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  • 1
    Digitale Medien
    Digitale Medien
    Spinal cord central canal of the German shepherd dog: Morphological, histological, and ultrastructural considerations (1995)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 224 (1995), S. 205-212 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: This study deals with some macroscopical, microscopical, and ultrastructural aspects of the spinal cord central canal of the German shepherd dog. The caudal end of the spinal cord is constituted by the conus medullaris, which may extend to the first sacral vertebra, the terminal ventricle, and the filum terminale. The latter structure is considered as internum (second to third sacral vertebrae) or externum (fifth caudal vertebra), according to its relation to the dura mater. Occasionally, there is a second anchorage which is close to the level of the sixth caudal vertebra. The central canal is surrounded by a ciliated ependymal epithelium, which differs depending upon the levels. The most caudal part of the filum terminale bears a columnar ciliated ependymal epithelium surrounded by two layers of glia and pia mater, which separate the central canal from the subarachnoid space. Microfil injections show a communication between the cavity and the subarachnoid space, as the plastic is able to pass through the ependymal epithelium. At the level of the terminal ventricle there are real separations of the ependymal epithelium, which seem to connect the lumen of the spinal canal with the subarachnoid space. These structures probably constitute one of the drainage pathways of the cerebrospinal fluid. The diameter of the central canal is related to the age of the animal. However, even in very old animals the spinal cord central canal reaches the tip of the filum terminale and remains patent until death. At the ultrastructural level the ependymal cells present villi, located on cytoplasmic projections, cilia, dense mitochondria, and oval nuclei. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052240209
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Seasonal variation in ovarian histology of the viviparous lizard Sceloporus torquatus torquatus (1995)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 226 (1995), S. 103-119 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Changes in ovarian histology during the reproductive cycle of the viviparous lizard Sceloporus torquatus torquatus are described. In general, the variation in follicular histology observed during the seasonal cycle is similar to that of other lizards. Sceloporus t. torquatus exhibits a cycle in which small, previtellogenic follicles exist in the ovary from December to August. Vitellogenesis occurs between September and November, followed by ovulation from late November to early December. Parturition occurs the following spring. After ovulation, the remaining follicular cells form the corpus luteum and luteolysis did not occur until April-May. Follicular atresia is commonly observed in previtellogenic follicles with polymorphic granulosa, but occurs less frequently in follicles during late vitellogenesis. There are two germinal beds in each ovary. The yolk nucleus is evident in young oocytes as is a vacuolated ooplasma prior to vitellogenesis. Extensive polymorphism is observed in yolk platelets. Mast cells and secretory cells are observed in the thecal layer of the follicular wall as are melanocytes in the ovarian stroma. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052260107
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Trigeminal primary afferent projections to the spinal cord of the frog, Rana ridibunda (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 217 (1993), S. 137-146 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The distribution in the spinal cord of the trigeminal primary projections in the frog Rana ridibunda was studied by means of the anterograde transport of horseradish peroxidase (HRP). Upon entering the medulla via the single trigeminal root, a conspicuous descending tract that reaches the cervical spinal cord segments is established. This projection arises in the ophthalmic (V1), maxillary (V2), and mandibular (V3) trigeminal nerve subdivisions. In the spinal cord, only a minor somatotopic arrangement of the trigeminal fibers was observed, with the fibers arising in V3 terminating somewhat more medially than those from V1 and V2. A dense projection to the medial aspect of the spinal cord, above the central canal, primarily involves V3. Each trigeminal branch sends projections at cervical levels to the contralateral dorsal field, and those from V2 are most abundant. Bilateral experiments with HRP application show convergence of primary trigeminal and spinal afferents within the dorsal field of the spinal cord.The pattern of arrangement of the trigeminal primary afferent fibers in the spinal cord of this frog largely resembles that of amniotes. However, the organization seems simpler and the slight somatotopic distribution of V1, V2, and V3 fibers is similar to the condition in other anamniotes. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052170203
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Epidermal growth factor induces the accumulation of calpactin II on the cell surface during membrane ruffling (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 34-40 
    Details
    ISSN: 0886-1544
    Schlagwort(e): rat liver cells ; immunoprecipitation ; immunocytochemistry ; membrane-bound proteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Confluent and proliferatively quiescent T51B rat liver epithelial cells provide a cellular model for the study of epidermal growth factor (EGF) effects in non-neoplastic cells. Immunoreactive calpactin II, a well-known substrate for EGF-receptor kinase, was found predominantly in the cytosol, although a second im-munoreactive pool was found in a Triton X-100-extractable membrane fraction. Stimulation with EGF resulted in a rapid and transient (2-;5 min) formation of ruffles at the cell surface and at the cell-cell contacts. Both calpactin II and filamentous actin were found co-localized at the membrane ruffles. Immunopre-cipitations of membrane-bound calpactin II from 32P-labeled cells indicate a transient EGF-dependent phosphorylation of calpactin II correlating with membrane ruffling. These results suggest a temporal (2-5 min) function for calpactin II at the plasma membrane during the EGF-induced mitogenesis of T51B cells.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970150106
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Overexpression of an epitope- tagged β-tubulin in Chinese hamster ovary cells causes an increase in endogenous α-tubulin synthesis (1995)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 31 (1995), S. 259-272 
    Details
    ISSN: 0886-1544
    Schlagwort(e): microtubules ; transfection ; hemagglutinin antigen ; autoregulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A Chinese hamster β-tubulin cDNA, engineered to express a 9 amino acid epitope from the influenza hemagglutinin antigen (HA), was transfected into Chinese hamster ovary (CHO) cells. The recombinant protein (HAβ1-tubulin) appeared to behave normally by the following criteria: immunofluorescence indicated that HAβ1-tubulin incorporated into all classes of interphase and spindle microtubules as well as microtubule organizing centers. The sensitivity of the cells expressing HAβ1-tubulin to Colcemid and taxol was unchanged. A 210 kD microtubule associated protein (MAP) remained associated with microtubules that incorporate HAβ1-tubulin. The synthesis of both endogenous β-tubulin and HAβ1-tubulin was repressed by colchicine. The HAβ1-tubulin incorporated into microtubules to the same extent as the endogenous β-tubulin, and the overall extent of microtubule assembly in transfected cells was unchanged. Finally, trasfected cells had normal growth rates and morphologies. When effects on endogenous tubulin production were measured, it was found that expression of the HAβ1-tubulin reduced the synthesis of endogenous wild-type β-tubulin but increased the synthesis of α-tubulin. At steady state, a small increase in total tubulin consistent with the increased synthesis of α-tubulin was found. The results indicate that expression of excess exogenous β-tubulin perturbs the synthesis of endogenous α-tubulin in a manner that is not easily explained by current models of tubulin regulation. The changes in tubulin synthesis along with degradation of excess tubulin subunits may reflect mechanisms that exist to ensure coordinate levels of α- and β-tubulin for assembly. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970310403
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    In vitro migration of Hydra nematocytes: The influence of the natural extracellular matrix (the mesoglea), of collagen type IV and type I, laminin, and fibronectin on cell attachment, migration parameters, and on patterns of cytoskeletal proteins (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 20 (1991), S. 215-227 
    Details
    ISSN: 0886-1544
    Schlagwort(e): cell migration ; extracellular matrix ; cytoskeleton ; nematocytes ; Hydra ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: We have established an in vitro migration system for nematocytes of the fresh water cnidarian Hydra. Nematocytes display a migratory behavior on isolated sheets of the naturally occurring extracellular matrix, the mesoglea, as well as on surfaces coated with collagen type IV or laminin. Cell behavior was analyzed using video microscopic techniques. Average migration speeds of nematocytes on the mesoglea (140 μm/hr) were lower than values reported from in vivo studies (500 μm/hr). Cells on collagen IV moved at about the same average speed (115 μm/hr) as nematocytes on the natural extracellular matrix; those on laminin were considerably slower (20 μm/hr). Attachment but no movement of cells was found on glass or on surfaces coated with collagen type I and fibronectin. In addition to the differential migration speeds, nematocytes displayed distinct morphologies depending on the substratum. In order to elucidate the causes of the observed cell shape and behavior modulations induced by the offered substratum, the arrangement of major cytoskeletal proteins in Hydra nematocytes during the in vitro migration or attachment was investigated. The pattern of F-actin, myosin, and tubulin was determined by immunocytochemical techniques and confocal laser scanning microscopy in nematocytes moving on the mesoglea, on collagen IV, and on laminin, or in cells attaching to fibronectin. We found that the distribution of the cytoskeletal proteins was strikingly different in moving and in stationary cells. The patterns of cytoskeletal proteins in all nematocytes moving on the different substrata, however, was quite similar.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970200305
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Receptor specific for certain nucleotides stimulates inositol phosphate metabolism and Ca2+ fluxes in A431 cells (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 141 (1989), S. 606-617 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: We have recently reported that extracellular ATP induces a transient rise in cytosolic free Ca2+([Ca2+]i) in individual human epidermoid carcinoma A431 cells (Gonzalez et al: Journal of Cellular Physiology 135:269-276, 1988). We have now studied nucleotide specificity and desensitization for several early responses. Extracellular ATP (5-100 μM) caused the rapid formation of inositol trisphosphate and later its metabolites, inositol bisphosphate and inositol monophosphate. ATP also induced the efflux of 45Ca2+ from pre-loaded cells. In addition, an increase in the rate of influx of 45Ca2+ stimulated by extracellular ATP was detected. Based on measurements of 45Ca2+ efflux and influx, desensitization studies, and chlortetracycline fluorimetry, we conclude that ATP mobilizes Ca2+ from internal stores and also stimulates entry across the plasma membrane. These effects were also displayed by UTP and to a lesser extent by ITP, while other nucleoside triphosphates as well as ADP, AMP, and adenosine, were inactive. Furthermore, desensitization of the response to ATP and UTP was seen after prolonged exposure to either nucleotide. This was specific for the nucleotide receptor since a response to bradykinin was not affected by the ATP pretreatment, although pretreatment with phorbol ester inhibited responses to both the nucleotides and bradykinin. Quantitative data on rate of recovery from the desensitized state and the response of desensitized cells to greatly elevated levels of ATP are presented. Extracellular ATP stimulated another early change previously reported for epidermal growth factor, namely, the phosphorylation of an 81-kDa cytoskeletal protein. The stimulation of these events involves an ATP receptor whose properties differ from other ATP receptors that have been described.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041410320
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Secretory character of a group of isoproterenol-induced polypeptides in mouse parotid glands (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 141 (1989), S. 660-666 
    Details
    ISSN: 0021-9541
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The secretory nature of the isoproterenol-induced mouse parotid polypeptides C, D, E, F, and G (molecular weights 64,000, 61,000, 51,500, 38,000, and 37,000, respectively) is documented. Polypeptides C, D, E, F, and G, accumulated in response to successive daily stimulations with isoproterenol, were detected in a fraction enriched in hypertrophic parotid acinar cells. These cells, characterized by an increased content of cytoplasmic granules, maintain a secretory responsiveness to isoproterenol, which has been evidenced by light microscopy, enzymatic analysis, and unidimensional SDS-polyacrylamide gel electrophoresis. Thus, a parallelism in the loss and recovery of both secretory granules, α-amylase and polypeptides C, D, E, F, and G, was observed. Moreover, after secretion stimulation, polypeptides C, D, E, F, and G were detected in the fluid collected directly from parotid gland cannulation. Given the secretory character of polypeptides C, D, E, F, and G, mechanisms explaining both their progressive accumulation along the chronic administration of isoproterenol, as well as their progressive disappearance observed after suspending that treatment, are discussed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcp.1041410326
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  • 9
    Digitale Medien
    Digitale Medien
    mRNA transcription determines the lag period for the induction of pineal melatonin synthesis in the Syrian hamster pineal gland (1990)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 44 (1990), S. 55-60 
    Details
    ISSN: 0730-2312
    Schlagwort(e): actinomycin D ; cycloheximide ; nocturnal melatonin production ; isoproterenol ; β-adrenergic receptors ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: The nocturnal pattern of Syrian hamster pineal melatonin synthesis is characterized by a 6-8 h lag period, followed by a late-night, short-duration peak in both N-acetyltransferase (NAT) activity and melatonin content. Administration of cycloheximide (20 mg/kg body weight) given either at the time of lights out or 4 h into the dark phase to Syrian hamsters blocked the nocturnal increase in both pineal NAT activity and melatonin content. Actinomycin D (5 mg/kg body weight) prevented the nocturnal increase in both constituents only when it was administered at darkness onset, being significantly less effective when injected after 4 h of dark exposure. Reinduction of melatonin production by isoproterenol (2 mg/kg body weight) administration to acutely light-exposed animals during late darkness was prevented by cycloheximide, but not by actinomycin D administration. The results suggest that whereas Syrian hamster pineal melatonin production requires protein synthesis both early and late in the dark phase, the transcription of a putative NAT-related mRNA, which occurs only during the early night, seems to determine the lag period in melatonin synthesis and pineal responsiveness to β-adrenergic receptor agonist stimulation.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcb.240440105
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  • 10
    Digitale Medien
    Digitale Medien
    Preservation of antigenic reactivity after cryofixation, cryosubstitution, and cryoembedding in Lowicryl HM23: Application to alcohol dehydrogenase in Drosophila fat body (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 24 (1993), S. 453-454 
    Details
    ISSN: 1059-910X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jemt.1070240511
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