it becomes increasingly clear that glutamate‐induced Ca2+ signaling is a composite of separate and distinct phenomena, which may be distinguished not based on appearance alone, but rather on their underlying mechanisms. © 1994 Wiley‐Liss, Inc.
Über zwei isomere Formen des 5‐(2,4‐Dinitroanilino)‐2‐methyl‐benzimidazols
Authors: Stäuble Max 
Published: December 2004

Abstract1. 5‐(2,4‐Dinitroanilino)‐2‐methyl‐benzimidazo1 besitzt Dipolcharakter und zeigt normalerweise den Smp. 156° (I). Die Verbindung krystallisiert aus Wasser oder wässrigem Alkohol ohne Krystallwasser.
Über die katalytische Herstellung von 1,4‐Naphthochinon aus Naphthalin
Authors: Fierz‐David H. E. , Blangey L. , v. Krannichfeldt W. 
Published: December 2004

Abstract1. Bei der katalytischen Oxydation von Naphthalin über einem mit Kaliumsulfat stabilisierten Vanadiumpentoxyd‐Katalysator wurde bei einer Reaktionstemperatur von 430° und einem Naphthalin‐Luftverhältnis von 1 : 40 1,4‐Naphthochinon in einer Ausbeute von 15% der Theorie erhalten.