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  • Cell & Developmental Biology  (656)
  • EARTH RESOURCES AND REMOTE SENSING  (560)
  • 2010-2014
  • 1980-1984  (1.185)
  • 1925-1929  (31)
  • 1984  (1.185)
  • 1927  (31)
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  • 2010-2014
  • 1980-1984  (1.185)
  • 1925-1929  (31)
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  • 1
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 129-135 
    ISSN: 0886-1544
    Schlagwort(e): amoeboid motion ; chemoattractants ; chemotaxis ; Dictyostelium ; filopodia ; folic acid ; pterins ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Living vegetative D. discoideum amoebae were studied to determine whether their filopodia respond to folic acid, a chemoattractant for these cells. Exponentially growing amoebae (ca. 10 μm diameter) exhibit 5-30 μm long filopodia; at stationary phase, aggregation competent amoebae have numerous multibranched filopodia up to 100 μm long. Folic acid was observed to stimulate production, elongation, and branching of filopodia with its effects progressively changing as the amoebae approach aggregation. Filopodial construction was also found to be dependent upon Mg2+ levels. The significance of these results is discussed with respect to progressive changes within the vegetative phase as well as to the mechanisms of amoeboid movement, pseudopodial activity, and chemotaxis.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 1-5 
    ISSN: 0886-1544
    Schlagwort(e): motility ; power output ; muscle ; flagella ; cytokinetic furrow ; mitotic spindle ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Cellular motile systems as diverse as muscle and the mitotic spindle have been compared by their specific power output: the maximum power they develop per unit of engine volume. Striated muscles and flagella have high specific output; their performance is comparable to that of typical automobile engines. The cytokinetic furrow and the mitotic spindle have very much lower specific power output. The furrow's output is 7,000 times lower than muscle and the spindle's is 300,000 times lower. Different macromolecules have been used to generate power in systems with similar output (muscles and flagella) and, conversely, the same macromolecular motor has been used in systems with very different output (muscles and cytokinetic furrows). The common feature amid this diversity is adaptation to a particular biological role, which specific power output reflects very well. High values are found where a powerful, compact engine should be advantageous, while low values are found where precision, not power, matters most.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 76-76 
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 431-441 
    ISSN: 0886-1544
    Schlagwort(e): dynein ; chromatophores ; permeabilization ; melanosomes ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Teleost chromatophores are filled with individual pigment granules that rapidly aggregate to the cell center or become dispersed throughout the cytoplasm in response to environmental stimuli. Microtubules appear to be required for pigment aggregation (movement toward the cell center), and recent findings have suggested that a dynein-like ATPase may participate in force production. Based on previous studies, however, it has been argued that pigment aggregation does not require energy directly, a view that supports the involvement of an elastic component in granule movement. To examine this point further, we have reinvestigated the energy requirements for pigment aggregation using both intact cells and detergent-permeabilized cell models of Fundulus melanophores. Poisons of oxidative phosphorylation, namely, 2,4 dinitrophenol and NaCN, reversibly inhibit melanosome aggregation in response to adrenaline. Inhibition of movement results directly from depletion of intracellular ATP, since pigment translocation can be reactivated in permeabilized cells by the addition of exogenous ATP to the lysis buffer. Non-hydrolyzable analogues, including β,γ-imidoadenosine-5′-triphosphate (AMPPNP), β,γ-methylene adenosine-5′-triphosphate (AMPPCP), and ATPγS, will not substitute for ATP in reactivation of movement. Similarly, other nucleotides such as ADP, AMP, GTP, CTP, and ITP, have limited ability to support melanosome aggregation in metabolically poisoned cells subjected to detergent lysis. ATP itself has no effect on intact cells. These results indicate that melanosome aggregation is ATP-dependent and energy-driven, and are consistent with a role for a force-transducing ATPase in particle movement.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 25-27 
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 41-55 
    ISSN: 0886-1544
    Schlagwort(e): Leptodiscinae ; Dinoflagellates ; contractility ; non-actin filaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The Leptodiscinae, a group of marine Dinoflagellates, are good material for the study of contraction though they cannot be collected in abundance. Their cell bodies are flattened anteroposteriorly (Leptodiscus, Leptophyllus, and Leptospathium) and are able to contract suddenly when the surrounding water is disturbed.Electron microscopical observations have shown that the structures responsible for the contraction consist of a layer of parallel filaments located beneath the cell membrane of some specialized parts of the body. These filaments seem to be nonactin (NAF) because of their diameter (2.5-3 nm) and because they are not decorated by heavy meromyosin (HMM). They appear helically coiled and doubly twisted, and form tubular structures when contracted.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 77-87 
    ISSN: 0886-1544
    Schlagwort(e): Chlamydomonas ; flagella ; cell surface ; adhesion ; glycoproteins ; iodination ; lactoperoxidase ; Iodogen ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The Chlamydomonas flagellar surface exhibits interesting adhesive properties that are associated with flagellar surface motility. This dynamic surface property can be exhibited as the binding and movement of small polystyrene microspheres or as the interaction of the flagellar surface with a solid substrate followed by whole cell locomotion, termed “gliding.” In order to identify flagellar surface proteins that mediate substrate interaction during flagellar surface motility, two immobilized iodination systems were employed that mimic the conditions for flagellar surface motility: small polystyrene microspheres derivatized with lactoperoxidase, and large glass beads derivatized with Iodogen. Use of these iodination conditions resulted in preferential iodination of a high-molecular-weight glycoprotein with apparent molecular weight of 300,000-350,000. These results suggest this glycoprotein as a major candidate for the surface-exposed adhesive component that directly interacts with the substrate and couples the substrate to a system of force transduction presumed to be located within the flagellum.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984) 
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    ISSN: 0886-1544
    Schlagwort(e): fibroblast ; permeabilized cell model ; Ca2+-dependent contraction ; calmodulin ; phosphorylation ; myosin light chain ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Human lung fibroblast MRC-5 cells treated with Triton X-100 (MRC-5 cell models) were able to contract in the presence of MgATP and Ca2+ of more than 1 μM. Immunofluorescence microscopy with antibodies to actin and myosin 20,000-dalton (20 Kd) light chain revealed that stress fibers were prominent in MRC-5 cell models. Use of a fluorescent actin probe, 7-nitrobenz-2-oxa-1,3-diazole-phallacidin permitted visualization of contraction of the stress fibers in the presence of MgATP and Ca2+. Of the proteins in MRC-5 cell models, only a myosin 20 Kd light chain was phosphorylated in a Ca2+-dependent manner. This Ca2+-dependent phosphorylation of the 20 Kd light chain closely corresponded with the contraction of MRC-5 cell models: 1) Both phosphorylation of the 20 Kd light chain and contraction of MRC-5 cell models were inhibited by calmodulin antagonists such as N-(6-aminohexyl)5-chloro-1-napthalene sulfonamide. 2) The threshold Ca2+ concentration for phosphorylation of the 20 Kd light chain was similar to that for contraction of MRC-5 cell models. Both were lowered by exogenous calmodulin in a concentration-dependent manner. 3) The 20 Kd light chain was thiophosphorylated by incubation of MRC-5 cell models with an ATP analogue, adenosine 5′-0-(3-thiotriphosphate) only in the presence of Ca2+. After this treatment, MRC-5 cell models lost the Ca2+-dependence for contraction. These results indicate that Ca2+-calmodulin-dependent phosphorylation of myosin 20 Kd light chain is required for contraction of MRC-5 cell models.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 387-401 
    ISSN: 0886-1544
    Schlagwort(e): bull sperm flagella ; motility ; time course ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Detailed measurements were made of the time course of the motion of bull spermatozoa. Fourier analysis of the data showed the time course to be basically sinusoidal within 2% to 3%. An asymmetry in the motion was present, resulting in a second harmonic component in the Fourier spectra of normal sperm of approximately 11% of the main component. When the energy metabolism of the sperm was inhibited or when the external viscosity of the medium was raised, the asymmetry was reduced. When the internal Mg2+ content of the sperm was lowered, the asymmetry was increased. The asymmetries and the corresponding second harmonic components in the Fourier spectra were correlated with the overall bend shape of the sperm and with the curvature of the path in which the sperm were swimming. Model calculations showed that the asymmetry could reside in either the internal active moments in the sperms or in the stiffness of the sperm fiagella.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 443-468 
    ISSN: 0886-1544
    Schlagwort(e): actin ; microfilaments ; HMM ; phagocytosis ; cytochalasin ; Paramecium ; fluorescence microscopy ; electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Using heavy meromyosin (HMM) or the fragment S1 of myosin as probes for actin microfilaments, we studied their organization in Paramecium both by fluorescence and electron microscopy.In interphasic cells, HMM decorates (a) most prominently the periphery of nascent and young food vacuoles and their route during the early phase of their intracellular transit; (b) a thin meshwork radiating from the gullet throughout the cytoplasm; (c) a small area beneath the pore of contractile vacuoles and beneath the cytoproct when open to release food residues. Most of these HMM-decorated structures are in close contact with microtubular arrays. All HMM decoration disappears in dividing cells and in cytochalasin-treated cells. In vivo, the drug immediately blocks food vacuole formation but does not affect cytokinesis, cyclosis, contractile vacuole pulsation, defecation, or nuclear movements.The data show that, as in the cells of other organisms, actin microfilaments form defined arrays that undergo physiologically controlled cycles of assembly/disassembly. These arrays contribute (at least in the phagocytotic process) to diverse types of movement: constriction, membrane fusion, and migration of food vacuoles. However, aside from their massive concentration along the phagocytotic tractus, actin microfilaments are neither major structural components of Paramecium cytoplasm nor the only cytoskeletal components ensuring motility or contractility processes.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 197-213 
    ISSN: 0886-1544
    Schlagwort(e): gelation ; actin ; filamin ; cytoplasm ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: We have compared the meniscus depletion assay and falling ball viscometry, two means of assessing the extent of gelation in actin-based systems using mixtures of actin and the actin-binding protein filamin. We examined the effect of varying the concentrations of actin and filamin in both assays. The interaction of actin and filamin was detected only above a threshold concentration of filamin. This threshold concentration was lower for falling ball viscometry than for the meniscus depletion assay at equal actin concentrations. At constant concentrations of filamin, an increase in actin concentration caused an increase in apparent viscosity measured by the falling ball assay, but a decrease in sedimentability detected by the meniscus depletion assay. The rate of sedimentation of actin was dependent on the molar ratio of actin to filamin. At each molar ratio, the sedimentation of actin was not dependent on the specific concentrations of actin and filamin used. The apparent viscosity was dependent on both the molar ratio and the specific concentrations of actin and filamin. To relate the present results to earlier studies, we examined mixtures of actin and filamin using a macroscopic assay of gelation (tube tipping assay), and polarized light microscopy. The effect of increasing filamin concentration in the four assays was compared at three actin concentrations. Mixtures of actin and filamin whose apparent viscosities were low enough to be estimated by falling ball viscometry were optically isotropic fluids that flowed out of inverted test tubes. Mixtures of actin and filamin in the range of sensitivity of the meniscus depletion assay were either viscous fluids or gels, and were either optically isotropic or anisotropic. Thus, the four assays provide different estimates of gelation. Both the meniscus depletion assay and falling ball viscometry can be used to determine relative gelation activity, but neither can be used as a quantitative assay of gelation.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 183-196 
    ISSN: 0886-1544
    Schlagwort(e): tubulin ; assembly ; mitotic apparatus ; bimane ; fluorescence microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Fluorescent derivatives of cellular proteins that retain their native characteristics have become useful probes to investigate the dynamics of specific cytoskeletal proteins. In the experiments reported here, a previously characterized fluorescent derivative of tubulin, bimane-tubulin [Wadsworth and Sloboda, 1982a], was used to investigate microtubule assembly in vitro. The results demonstrate that bimanetubulin was competent to assemble onto a variety of organizing centers in vitro, including microtubule organizing centers (MTOCs) present in homogenates of sea urchin eggs, isolated mitotic apparatuses (MAs), and lysed mitotic cells. When homogenates of fertilized sea urchin eggs containing MTOCs were incubated with bimane-tubulin at 37°C, discrete areas of linear fluorescence were observed. Only diffuse fluorescence was observed when calcium or colchicine was added to the homogenate or if the temperature was maintained at 0°C. Negative-stain electron microscopy of the fluorescent arrays revealed morphologically normal microtubules radiating from electron dense regions. When mitotic spindles, isolated in glycerol containing buffers and therefore cold stable, were incubated with bimane-tubulin, linear fluorescence was observed emanating from the spindle poles but not from the region occupied by the kinetochores. MAs incubated with bimane-labeled bovine serum albumin or bimane-labeled microtubule-associated proteins showed only diffuse fluorescence. However, when mitotic cells which were hypotonically lysed in the absence of detergents or microtubule stabilizing solvents, were perfused with bimane-tubulin intense fluorescence was observed in the asters and throughout the spindle. Two experiments suggested that the fluorescence observed in the results outlined above was due to the assembly of normal microtubules from the fluorescent subunits. First, the observed fluorescence was sensitive to cold temperataure, which is known to disassemble microtubules. Second, when the isolated, fluorescent MAs were examined by thin section electron microscopy, microtubules of normal diameter were seen. No aggregated material appeared associated with the walls of the microtubules, which might have been expected if the fluorescent protein was nonspecifically adsorbed to the microtubules. The results of these experiments demonstrate that isolated, stabilized MAs support the growth of new microtubules from the spindle poles while labile spindles, present in lysed cells, incorporate fluorescent tubulin throughout the spindle and asters. The significance of these results for hypotheses concerning microtubule assembly and disassembly during mitosis is discussed.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 241-247 
    ISSN: 0886-1544
    Schlagwort(e): cytoskeleton ; centrosome ; tonofilaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: We present observations on the relative location of the centriole and keratin filament cap in motile PtK1 cells. Subconfluent cells were double labeled with anticentriole and antikeratin sera. These preparations revealed that the centriole is separate from, but neighboring, the keratin filament cap. Serial ultrathin sections confirm this observation. These observations are consistent with the idea that the microtubule organizing center and intermediate filament distribution center are not identical or concentric in PtK1 cells.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 403-404 
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 417-430 
    ISSN: 0886-1544
    Schlagwort(e): flagella ; image analysis ; microcomputer ; motility ; parameter estimation ; Simplex method ; spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Parameters to describe flagellar bending patterns can be obtained by a microcomputer procedure that uses a set of parameters to synthesize model bending patterns, compares the model bending patterns with digitized and filtered data from flagellar photographs, and uses the Simplex method to vary the parameters until a solution with minimum root mean square differences between the model and the data is found. Parameters for Chlamydomonas bending patterns have been obtained from comparison of shear angle curves for the model and the data. To avoid the determination of the orientation of the basal end of the flagellum, which is required for calculation of shear angles, parameters for sperm flagella have been obtained by comparison of curves of curvature as a function of length for the model and for the data. A constant curvature model, modified from that originally used for Chlamydomonas flagella, has been used for obtaining parameters from sperm flagella, but the methods can be applied using other models for synthesizing the model bending patterns.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 17
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 169-181 
    ISSN: 0886-1544
    Schlagwort(e): cytoskeleton ; motility ; cell spreading ; epithelial cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Reorganization of intermediate filaments during cell spreading is examined by immunofluorescence, electron microscopy, and time-lapse video microscopy. A juxtanuclear cap, believed to correspond to the intermediate filament distribution center, was observed to be spatially related to the organization of the intermediate filament network as cells spread. A keratin cap was observed, which appeared spontaneously in motile PtK1 cells. Cap formation may be a consequence of retraction of intermediate filaments from the cytoplasm as cells move. The position of this juxtanuclear cap is related to the direction of movement, located on the side of the nucleus near the advancing edge of the cell. As the cell spreads, the cap disappears as the keratin filament network returns to the cytoplasm. Evidence presented here is consistent with the hypothesis that the distribution center mediates keratin filament organization during cell shape change.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 18
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 29-40 
    ISSN: 0886-1544
    Schlagwort(e): microfilaments ; microtubules ; contraction ; collagen gel ; fibroblasts ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In vitro models have been developed recently to study the ability of fibroblasts to generate tensile force within collagen gels. The present study was initiated to assess the role of the cytoskeleton in the cell shape changes and force generation in one such model system. Porcine periodontal ligament fibroblasts (PPLF) were cultured within three-dimensional collagen gels attached to glass coverslips. Fluorescence microscopy, using nitrobenzooxadizole (NBD)-phallacidin labeling for microfilaments and tubulin antibody staining for microtubules, was combined with phase and Nomarski optics to determine the intra- and extracellular architecture of the cells and collagen fibers. Samples were observed from 30 minutes to 24 hours after initiation of cell attachment. During attachment and spreading, NBD-phallacidin staining changed dramatically until large microfilament bundles became prominent. Collagen fiber alignment, compaction, and finally tearing from the coverslip occurred during this time. After release of tension, microfilament bundles were no longer evident. The change in microtubule distribution during these processes was less dramatic, appearing to follow the change in cell shape. These results indicate that microfilaments play an essential role in generating force to align and compact collagen, while microtubules may have a secondary role only.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 19
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 57-71 
    ISSN: 0886-1544
    Schlagwort(e): actin ; calcium ; coelomocytes ; ionophore ; pH ; shape transformation ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: We have investigated the ability of the Ca+ + ionophore A23187 to induce the transformation of petaloid sea urchin coleomocytes to the filopodial form. The response of individual cells to different media was observed with time-lapse phasecontrast video microscopy. In the presence of 1 mM CaCl2, isotonic medium containing 1-5 μM A23187 produces a similar shape transformation to that caused by hypotonic shock. Higher concentrations of ionophore (10-20 μM) induce the formation of filopodia that are thinner and less rigid than those generated by hypotonic shock or low doses of ionophore. A23187 also induces shape transformation in highly flattened cells that do not respond fully to hypotonic shock. The induction of cytoplasmic alkalinization by NH4Cl, methylamine-HCl, or the Na+ ionophore monensin does not induce shape transformation, suggesting that increased intracellular pH is not the stimulus for this process. Ultrastructural changes in cytoskeletal organization were examined in negatively stained detergent-extracted cells. Low doses of ionophore produce filopodia that are indistin-guishable from those of hypotonically shocked cells, with actin filament bundles that are straight and cohesive along their entire length. High concentrations of ionophore produce filopodia with filament bundles that branch repeatedly and splay apart near their tips, forming loops and irregular curves. These results suggest that an increase in intracellular free Ca+ + concentration acts as the trigger that stimulates coelomocyte shape transformation, but that abnormally high concentrations of intracellular Ca+ +, produced by high doses of ionophore, interfere with actin filament bundling.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 20
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 121-128 
    ISSN: 0886-1544
    Schlagwort(e): axonal transport ; ATP ; nucleotides ; saltatory movement ; dynein ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In a permeabilized axon model, exogenous ATP can reactivate intraaxonal saltatory organelle movements (microscopically visible manifestations of fast axonal transport). We have studied the dependence of the reactivated movements on the ATP concentration and have also examined the nucleotide specificity of the reactivation. Organelle transport was visualized in isolated lobster giant motor axons using Nomarski optics and video microscopy. The axons were permeabilized with saponin, and movement was reactivated with ATP or other nucleotides. Some slight movement was seen with ATP concentrations as low as 10 μM. The velocity and frequency of the reactivated transport increased with increasing ATP concentrations up to about 5 mM. Movement was also reactivated by deoxyadenosine triphosphate, but not by AMP-PNP (a nonhydrolyzable ATP analogue), ADP, or AMP. Although other nucleotides (CTP, GTP, UTP, ITP) could reactivate transport, movement equivalent to that produced by 0.1 mM ATP was only seen with tenfold or greater concentrations of the other nucleotides. This pattern of specificity is consistent with the hypothesis that a dynein-like ATPase, rather than a myosin, is involved in fast axonal transport.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 21
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 137-149 
    ISSN: 0886-1544
    Schlagwort(e): anti-fluorescein ; fluorescent analog cytochemistry ; molecular cytochemistry ; microinjection ; actin ; acetamidofluorescein-actin ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Fluorescent analogs of cellular components are finding increasing use in the field of cell biology. The power of this technique can be augmented by the use of antibodies specific for the fluorophore to visualize selectively the fluorescent analog at the electron microscope level. Rabbit antibodies specific for fluorescein were elicited and purified according to published methods (Lopatin and Voss [1971]: Biochemistry 10:208). Immune sera and IgG formed precipitin lines with fluorescein-labeled proteins in Ouchterlony immunodiffusion assays, and significantly quenched the fluorescence of fluorescein-labeled proteins. Immune IgG and Fab fragments decorated fluorescein-labeled actin, but not unlabeled actin, in negative-stained preparations. Anti-fluorescein IgG was used for immunofluorescent localization of fluorescein-labeled actin following microinjection of the fluorescent analog into living cells. This approach was extended to the immunoelectron microscopic localization of the injected analog at the subcellular level by the use of an electron-dense marker coupled to goat anti-rabbit IgG. Many other fluorescent probes also can be used as haptens for production of antibodies. Therefore, a general method for localizing fluorescently labeled molecules at the electron microscopic level is now available. Several other applications of anti-fluorescein antibody in studies involving fluorescent analogs are also suggested.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 22
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 215-226 
    ISSN: 0886-1544
    Schlagwort(e): sperm motility ; flagellum ; axoneme ; microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Iontophoretic application of ATP to the flagellum of the demembranated hamster spermatozoon produced a planar pair of bends at the two ends of the stimulated site. During bend propagation, torsion appeared in the vicinity of the interbend in some responses such that the distal bend was twisted clockwise when viewed from the base of the flagellum. This pattern of propagation is consistent with the instantaneous configurations of free-swimming cells previously described. The technique used here establishes that the three dimensionality arises from propagation per se, and does not depend on forces developed during swimming. The rolling of both free-swimming intact and demembranated spermatozoa was examined by two-color darkground videomicroscopy and the direction of rotation was, as predicted, always anticlockwise. A hypothetical mechanism, involving differential speeds of propagation of active sliding within the active microtubule subset, is proposed to account for the observed waveforms.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 23
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984) 
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 24
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 351-370 
    ISSN: 0886-1544
    Schlagwort(e): axon ; rate ; nervous system ; tissue culture ; cell growth ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A new formula calculates rates of directed axonal growth (elongation or retraction) using measurements of growth cone movements. By explicitly separating changes in axonal length from other nonelongational growth cone movements, the calculated rates reflect the detailed cellular growth mechanisms more directly than previous growth measures. In addition, the formula produces three distinct parameters of axonal elongation: n, a growth step rate; s, a growth step size; and P, a probability that a growth step leads to axonal elongation. For normal and regenerating individual chick and frog axons in culture, the formula has quantitated the following differences: the axon itself can elongate more rapidly in the chick, and the axon elongates in smaller steps in the chick. The underlying dynamics of growth of regenerating axons are quite similar to normal axons, but, in the short term, regenerating axons elongate in larger steps and at a slower rate. The distribution of these new rate measurements suggests that the elongation of axons can be usefully modelled as a one-dimensional stochastic walk.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 25
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 371-385 
    ISSN: 0886-1544
    Schlagwort(e): microtubules ; dynein ; tubulin ; cilia and flagella ; microtubule associated proteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Dynein, obtained from axonemes of Chlamydomonas, binds by both its A and B ends to microtubules assembled from twice cycled (2 ×) and purified (6S) brain tubulin as well as to microtubules in native spindles, thereby inducing microtubule crossbridging. The two ends of the dynein arm exhibit distinct binding characteristics for the different microtubule preparations. Greater than 99% of the dynein arms are bound exclusively by their B ends to microtubules assembled from 6S tubulin in the presence of dynein and decorated to saturation. In contrast, greater than 80% of the dynein arms are bound by both their A and B ends to and, therefore, crossbridge 6S microtubules that are only partially dynein decorated. Binding of the A end of the dynein arm to saturated 6S microtubules can be enhanced by destabilizing the binding of the B end upon addition of ATP and vanadate. These observations suggest that Chlamydomonas dynein arms can bind by their A ends to microtubules assembled from 6S tubulin only when the B ends of the arms either are not bound or are bound but do not occupy all available dynein binding sites. Dynein exhibits a slight preference for binding by its A end to microtubules assembled from 2 × tubulin and containing microtubule associated proteins (MAPs). Approximately 90% of the dynein arms crossbridge adjacent 2 × microtubles that are only partially decorated. But as saturation of these microtubules with dynein is approached, the majority of the arms are bound solely by their A ends, while a smaller percentage are bound by their B ends or by both their A and B ends. These studies indicate that the type of microtubule as well as the degree of saturation of the microtubule with dynein can determine whether microtubule crossbridging occurs.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 26
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 405-416 
    ISSN: 0886-1544
    Schlagwort(e): cardiac muscle ; myofibril ; cell spreading ; Z bands ; alpha-actinin ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Cardiac myocytes were isolated from 5-6-day-old chick embryos and allowed to spread in culture. The distribution of alpha-actinin in the cells was followed for five days in culture by exposing permeabilized cells to rhodamine-labeled alpha-actinin and also by injecting the labeled alpha-actinin into living myocytes. In addition to labeling the Z bands of sarcomeres, the added alpha-actinin also labeled small particles that were usually arranged periodically in linear arrays with a spacing between particles of 0.3-2.0 μm. Actin was localized between the particles of alpha-actinin by means of fluorescein-labeled heavy meromyosin. The punctate localization of alpha-actinin was prominent in pseudopods, behind ruffles, and at the periphery of spreading cells. Long rows of particles of alpha-actinin were often parallel to one another with the alpha-actinin particles in register. These linear arrays appeared to merge laterally to form strands with broader concentrations of alpha-actinin. Other linear arrays were parallel to myofibrils in the cell and some extended outward from the ends of myofibrils. We conclude that during spreading of cardiac myocytes, myofibrils form at the cell periphery behind the extending margins of the cell, and that the aggregates of alpha-actinin found in these areas are nascent Z bands in the forming myofibrils.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 27
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 469-503 
    ISSN: 0886-1544
    Schlagwort(e): cytogel ; actomyosin ; Physarum ; oscillations ; mechanics ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The contractility of actomyosin gels is the basis for a variety of cellular motility phenomena. We present here a mechanical analysis of contractile gels. By making certain hypotheses on the chemical regulation of cytogel contraction we formulate a model for the rhythmic contractions of plasmodia in the slime mold Physarum polycephalum which is in accord with a number of experimental observations.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 28
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984) 
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 29
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 7-23 
    ISSN: 0886-1544
    Schlagwort(e): axoplasm ; elastic modulus ; viscosity ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A magnetic sphere viscoelastometer has been developed to peform rheological experiments in living axoplasm of Loligo pealei. The technique includes the use of a calibrated magnetic sphere viscoelastometer on surgically implanted ferro-magnetic spheres in intact squid giant axons. The axoplasm was discerned to be “living” by the biological criterion of tubulovesicular organelle motility, which was observed before and after experimentation. From these in vivo experiments, new structural characteristics of the axoplasm have been identified. First, analysis of magnetic sphere trajectories has shown the axoplasm to be a complex viscoelastic fluid. Directional experimentation showed that this material is structurally anisotropic, with a greater elastic modulus in the direction parallel to the axon long axis. Second, both magnetic sphere and in vivo capillary experiments suggested that the axoplasm is tenaciously anchored to the axolemma. Third, it was found that axoplasm could be modelled as a linear viscoelastic material in the low shear rate range of 0.0001 to 0.004 s-1. The simplest mechanical model incorporating the discovered properties of the material in this range is Burger's model.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 30
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984) 
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 31
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 89-101 
    ISSN: 0886-1544
    Schlagwort(e): fast axonal transport ; mitochondria ; membrane receptors ; cytoskeleton ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In living tissue, membrane-bound organelles, including mitochondria, move along parallel cytoplasmic pathways. Motion is directed and tends to be confined to a single path. Deviations from this single path motion are rare. When present, however, they tend to occur at points of intersection of cytoskeletal linear elements (LE). Such intersections are relatively uncommon in intact axons and extruded axoplasm. However, we have found that such intersections can be produced in extruded preparations by shear forces directed tangential to the axoplasmic surface.We have studied the detailed behavior of mitochondria in extruded squid axoplasm. Special attention was directed to the relationship between mitochondrial shape changes and orientation of cytoskeletal LE. The most striking of these changes in shape is branching. In this process, the mitochondrion transiently assumes a triradial (three-ended) shape. This appearance may be maintained for seconds to minutes before the normal cylindrical shape is resumed by absorption of either the newly formed end or, more commonly, one of the original ends. The frequency of branching appears to be dependent on the degree of cytoskeletal organization. It becomes more common as the number of apparent intersections between cytoskeletal LE increases. Further, the formation of new ends seems to occur along paths defined by cytoskeletal elements.These observations suggest that the mitochondrial membrane is multivalent. That is, it contains multiple sites capable of interacting with the axonal force generation apparatus. Furthermore, LE in the cytoskeleton may indicate the paths along which these interactions are permissible.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 32
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984) 
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 33
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 155-167 
    ISSN: 0886-1544
    Schlagwort(e): taxol ; microtubules ; mitosis ; mitotic spindle ; calcium ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Taxol stabilizes or promotes the assembly of microtubules. In this report we characterize the rate, extent, and reversibility of taxol stabilization of calciumlabile microtubules in isolated mitotic spindles, principally from embryos of the sand dollar Echinarachnius parma. The intense depolymerizing action of 100 μM Ca2+ was used to assess the extent of stabilization by taxol. Changes in spindle microtubule assembly were evaluated and recorded by measuring changes in spindle birefringent retardation (BR). Membrane-free mitotic spindles, isolated with a calcium-chelating, nonionic detergent buffer, were stored in an EGTA-gylcerol storage buffer to prevent microtubule depolymerization. When perfused with an EGTA-buffer without glycerol, microtubules in these isolated spindles depolymerized gradually over 60-120 min; but in isolated spindles perfused with buffer that contained 100 μM Ca2+, BR decreased by 90% within 2-5 sec. In contrast, spindles that were pretreated for 3 min with 1 μM taxol, or for about 30 sec with 10 μM taxol, lost less than 10% of their initial BR when perfused with buffer containing 100 μM Ca2+. The rate and extent of microtubule stabilization by taxol depended on both the concentration and the duration of exposure to taxol. Taxol stabilization was reversible. After a 15 min preincubation with 1 μM or 10 μM taxol then washout, stability of spindle BR to 100 μM Ca2+ decreased exponentially with a time constant of 30-60 min. Thus taxol dissociates from spindle microtubules at significant rates; taxol-stabilized microtubules are not “fixed.”
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 34
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 304-305 
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 35
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 305-314 
    ISSN: 0886-1544
    Schlagwort(e): cell surface motility ; axopodia ; reticulopodia ; Allogromia ; Echinosphaerium (Actinosphaerium) nucleofilum ; surf-riding ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The mechanism responsible for the energy-dependent movement of membrane components (ie, surface motility) is unknown. Recently a potentially unifying model, termed “surf-riding” [Hewitt, 1979] or “surf-boarding” [Berlin and Oliver, 1982], has been proposed to explain surface motility. Using phase-contrast light microscopy and membrane surface markers (polystyrene microspheres), we have tested the surf-riding/surf-boarding hypothesis on two protozoan systems: the axopodia of the heliozoan Echinosphaerium nucleofilum and the reticulopodial networks of the allogromiid foraminiferans Allogromia laticollaris and Allogromia sp, strain NF. Our evidence indicates that surface motility, as displayed by these organisms, does not occur by a surf-riding/surf-boarding mechanism. Previouś observations on surface motility associated with the Chlamydomonas flagellum indicate that this system is also incompatible with the surf-boarding/surf-riding hypothesis.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 36
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 269-281 
    ISSN: 0886-1544
    Schlagwort(e): microtubules ; microfilaments ; filopodia ; cell spreading ; coelomocytes ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Sea urchin coelomocytes were used as a model system to investigate the distribution and role of microtubules and microfilaments in cell spreading and filopodial formation. By using immunoblot characterized antisera to tubulin and actin coupled with immunofluorescence techniques, cellular protrusions were seen to contain actin filaments but no microtubules. Cells depleted of MT's by cold and colcemid treatments could attach, spread, and transform to the filopodial morphology normally.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 37
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 231-239 
    ISSN: 0886-1544
    Schlagwort(e): pseudostereoscopy ; particle speed distribution ; velocity distribution ; fast axonal transport ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: We describe a simple method for direct visualization of the velocity distribution of particles moving against an immobile background. The technique involves pseudostereoscopic viewing of image pairs separated by an appropriate time interval in a sequential recording of the subject. Under these conditions, the positive or negative parallax arising from particle motion results in the binocular image of a particle being perceived as raised or lowered relative to an immobile background plane depending on its direction of movement, and with the degree of perceived elevation being proportional to its speed. In effect, the binocular optic axis becomes a velocity (speed) axis under these conditions. The technique is illustrated with examples of image pair sequences showing fast axonal transport in lobster and squid axons using video-enhanced differential interference contrast microscopy. However, the pseudostereoscopic method is quite generally applicable to both microscopic and macroscopic time-dependent phenomena. Particle speeds can be quantitated using standard procedures for measuring frame-to-frame particle displacements, or alternatively, by determination of parallax using stereogrammatic methods. It should be also readily adaptable for on-line monitoring of particle velocity distribution, particularly in video systems where frame buffers can be utilized to extract and present serial image pairs having any desired time separation from video-taped sequences.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 38
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 283-295 
    ISSN: 0886-1544
    Schlagwort(e): axonemal mutants ; Ca++ response ; ciliary reversal ; electrophysiology ; models ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Six mutants of Paramecium tetraurelia, which display altered axonemal responses to Ca++, are described. The mutants, designated atalantas, are impaired in their ability to swim backward when stimulated by ions or heat; instead they spin very rapidly in one place. Three mutants, ataA1-3, are completely unable to swim backward. The three lines, however, can be distinguished from one another by their forward swimming velocities. The remaining three mutants are leaky. ataB swims backward briefly when stimulated, then stops and spins in place. ataC and ataD are extremely leaky and only display the spinning phenotype at elevated temperatures. An electrophysiological analysis reveals that all six mutants have normal membrane properties, including the Ca++ inward current under voltage clamp. When the membrane is disrupted so as to allow the axoneme free access to Ca++, wild-type cells swim backward, but the mutants do not. These data indicate the site(s) of lesion in the mutants is in the axoneme or in some step linking Ca++ influx and the axoneme, not within the ciliary membrane. These mutants may be useful in investigating the role of Ca++ in the regulation of axonemal motion.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 39
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 297-303 
    ISSN: 0886-1544
    Schlagwort(e): exocytosis ; chromaffin cells ; vesicle release ; light microscope ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Cultured bovine adrenal medullary chromaffin cells were stimulated with the secretogogues Ba2+ or carbamyl choline plus Ca2+. With video-enhanced contrast, differential interference contrast microscopy, small vesicles were found to appear on the cell surface during stimulation. The structures were of lower refractive index than the cytoplasm, and their appearance required several tenths of a second. The vesicles are thought to correspond to omega figures seen with electron microscopy due to exocytosis. Many of the structures disappeared within a few seconds, but some appeared to coalesce into larger structures. The large structures may lead to the vacuoles that have been demonstrated to be present following stimulation. The nature of the cellular elements responsible for the vesicle which appeared on the surface was not found with either differential interference or interference reflection microscopy. The simplest explanation is that the refractive index of the elements is similar to that of the cell, and therefore the elements cannot be seen.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 40
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984) 
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 41
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 103-119 
    ISSN: 0886-1544
    Schlagwort(e): cilia ; metachrony ; serum immunoglobulins ; IgM ; Mytilus edulis ; cystic fibrosis ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Human IgM and a bovine, IgM-enriched serum fraction isolated from normal adult serum at concentrations of 0.25-1 mg/ml protein induced a pronounced increase in the metachronal wavelength of the lateral (L) cilia of the sea mussel Mytilus edulis without altering their beat frequency. This change in activity was indistinguishable from that induced by 50% adult human or bovine serum. At protein concentrations ranging from 1-9 mg/ml, human IgG or a bovine, IgG-enriched serum fraction had no or little effect on the activity of the L cilia. Similarly, neither monomeric (8S) human IgM (0.25 mg/ml) nor monospecific pentameric IgM (1 mg/ml) isolated from Waldenström's macroglobulinemia patients altered the metachrony of the L cilia. Indirect immunofluorescence demonstrated that both bovine and human IgM became attached almost exclusively to the L cilia, while very little bovine or human IgG was found to associate with these cilia.The results of this study suggest that serum IgM specifically binds to the L cilia of Mytilus in an antigen-antibody manner and agglutinates adjacent cilia into blocks or bundles, thereby increasing the coupling between cilia. As a result, the wavelength of the metachronal coordination is increased. The origin of these ciliary antibodies and their significance to ciliary bioassays used to monitor serum for the detection of cystic fibrosis are discussed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 42
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 151-153 
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 43
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 227-229 
    ISSN: 0886-1544
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 44
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 4 (1984), S. 249-267 
    ISSN: 0886-1544
    Schlagwort(e): Paramecium ; trifluoperazine ; cilia ; calmodulin ; calcium ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Trifluoperazine (TFP), a drug that binds to Ca2+-calmodulin (CaM) complexes, altered swimming behavior not only in living paramecia, but also in reactivated, Triton-extracted “models” of the ciliate. By comparing the responses of living cells and models, we have ascertained that two sites of drug action exist in paramecium cilia. Swimming movements were recorded in darkfield stroboscopic flash photomicrographs; this permitted accurate quantitation of velocities and body-shape parameters. When living paramecia were incubated in a standard buffer containing 10 μM TFP, their speed of forward swimming fell over several minutes and their bodies shortened. Untreated paramecia backed up repeatedly and frequently upon transfer to a solution containing barium ions (the “barium dance”), but cells preincubated in TFP did not “dance.” Instead they swam forward slowly for long periods of time without reversing and occasionally then exhibited abnormally prolonged reversals. W7 effects on swimming mimicked low doses of TFP, and the analog W5 did not visibly alter normal swimming patterns. These results suggest that TFP induces a decrease in the intracellular pCa of living paramecia, perhaps by reducing the efficiency of a calmodulin-activated calcium pump in the cell membrane. Paramecia extracted with Triton X-100 and reactivated to swim forward (7 ≥ pCa ≥ 6) were not affected by addition of up to 40 μM TFP to the reactivation medium. We conclude that the main drug effect in living cells is probably not at the axoneme. However, at low pCa, TFP directly affected the ciliary axoneme to shift its behavior to one characteristic of a higher pCa: TFP inhibited backward swimming in models reactivated at pCa 〈 6; instead they swam forward or rocked in place. The mechanism of ciliary reversal in paramecium may therefore depend on an axonemal Ca+-sensor, possibly bound CaM, which is affected by TFP only at low pCa, as has been postulated for other types of cilia.
    Zusätzliches Material: 11 Ill.
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  • 45
    ISSN: 0886-1544
    Schlagwort(e): microtubule ; tubulin ; MAPs ; calcium ; mitosis ; unfertilized sea urchin egg ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Cytoplasmic tubulin purified from unfertilized sea urchin eggs self-assembles in the absence of microtubule-associated proteins (MAPs) [Suprenant and Rebhun, 1983; Detrich and Wilson, 1983] with a critical concentration for polymerization of 0.8 mg/ml at 15-18°C, a value well below the 3 mg/ml tubulin present in these eggs [Pfeffer et al, 1976]. Studies of the calcium sensitivity of unfertilized S. purpuratus (sea urchin) egg tubulin were initiated to help understand how this tubulin is maintained unassembled in the unfertilized egg. Egg microtubules, assembled at physiological temperatures (15-18°C) were depolymerized by a 100-fold lower free calcium concentration than egg microtubules assembled at the higher temperatures (25-37°C) generally used to assemble mammalian brain microtubules. The initial rate of egg microtubule assembly was much more sensitive to calcium than was microtubule depolymerization at steady state at 37°C. However, both processes were sensitive to near physiological free calcium of free calcium for depolymerization than microtubules assembled at 18°C from egg tubulin alone. While calcium regulatory MAPs have not yet been found in sea urchin eggs, the fact that brain MAPs interact with egg tubulin and regulate both its critical concentration for polymerization [Suprenant and Rebhun, 1983] and its calcium sensitivty, suggests that such regulatory molecules exist. These results suggest that sea urchin egg tubulin assembly in vivo could be controlled by variations in interacellular calcium levels acting in concert with urchin egg proteins similar in function to brain MAPs.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 46
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1927) 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 47
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1927), S. 299-345 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The chondriosomes are first recognizable as two clusters in contact with the nuclear wall. Beneath each cluster lies a chromosome. This relationship is constant and indicates that these two chromosomes play a part in the growth and development of the chondriosomes. The two masses fuse and the single mass grows considerably during the early growth period. Later it breaks up into a number of threads which become rings in the late growth period. The rings fuse into the large nebenkern which plays the usual rôle in the formation of the tail.The Golgi material is first seen outside of the chondriosomal cap. Early in the growth period, it breaks up into Golgi bodies which remain distributed in the cytoplasm during the growth period and spermatocyte divisions. About the midgrowth period a large number of spheres suddenly arise. Since they later fuse to form the idiosome, they are called the proidiosomal spheres. These spheres, which may originate in the Golgi bodies, remain scattered in the cytoplasm during the growth period and spermatocyte divisions. In the spermatid the Golgi bodies collect about the idiosome to form the acroblast. The Golgi remnants pass into the cytoplasm of the tail, while the acrosome elongates into a tail-like structure at the anterior end.The centriole was followed with unbroken continuity from the midgrowth period into the middle-piece of the sperm.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 48
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1927), S. 521-546 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The literature on the general subject of freezing and survival both in plants and in animals is briefly reviewed and a bibliography given. Insects representing three ecological groups, (1) the oak borers - exposed to temperature extremes normally; (2) stored-products insects representing supposedly a tropical or subtropical group, and, (3) aquatic insects never exposed to temperatures lower than 0°C., were chosen for this study. Determinations of the freezing and undercooling points were made during the yearly cycle.Both the stored-products insects and the aquatic insects studied showed no periodicity in freezing or undercooling. The oak borers showed marked periodicity. The freezing-point varies directly with the moisture content. Cold-hardiness was produced experimentally by, (1) exposure of insects to low temperatures and, (2) by dehydration. Loss of cold-hardiness was produced experimentally by combinations of high temperature, food, and high relative humidity. The freezing-point ordinarily found corresponds with that of the blood. Repeated freezings of the same insect or tissue showed no hysteresis. There exists in certain insects a secondary freezing-point below that ordinarily found. Oak borers in summer condition die at the first freezing-point; in fully hardened condition they die at the secondary freezingpoint.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 49
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 1-20 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The ant Formica exsectoides F. builds mounds with some reference to sunlight, and measurements of internal temperatures have shown them higher in upper parts of the mound, but different in different faces of the mound - all higher than the earth outside the mound.Inside temperatures are not constant; they are due to the sunshine. The mound is so fabricated that the internal temperatures are conserved during the night. The ants make use of the differential internal temperatures for rearing broods.Some mounds show bilateral symmetry dependent upon sun exposure.Measurements of rate of running of these ants show a falling off with lower temperatures, and possibly this is one factor in the smaller development of northerly aspects of these mounds.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 50
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 313-339 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The rates of oxygen consumption of single pupae of blowflies (Phormia terraenovae, Phormia regina, Lucilia sericata), of the flesh fly (Sarcophaga sarracenioides Aldrich), of the Mediterranean flour moth (Ephestia kuehniella), and of the bee moth (Galleria mellonella) during metamorphosis, until emergence, have been determined. The record for each pupa, with the exception of those of blowflies, is practically continuous day and night during the period of pupal development which lasted from 140 to 300 hours, according to the species, at the temperatures used. During pupal development there is first a period of decrease in rate, which is later followed by a steady increase until a short time before emergence, when a sudden decrease occurs.The ‘oxygen curves’ of the blowfly pupae (Diptera) are quite different from those of the flour-moth and bee-moth pupae (Lepidoptera), although all are of the same general U-shaped type. There are strong indications of a specific difference in the curves of the blow-fly pupae. The flour-moth pupae curves differ slightly from those of the bee-moth pupae. During the major part of development the rates of O2 consumption of pupae of both sexes of bee moth and flour moth are about the same, but near the end of metamorphosis the females have higher rates than the males. No such sex difference appears among the dipterous pupae used.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 51
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The results of the study of certain factors which affect encystment in Didinium nasutum indicate the following: Absence of food constitutes an adverse environmental condition which induces encystment in approximately 50 per cent of the didinia subjected to it, though the presence of a certain amount of food in the cell body is requisite for encystment. The prevention of encystment for 750 generations does not affect the percentage of didinia which encyst in the absence of food, and hence Didinium does not become progressively more disposed to encystment as generations pass. Conjugation does not affect the percentage of didinia which encyst in the absence of food. Metabolic by-products of Paramecium inhibit encystment to a striking degree when didinia are deprived of food in the presence of these products. Metabolic waste of Didinium markedly facilitates its encystment in the absence of food. Hay-infusion culture fluids of different ages have singularly diverse effects on the encystment of didinia in the absence of food; recently prepared infusions inhibit encystment; infusions four to six days old induce encystment in 90 to 100 per cent of the specimens, and infusions seven to fourteen days old, in approximately half of the specimens.
    Zusätzliches Material: 8 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 52
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 89-115 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The investigation is based upon hemal nodes of dog, man, and sheep. The material can be arranged in a regressive series leading from a typical lymph node, except for the occurrence of blood in parenchyma and sinuses, to a lymphoid structure at a late stage of involution. These structures uniformly lack lymphatics. There is no evidence of direct luminal connection between the blood-vascular supply and the sinuses. The observation that certain cervical and subcutaneous lymph nodes of the rabbit undergo a myeloid metaplasia following atrophy and disjunction of their lymphatics is used as an explanatory key of hemal nodes. According to our view, hemal nodes represent stages in the involution of transient lymph nodes. Disjunction of the lymphatics leaves the sinuses filled with entrapped lymphocytes. These differentiate into erythrocytes. These red blood cells may disintegrate and pass into solution or be removed either by giant cells or mononuclear phagocytes. Late stages in this process are represented by small irregular masses of lymphocytes, with wide sinuses practically free of blood.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 53
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927) 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 54
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 29-87 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The anlage of the abducens musculature appears first at 24-25 somites as a condensation situated dorsal to the mandibular arch.The anlage of the superior oblique grows forward from a mesodermal condensation situated in the maxillomandibular region, termed for convenience the maxillomandibular condensation. This last consists of three parts: (1) the anlage of the superior oblique: (2) the anlage of the abducens musculature, and, (3) an intermediate region.The intermediate portion of the maxillomandibular mass forms a condensation with which the anlage of the abducens musculature fuses. Its fate is, therefore, similar to that of the so-called ‘muscle E’ of elasmobranchs, which has been described as fusing with the lateral rectus. How much muscle is formed from the intermediate condensation in the chick has not been determined.The development of the pyramidalis and quadratus nictitans muscles, derivatives of the abducens complex, is described.The premandibular head cavities are replaced by solid mesodermal condensations, on the surface of which the anlagen of the oculomotor muscles appear. The premandibular mass expands laterally and anteriorly over the bulbus, carrying the oculomotor muscles to their respective positions on the bulbus.Portions of the premandibular and maxillomandibular condensations not involved in eye-muscle formation take part in the formation of choroid and sclera.The growth shiftings of the eye muscles are analyzed. The order of their appearance is commented upon.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 55
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 127-216 
    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 represents the first critical investigation on the development of the embryonic skull of the porcupine. A complete series of stages makes it possible to trace the developing chondrocranium from its first formation in precartilage to its later transformation into cartilage bone. Concurrent with this growth is the investment of the cartilaginous cranium by membrane bone.The very primitive nature of the chondrocranium offers an excellent opportunity to discuss the existing problems of the embryonic skull from a new angle. Evidence is presented in support of the assumption that the ala temporalis is the homologue of the cynodont epipterygoid. The lamina parietalis develops from a single chondrifying center, thus producing a different arrangement of parietal elements from that found in most mammals. New evidence as to the relationship of the dens epistrophei and basal plate is presented. The position of the internal carotid artery on entering the cranium is different from the condition found in most mammals and throws new light on the interpretation of surrounding structures. The presence of a structure comparable with the crista longitudinalis of Lacerta shows close affinity to the solum nasi of more primitive forms.The great specialization of the face is seen in the early and rapid growth of the membrane bones. The chondrocranium is long persistent and cartilage bone appears late in embryonic life.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 56
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927) 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 57
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 417-465 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Observations indicate that this Balantidium from the guinea-pig is Balantidium coli, the form found in the pig and man. The lengths and breadths of this Balantidium and the ratios of length to breadth are very close to the measurements and ratios given by McDonald for B. coli. When plotted, the body lengths of the guinea-pig parasites appear in two groups, the smaller individuals being the exconjugants. Many of these exconjugants resemble Neiva's B. caviae. The structure of the Balantidium from the guinea-pig is essentially identical with that of B. coli as given by McDonald.Fission and conjugation of this ciliate follow the general course found in a number of other ciliates. During fission the micronucleus divides and the daughter micronuclei migrate to each end of the macronucleus before the latter divides. In conjugation there are two divisions of the micronucleus, one of these nuclei dividing to form the pronuclei. Pronuclear exchange and fusion are followed by a heteropolar division of the synkaryon, resulting in the formation of the new macronuclear and micronuclear anlagen.The parasite was found in the intestinal tissue of the host. No reproductive stages were found in the cysts. New hosts are invaded through contamination of the food and drink with the cysts.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 58
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: By the use of a satisfactory technique, excellently preserved spermatogenetic tissue was had both for Rattus rattus and Rattus norvegicus. The careful examination of twelve spermatogonial cells of the former species and of twenty in the latter species shows that R. rattus has forty diploid chromosomes and R. norvegicus, forty-two. A careful examination of the haploid cells of both species, both in the first and in the second spermatocyte divisions, confirms the diploid determinations.Both species have an unequal pair in the spermatogonial divisions and the finding of a similar unequal pair in the first spermatocyte division constitutes the evidence for an X-Y mechanism in each. A comparison of the morphology of the first spermatocyte tetrads in the two species reveals the presence of a large K-shaped chromosome in R. norvegicus which is not present in R. rattus. Furthermore, a comparison of the X-Y complex in both the spermatogonial and first spermatocyte divisions shows that these are morphologically different in the two species, the Y in particular being markedly dissimilar in size. A short discussion as to the bearing of these findings on the questions of the origins of the two species and their known intersterility is presented. The marked similarity of the tetrads of the black rat to those described for the mouse is noted.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 59
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 3-17 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The choanoderm and pinacoderm of representatives of the two families of Homoscleromorpha sponges, the Oscarellidae and Plakinidae, have been examined by transmission and scanning electron microscopy. Different fixative procedures have shown the dramatic influence of fixation conditions on the morphology of choanocytes. These two families of sponges have the following morphological features in common: flagellated endopinacocytes with short apical microvilli and basal pseudopods; the presence of a very thin and dense sheet of matrix material which limits the mesohyl. There are, however, only minor differences in the flagellar morphology, granule content, and anchoring system of their choanocytes.Two findings are of particular interest: (1) the presence of glycocalyx bridges between the microvilli of the choanocyte collar; and (2) the discovery of a new cell type, the apopylar cell, which has a morphology intermediate between that of pinacocytes and choanocytes. The apopylar cells limit the apopylar opening of the choanocyte chamber and indicate the transition between choanoderm and pinacoderm.
    Zusätzliches Material: 22 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 60
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 19-28 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Each antenna of both sexes of adult Rhodnius prolixus has approximately 570 mechanosensitive neurons that innervate five morphologic types of cuticular mechanosensilla: campaniform sensilla, tapered hairs, trichobothria, and type I and type II bristle sensilla. Each campaniform sensillum and tapered hair is presumably innervated by one mechanosensitive bipolar neuron and probably functions in proprioception. The campaniform sensilla being located at the base of the scape could monitor the position of the antenna. Tapered hairs are found at the distal margin of flagellar segment I and projecting laterally from the bases of the pedicel and scape. They probably provide information about the relative positions of the antennal segments. Seven trichobothrium are located on the pedicel and three on flagellar segment I. Each trichobothrium has a long filamentous hair inserted into the base of a socket that extends inwardly as a cuticular tube and is innervated by one bipolar neuron with a tublar body, a parallel arrangement of microtubules associated with electron-dense material. The trichobothria may respond to small variations in air currents.Type I bristles occur at the base of the antenna and are the most numerous type of mechanosensillum; an average of 452 occur on each antenna of females and 440 on males. The bristle is curved toward the antennal shaft and is serrated distally. Type II bristles are located distally and are the second most numerous type of mechanosensillum; an average of 88 were counted on each antenna of females and 94 on males. The type II bristle is straight with small, longitudinal, external grooves and projects laterally from the antennal shaft. Each type I and II bristle sensillum is innervated by a bipolar neuron whose dendrite is divided into an inner and outer segment. The outer segment is encased by a dendritic sheath which may be highly convoluted and distally contains a tubular body. Two sheath cells are associated with each sensillum. Both types of bristle sensilla have a tactile function.The tubular bodies of both types of bristle sensilla have a complex structure indicating that they are very sensitive. Variations in the amount and arrangement of the electron-dense material at the tip of the tubular bodies may reflect differences in viscoelastic properties that underlie functional characteristics.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 61
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 69-79 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Fine structural study indicates that the neuromuscular system of stage I polyps of Aurelia aurita is exclusively ectodermal.The three major muscle fields are the radial muscles of the oral disc, the longitudinal muscles of the tentacles, and the muscle cords of the septae and the column; the muscle fields are in physical continuity at the peristomial pits and share a common innervation and type of myofibril. The myofibril is striated in the tentacle base, in the outer oral disc, and in the upper part of the muscle cord; it grades into a smooth muscle toward the tentacle tip, the mouth, and the lower part of the cord. There is a fourth field of longitudinal smooth muscle in the pharynx.The nervous system consists of an epithelial sensory cell in the tentacle and a single type of neuron found in the subepithelial layer of the tentacle, oral disc, and muscle cord. The lack of gap junctions suggests that there is no nonnervous conduction system. The subepithelial layer also contains three types of fibers and a type of soma which cannot be characterized as neuronal. The soma is identified as the “neurosecretory cell” described in Chrysaora. The absence of neuromuscular elements in the column and stolon distinguishes the Aurelia aurita collected from Washington, USA, from English polyps previously described.
    Zusätzliches Material: 28 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 62
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 125-144 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The structure and interrelationships of the mouthparts and of the food canal and its accessory cephalic structures of the females of Simulium venustum are described through microscopic observations. The mouthparts that enter the would during feeding are the mandibles, maxillary laciniae, hypopharynx, and labrum and collectively form a “syntrophium.” The labium and labellar lobes, which do not enter the wound, ensheathe the syntrophium distally and must be retracted to allow biting.We present an interpretation of mouthpart function during biting that emphasizes how biting steps are accomplished and what sensory structures are used to monitor the process. Four phases of biting are identified: (1) initial penetration of the skin effected by the mandibles; (2) consolidation of mouthpart position involving anchoring the syntrophium into the wound by means of the barbed laciniae; (3) diet sampling and active feeding - food (blood) is pumped by three groups of muscles forming two functional pumps, one located in the cibarium, the other in the pharynx. These pumps are separated from each other and from surrounding regions of the food canal by valve muscles making the pumping process a complex and highly coordinated series of muscular contractions; and (4) mouthpart disengagement involving removal of the laciniae, thus releasing the syntrophium from the wound.
    Zusätzliches Material: 30 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 63
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 145-157 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Light and electron microscopic techniques were used to study the cellular and ultrastructural components of the regenerating adult eye of the marine prosobranch gastropod Ilyanassa obsoleta. Behavioral tests were used to determine return of vision in animals with generated eyes. As early as 3 days after removal of the adult eye, the regenerating eye primordium appeared as a pigmented mass of cells that invaginated from the surface epithelium in the area of the wound. Twelve days after eye removal, the regenerating eye was very similar to the postmetamorphic juvenile eye and to the adult eye: It contained a retinal layer, as well as an extracellular lens, cornea, connective tissue capsule, and forming optic nerve; vision had returned. Growth of the eye and its components was linear; size ratios established among forming eye components were maintained during growth.The events of eye regeneration appear to recapitulate embryonic eye formation. The sequence of invagination, pigmentation, and lens, optic nerve, and retinal pattern formation are similar.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 64
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 179 (1984), S. 305-321 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The freeze-fracture technique has been used to obtain detailed information about cuticular constituents and outgrowths of the external skeleton of labella and antennae in the bluebottle fly Calliphora vicina and the antennae of the small moth (Yponomeuta spp.). The lamellated exoskeleton has a fibrous endocuticle and an exocuticle lacking fibers. Ductuli connecting the inside of the animal with the outside run perpendicularly through the endocutile and at angles of up to 45° in the exocuticle. Skeletal outgrowths lack fibers and display fracture features similar to those of the exocuticle. Among those having neuronal endings, gustatory, olfactory, and tactile hairs can be recognized. Noninnervated outgrowths can be subdivided into scales and pseudotrichia. Criteria such as shape, length/width-ratio of hairs, texture, presence and place of pores, shape of pores, and form of the socket or base are presented for further classification. Cuticular features of single-walled olfactory hairs of Calliphora are compared with those of several other species. Based on the shape of the pores, five types of hairs can be distinguished using literature data. It is concluded that the freeze-fracture technique is a valuable tool with which to describe the microarchitecture of the insect exoskeleton and supplements scanning electron microscopy, which is useful for describing the overall skeletal features.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 65
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 37-54 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The external morphology of contact-chemoreceptive hairs (taste hairs) of six fly species, Calliphora vicina, Lucilia caesar, Musca domestica, Phormia terranovae, Sarcophaga carnaria and Stomoxys calcitrans, is described. The species can be distinguished by the differences between the patterns of taste hairs at the ventral side of their prothoracic tarsi. Taste hairs can be subdivided into morphological types, using the shape of the cuticle around the apical pore as criterion, even though this shape changes slightly on opening and closing of the pore. Light microscopical studies reveal that the nature and osmolarity of stimuli are decisive for the effect stimuli have on the shape of the top of the labellar hairs. The motions of the apical cuticle appear to be reversible.Gentle ultrasonic treatment preserves the shape of the cuticle of the top and the diameter of the pores on fluid stimulation. This technique makes it possible to study the effect of a previous stimulation on both tarsal and labellar hairs with the scanning electron microscope. It is supposed that stimuli can affect cuticular components around the pore, producing volume changes in that cuticle which alter the diameter of the pore.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 66
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984) 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 67
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 81-103 
    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 of the ganglia and nerves of the stomatogastric nervous system and the innervation of the extrinsic and intrinsic muscles are described. Median unpaired frontal and hypocerebral ganglia and paired ingluvial ganglia are present. The anterior pharynx is innervated by branches of the frontal nerve and by the anterior and posterior pharyngeal nerves, originating from the frontal ganglion. The posterior pharyngeal nerves are linked to nerves innervating the posterior part of the pharynx which have their origin in the hypocerebral ganglion, the anterior portion of which has previously been regarded as part of the recurrent nerve. Paired esophageal nerves run the length of the esophagus and crop between the hypocerebral and and ingluvial ganglia, innervating the muscularis by serial side branches. From each ingluvial ganglion runs an ingluvial nerve which innervates the gizzard and a cecal nerve which innervates the midgut and its ceca. At the posterior end of the midgut there is a poorly developed nerve ring. Nerves running posteriorly from this nerve ring link the stomatogastric nervous system with the proctodeal innervation from the terminal abdominal ganglion.Multipolar peripheral neurons are present on the muscularis of the whole of the foregut, rather randomly distributed on the crop and gizzard but forming fairly definite groupings at some points on the pharynx. Though of varied appearance, these cells could not be divided into discrete morphological categories. Peripheral neurons on the midgut are of different and characteristic morphology, though a few cells of the same appearance as those of the foregut occur at the midgut-hindgut boundary. Nerve fibers on the gut almost invariably terminate on the fibers of the muscularis.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 68
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 171-171 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: No Abstracts.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 69
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 213-221 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The bursa compulatrix of the Monarch butterfly was investigated utilizing light microscopy, histochemistry, and scanning and transmission electron microscopy in order to relate its morphology to the release of sperm from the spermatophore. The bursa has a row of large chitinous teeth on either side of the organ. The dorsal and ventral surfaces are covered with chitinous plates, the plates having bristles on one side. A single layer of cells lies under both the plates and teeth, one columnar cell under each plate, one cuboidal cell under each tooth. The toothed area has no muscle cells. However, the dorsal and ventral hemispheres of the bursa each have a crescent-shaped packet of muscle fibers that traverse the organ; there are no longitudinal fibers. Spermatophores with thick walls were found in the bursal lumen. Morphological evidence suggests that the presence of the spermatophores is sensed by the bristles and that the packets are opened by contraction of the muscles bringing the large teeth into contact with the spermatophore wall.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 70
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 181 (1984), S. 21-28 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Shells from eggs of the turtle Kinosternon flavescens were examined during different stages of development with light and scanning electron microscopy. Prior to initiation of the calcareous layer, organic spheres or cores appear on the outer surface of the shell membrane. Presumably, these cores nucleate deposition of the mineral layer of the eggshell. Growing shell units of the mineral layer are rounded and nodular in shape, crystallites of adjacent shell units do not interlock, and numerous spaces occur between shell units. As growth continues, most of the spaces between shell units are obliterated, and shell units become more elongate in form. The calcareous layer of partially shelled eggs resembles the calcareous layer of flexible-shelled eggs of emydids and chelydrids. Eggshells assume the morphology typical of rigidshelled chelonian eggs only at an advanced stage of shell formation. These observations indicate that rigid and flexible eggshells may form by fundamentally similar mechanisms, with length of shell growth being the primary determinant of whether shells are flexible or rigid.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 71
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 181 (1984), S. 69-86 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Hymenopteran venom glands are epidermal glands that have evolved from female accessory reproductive glands. In the honey bee, Apis mellifera L., the venom gland shows many of the fine structural features of primitive glands. A honey bee venom gland is a simple, long, thin, distally bifurcated structure, opening into an ovoid reservoir. Along most of the length of the gland are similar secretory units that have four major components (secretory cells, duct cells, ducts, and end apparatuses), except in the part of the gland proximal to the venom reservoir, where the secretory units resemble those around the venom reservoir. In the latter secretory units a funnel structure occurs between the duct (which is shorter than that of the secretory units of the gland) and the end apparatus. This funnel may be important in protecting the secretory cells around the reservoir from the cytolytic activity of the complex chemical mixture constituting the venom.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 72
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 181 (1984), S. 1-8 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The internal reproductive apparatus of female Platynotus punctatipennis is composed of the paired ovaries, paired lateral oviducts, common oviduct, spermatheca associated with its accessory gland, and a bursa copulatrix. The accessory (colleterial) glands are absent. The ovary is made up of a large number of telotrophic ovarioles which are covered by a double-layered peritoneal sheath. The terminal filament is separated from the germarium by the basement membrane of the latter and consists of a syncytial core surrounded by the peritoneal sheath. Nutritive cords are absent. The pedicel shows highly eosinophilic and PAS-positive secretion of obscure origin. The spermatheca reveals a number of interesting features. It is composed of a pair of sperm-storing tubules, enclosed in a very thin muscle layer. A winecup-like structure, provided with a thick coat of circular muscles, connects the spermathecal gland with thespermathecal duct. Four types of intimal linings occur in the spermatheca and its associated structures. The wine-cup-like connection and four types of intima are entirely new features observed. Histology of the various parts of the reproductive apparatus is described.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 73
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 181 (1984), S. 319-331 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The telencephalic medial wall of the lizard Psammodromus algirus was studied using Golgi and conventional light microscopic techniques. The area is formed by two different cytological fields - medial cortex and dorsomedial cortex. These two cortices possess three layers dorsoventrally: a superficial plexiform layer, a cellular layer, and a deep plexiform layer. The alveus, a deep fiber system, runs adjacent to the ependyma. Four classes of neurons are found in the cellular layer of the medial cortex on the basis of soma shape, dendritic pattern, and position in the layer: horizontal, double pyramidal, and candelabra cells. Solitary cells are present in the superficial and deep plexiform layers of the medial cortex. Those of the superficial plexiform layer are stellate cells. Horizontal and vertical cells are found in the deep plexiform layer. Double pyramidal cells are the most frequently impregnated in the cellular layer of the dorsomedial cortex. In addition, candelabra cells are present at the lateral end of the layer. Two cell types are found in the deep plexiform layer of the dorsomedial cortex: solitary pyramidal cells and, among the fibers of the alveus, horizontal cells. Ependymal tanycytes line the ventricular surface, and protoplasmic astrocytes are found in the plexiform layers of both medial and dorsomedial cortices.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 74
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 117-125 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In the early cleavage stages of Ascaris the homologous chromosomes are of unequal length. Measurements show that these homologues fall into two sharply defined groups suggesting their biparental origin. The shorter are considered to have come from the male.As the age of the embryo increases, these differences between the chromosome mates tend to become less, and it is suggested that at some later period in the history of the animal this difference will entirely disappear in response to the effect of continued existence in a common environment. The length of the chromosomes is very slightly shortened during the early cleavage divisions, while the area of the equatorial cross-section of the cells becomes enormously reduced.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 75
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1927), S. 181-265 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Contains a description of the very involved process of synapsis, which is displayed with unusual clearness in Mecostethus. It is found that the homologous spermatogonial chromosomes, already longitudinally split in the telophase, become closely associated while still in the diatene condition. From the proximal end of each pair, which attaches to the karyotheca, there spins out a delicate thread. Meanwhile the distal, heavy portion of the spiral, double rod executes a loop so that the proximal and distal ends lie near together. Gradually the remaining heavy portion becomes extended until the entire tetrad is in the leptotene condition. In different species of Orthoptera there are variations in the time of association of homologues. The bearing of the facts disclosed in Mecostethus upon the physical characteristics of chromosomes, their movements and changes in meiosis, their individuality and relation to genetical processes are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 76
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In Termopsis nevadensis only soldiers are produced during the first three or four years. When a normal colony comprises approximately twenty inhabitants, the first adult soldier is probably in the fifth instar; the second, somewhat larger, certainly is in the sixth. Later, others are produced in the seventh, and after the reproductive caste becomes differentiated, with about 450 inhabitants, they are in the eighth. Finally, in very old communities, some, at least, are in the ninth. The winged insect invariably is in the eighth.No sign of wings exists until the reproductive caste appears, after which every member of the sixth, and probably the fifth, instar possesses small, yet distinct, wing rudiments. These persist and enlarge in the later stages of the reproductive caste, and, of smaller size, they frequently occur in the soldier nymph and to a less degree in the adult. The third-form adult is probably a sexually mature soldier nymph; the second-form adult seemingly has the same origin and, though possessing wing buds, it does not belong to a special caste.Measurements of scores of recently hatched young disclose no differences other than those of ordinary variation, either in width of head, number of antennal segments, or size of brain and gonad. The first visible signs of caste differentiation appear at a relatively late stage. All of the instars are described in detail and the later ones are compared.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 77
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 217-264 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A description is given of the cytoplasmic alterations in the ovarian egg of Limulus polyphemus leading to the formation of yolk. The nucleolus is found to arise by the confluence of substance which passes from the cytosome into the nucleus, and it is suggested that the chondriosomes, and possibly also the dictyosomes, are derived from an excess of this substance which accumulates in the cytosome. Chondriosomes and dictyosomes are not present in the oogonia, but appear first in oocytes after the formation of the nucleolus is completed.During oogenesis the nucleolus is very active and the greater part of its substance is passed back to the cytosome. By the application of the method of Bell and Doisy for the determination of phosphate in body fluids, the nucleolus is found to be richer in phosphorus than are the other constituents of the cell. The nucleolar emissions effect the transport of phosphorus from the nucleus to the cytosome, where it is used in the synthesis of yolk. The definitive yolk arises by the interaction of nucleolar emissions, chondriosomes, dictyosomes, and ground cytoplasm.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 78
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 341-361 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Conjugating individuals of Metopus sigmoides fuse at the anterior end, the pair presenting the appearance of an inverted letter U. The micronucleus of each conjugant by two successive divisions forms four micronuclei. Three of each four degenerate and the fourth by division forms the pronuclei. Cytoplasm and pronuclei from one conjugant pass over into the other, leaving the old macronucleus and a minimum of cytoplasm behind in the shrunken pellicle of the smaller conjugant, which then separates from the larger one. In the larger exconjugant two pronuclei fuse, forming the functional synkaryon; the two residual pronuclei degenerate and disappear. The synkaryon divides. One of the daughter nuclei condenses into the new micronucleus, the other grows into the new macronucleus. The old macronucleus liquefies and is absorbed. The larger exconjugant, after losing its cilia, secretes a cyst wall about itself and becomes dormant. The whole process requires at least six days for its consummation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 79
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 179 (1984), S. 21-31 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Oogenesis in the silkworm, Bombyx mori, was studied by light and electron microscopy of sections of resin-embedded follicles. The development of the follicles was divided into a series of 12 distinctive stages based on various morphological criteria. Structural changes in the oocyte, nurse cells, and follicle cells are described and illustrated.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 80
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 179 (1984), S. 1-12 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The functional morphology of the male genitalia and the insemination process of Taeniopoda eques were examined using scanning electron microscopy and dissections of mating pairs. Male accessory glands consist of 17 separate tubules belonging to eight categories. Males attach to females via a genital locking mechanism, with special motions of the four aedeagal valves aiding in insertion of the aedeagus. The male passes a series of spermatophores. Each is emptied of its spermatodesm contents, then extracted from the male and female genital tracts through motions of the aedeagal valves, while the pair remain in copulo. This allows the male to keep a strong hold on the female, presumably preventing usurpation by other males, while filling the spermatheca with sperm.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 81
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 179 (1984), S. 33-46 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Yolk formation in the oocytes of the free-living, marine copepod, Labidocera aestiva (order Calanoida) involves both autosynthetic and heterosynthetic processes. Three morphologically distinct forms of endogenous yolk are produced in the early vitellogenic stages. Type 1 yolk spheres are formed by the accumulation and fusion of dense granules within vesicular and lamellar cisternae of endoplasmic reticulum. A granular form of type 1 yolk, in which the dense granules within the cisternae of endoplasmic reticulum do not fuse, appears to be synthesized by the combined activity of endoplasmic reticulum and Golgi complexes. Type 2 yolk bodies subsequently appear in the ooplasm but their formation could not be attributed to any particular oocytic organelle.In the advanced stages of vitellogenesis, a single narrow layer of follicle cells becomes more developed and forms extensive interdigitations with the oocytes. Extra-oocytic yolk precursors appear to pass from the hemolymph into the follicle cells and subsequently into the oocytes via micropinocytosis. Pinocytotic vesicles fuse in the cortical ooplasm to form heterosynthetically derived type 3 yolk bodies.
    Zusätzliches Material: 25 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 82
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 179 (1984), S. 73-93 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The structure of the tooth plates of Protopterus and Lepidosiren was investigated to determine the causes and consequences of postlarval shape change. During growth, the basal area of the tooth plates increases, some cusps become more prominent, and shearing surfaces are sharpened. The jaw articulation restricts the range of movements of the lower jaw, and causes the tooth plates to occlude precisely; the resulting wear patterns are regular. The tooth plates are composed of enamel, trabecular dentine, and petrodentine. A petrodentine column forms the core of a tooth plate; it is flanked by trabecular dentine. Microhardness measurements show that trabecular dentine is comparable in hardness to mammalian dentine, whereas the petrodentine is comparable to enamel. The location and differential wear of these tissues produce the prominent cusps and self-sharpened blades of the adult tooth plates.
    Zusätzliches Material: 29 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 83
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 179 (1984), S. 135-152 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The structure and development of the blood vascular system in the head of the herring gull (Larus argentatus) have been studied using injection techniques and histological sections. Three different but interconnected divisions of the arterial system are recognized in the adult: the cerebral carotid artery system, the external ophthalmic artery system, and the external carotid artery system. Embryologically, the arterial system is characterized by changes in the relative development of these three divisions; the cerebral carotid system being the most prominent in the first half of the embryonic period. The venous system is divided into two parts, the rostral cephalic system and the caudal cephalic system, which drain separate regions of the head. The Rete ophthalmicum, which is an arteriovenous network associated with the external ophthalmic artery system, can be identified from the fifth day of incubation, and its development appears to be coupled with changes in the arterial supply to the eye. The possibility of a homology between the Rete ophthalmicum of birds and the Rete caroticum of mammals is briefly discussed.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 84
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 179 (1984), S. 197-202 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Upon germination of a statoblast, the shell is split into two valves; a mucous pad which represents the basal portion of the body wall of the incipient zooid or ancestrula then appears from between the valves; lastly, a tiny polypide evaginates at the opposite site. When two or more contiguously located statoblasts (floatoblasts or sessoblasts) of the same species germinate simultaneously, their mucous pads often come into contact with each other. The walls of the mucous pads then disappear in the contact areas, thus uniting the coeloms of the ancestrulae. This type of fusion between mucous pads of statoblast-derived ancestrulae was ascertained in Plumatella emarginata, P. repens, P. casmiana, and Hyalinella punctata. The fusion is clearly species specific, and shows no clone specificity or allogeneic recognition. The fusibility test reported here seems to be a useful method for the examination of conspecificity in plumatellid bryozoans.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 85
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 179 (1984), S. 263-271 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The anterior limb bud mesenchyme cells of stage 24 chick embryos were dissociated by trypsinization followed by gentle pipetting, and placed in a tissue culture medium of F12 containing 10% fetal calf serum and antibiotics. As the cells became nearly confluent, some of them were exposed to colchicine or vinblastine sulfate for durations as long as 48 hr. The control and antitubulin-treated cells were processed for transmission electron microscopy and the ultrastructure of the cells was compared. Annulate lamellae (AL) were observed in small amounts in both control and antitubulin-treated cells. The amount of AL did not markedly differ in the control versus antitubulin-treated cells. Furthermore, few multinucleated cells were observed in antitubulin-treated cultures. These results indicate that prolonged culture of cells in antitubulins need not, in itself, lead to a condition of enhanced AL development as reported in several other studies using various cell types.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 86
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 223-242 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The skink, Mabuya multifasciata, torus semicircularis was subdivided into the central (CN), the laminar (LN), and the superficial (SN) nuclei using Golgi and Nissl methods. The central nucleus consisted of small ovoid neurons surrounding a core of fewer large ovoid-triangular and fusiform neurons. The ovoid cells had scant cytoplasm and two to five dendritic trunks. Most of these processes were directed around the periphery of the central nucleus. The large neurons had clumped, darkly staining Nissl substance and a central nucleus. The sparse dendritic spine population on these cells increased distally on the three to five radiate dendrites. The laminar nucleus was present caudal and ventral to the central nucleus. At more rostral levels it was medial and dorsomedial to the central nucleus. The NL had three to five layers of ovoid and fusiform neurons. Scattered within these layers were a few ovoid-triangular neurons. Ovoid neurons had eccentric or central nuclei. The arborization of their dendrites was generally medial and lateral but was frequently oriented caudomedial and rostrolateral. Fusiform neurons had pale Nissl substance, central nuclei, and one to two dendritic processes. The ovoid-triangular neurons had dense, clumped Nissl substance and at least two dendritic trunks with few spines. The superficial nucleus was dorsal, lateral, and caudal to the central nucleus. Extending ventrolaterally around the central nucleus, the superficial nucleus became confluent with the laminar nucleus, ensheathing the central nucleus ventrally, laterally, and dorsally. Rostrally the central nucleus was covered by the layers of the laminar nucleus. Within the superficial nucleus were ovoid, fusiform and sparse ovoid-triangular neurons. The study indicated that the morphology of the torus semicircularis in the golden skink was similar to that in other lizards. This similarity correlates with the degree of development as it relates to the auditory function, but was independent of the type of inner ear restraint mechanism.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 87
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 297-308 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: During the breeding season, male anurans display clasping behavior by holding females with their forelimbs. This behavior is peculiar to males, and may require specializations in forelimb musculature. The present study revealed that five kinds of forelimb muscles were heavier in the male Japanese toad than in the female: the flexor carpi radialis (FCR), the flexor antibrachii medialis caput superius (FAMsup), the abductor indicis longus (AIL), the extensor carpi radialis caput superius (ECRsup), and the flexor antibrachii lateralis superficialis caput superius (FALSsup). In addition, one breast muscle, the coracoradialis (CR), was also heavier in males than in females. A quantitative analysis of muscle fibers processed for myosin ATPase activity showed that, in such “sexually dimorphic muscles” of the female, both fast (twitch) and slow (tonic) muscle fibers were of smaller diameter than in other forelimb muscles of both sexes (all male muscles plus “nondimorphic muscles” of the female). Moreover, both types of fibers were less numerous than in the corresponding muscles of the male. These results suggest that the “sexually dimorphic muscles” are used especially for clasping by the male and are degenerative or subnormal in the female. Slow muscle fibers were neither peculiar to, nor abundant in, these clasping muscles, although they may well be necessary for tonic and prolonged contractions of the forelimb muscles during clasping. The mechanism of sexual dimorphism may be a direct action of androgens on clasping muscles or an indirect action on clasping muscles via the innervating motoneurons.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 88
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984), S. 159-169 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: In the pedicellar segment of the fly antenna there is a large campaniform sensillum. The central projection of the sensory cell (LCC) of this large campaniform sensillum is described from labeling with horseradish peroxidase (HRP) and cobalt. The LCC projects bilaterally to several regions of the brain and subesophageal and thoracic ganglia. The LCC processes in these termination areas were analyzed in relation to other neural processes, including the remaining antennal sensory and motor projection. This analysis was aided by combining HRP labeling with Golgi silver impregnation. Based on earlier findings and the present data we suggest that the LCC, with its various outputs in, e.g., antennal and leg motor centers, serves as a multifunctional sensory path involved in control functions necessary in flight.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 89
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 180 (1984) 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 90
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 181 (1984), S. 97-131 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The three-dimensional structure of the organ of Bellonci in the marine amphipod Gammarus setosus and the relationship between its sensory cells and concretion are described using light, transmission, and scanning electron microscopy, with chemical treatment for cell lysis, calcium chelation, glycogen staining, and lanthanum labelling. The organ is encapsulated and has three units called fuselli. Each is enclosed by two fusellar cells which generate and release calcium granule strands into the cores of the fusellar concretions, which are united in the center of the organ. The surface of each fusellus is traversed by spiral dendrites entering dorsally and ending ventrally. The spiral dendrites arise from sensory neurons contained in a palm-shaped ganglion in the center of the capsule, beyond which they are twisted like a rope before reaching the concretion. The spiral dendrites are linked in pairs by gap and tight junctions and each gives origin to two pairs of 9+0 sensory cilia 30 μm apart. The ciliary distal segments give rise to long tubules which are in contact with the calcium granule strands. The ciliary proximal segments are expanded by many long mitochondria which interdigitate with the branched striated ciliary rootlets. The concretion is suspended in the capsule cavity by axons originating from four neurons of a remote mechanoreceptor. The structure of the organ suggests that it is a sensory organ involved in the reception and integration of a variety of stimuli.
    Zusätzliches Material: 86 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 91
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The fine structure of the kidney and the bladder of the bullfrog (Rana catesbeiana), the bullfrog tadpole, and the mudpuppy (Necturus maculosus) were studied with special attention to the innervation of renal tubule cells and bladder epithelial cells. In the bullfrog kidney, nerve terminals and varicosities were frequently associated with the tubule cells, apparently in an increasing order from the proximal tubule to the connecting tubule. Although these terminals and varicosities did not directly contact the tubular cell membrane, an aggregation of synaptic vesicles on the side facing the tubule was considered as morphological evidence that neurotransmitter can be released here and can affect the transport activity of the tubule cells. The association of nerve varicosities with canaliculi cells in the connecting tubule was also demonstrated. In the bullfrog tadpoles, renal tubule cells were occasionally innervated. In the mudpuppy, renal tubule cells were only poorly innervated. The epithelium of the bullfrog bladder was commonly innervated. Nerve terminals with synaptic vesicles were located very near basal cells and even contacted them directly on rare occasions. In the mudpuppy, the innervation of the bladder epithelium was observed infrequently. The bullfrog tadpoles did not possess an apparent bladder. In all materials studied, renal arterioles and bladder smooth muscle cells were innervated.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 92
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 181 (1984) 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 93
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 181 (1984), S. 239-270 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The mastoid auditory bulla of the extinct marsupial sabertooth, Thylacosmilus, has an enlarged, complex hypotympanic sinus but lacks an alisphenoid contribution. These are marked departures from the usual marsupial condition. Details of the ear region of Thylacosmilus are compared with those of the convergent, extinct placental sabertooth, Smilodon, and each is compared with less specialized related forms to define differences and similarities of the evolutionary paths that led to the striking overall convergence.Functional factors such as pressure transformer ratio (PTR), impedance transformer ratio (ITR), acoustic impedence at the eardrum, and the fraction of the sound energy theoretically transmitted to the inner ear cannot be estimated for Thylacosmilus because certain critical measures are still unknown (tympanum size, ossicle lever arm ratios). However, in both sabertooths enlarged complex hypotympanic sinuses, characterized by expansions and contractions, are greatly developed. They vastly increase middle ear space (volume) and must have influenced these factors. In both, the sinuses provide the large air volume needed to prevent excessive damping of sound energy transmission (Hunt and Korth, '80), and both are believed to have achieved a further modulation of the system from the cushioning or “pillow” effect of the confined air as it directly damps the tympanum itself. Thylacosmilus has still another feature that may have given greater control over damping of sound energy transmission: the direct opening (probably membrane covered) of one of the sinus cavities into the side of the meatal tube. In this feature, as in others noted earlier (Turnbull, '76, '78), we see a greater degree of specialization in this marsupial sabertooth than in a placental counterpart.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 94
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 182 (1984), S. 63-69 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Renal tubules in the dog shark, leopard shark, and red skate were examined histologically and analyzed histochemically for enzymes. Cells of the distal and collecting tubules exhibit extensive interdigitations and large intercellular spaces, suggesting that these tubules are sites of sodium reabsorption. Although Na-K-ATPase is very scarce to nonexistent in the distal and collecting tubules, very intense carbonic anhydrase activity in these segments indicates that they secrete large amounts of hyrogen ion and reabsorb sodium by H+/Na+ exchange process. Epithelial cells of the necks are not interdigitated, tightly join adjacent cells, and have low enzyme activities. They seem to be passively permeable to the water. Necks are attached to the distal tubules with scant intervening stroma. It seems likely that the stroma has a high osmotic pressure resulting from absorption of solutes in the distal tubules. Water may be reabsorbed from necks to stroma because of a concentration gradient of the solutes distributed between these sites.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Light and electron microscopy were used to examine the morphology of the mucosa of the diverticulum, anterior intestine, and transition zone in prefeeding and spontaneously feeding adult lampreys (Petromyzon marinus L.). Absorptive (either types A or B), ciliated, and enteroendocrine cells are present in all regions but the diverticulum and anterior intestine also possess zymogen (secretory) cells. Type A absorptive cells are restricted to the diverticulum and the rostral one-third of the anterior intestine and are characterized by abundant mitochondria and an extensive smooth tubular network. Type B absorptive cells, in the remainder of the anterior intestine and the transition zone, possess small numbers of these organelles but in the transition zone also have inclusion bodies. During feeding, abundant lipid droplets and lipoprotein (VLDL) accumulate in the cytoplasm of both types of absorptive cells and in the lateral intercellular and the perivascular spaces. Lipid is present to a limited extent in ciliated cells and is encountered only rarely in enteroendocrine and zymogen cells. Although the animals are obligate sanguivores, there is little evidence of iron within these mucosal cells. It is suggested that intestinal efficiency displayed by this animal is due in part to ion transport in osmoregulation in type A cells, lipid absorption in types A and B cells, and digestion through enzymes in zymogen cells.
    Zusätzliches Material: 31 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 182 (1984), S. 71-83 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Fourteen species of leiognathid fishes (Perciformes, Leiognathidae) from the Philippine Islands, Thailand, Japan, Indonesia, and Palau were examined for accessory secondary sexual dimorphism. Thirteen species exhibit either external dimorphism (a clear patch of skin on the flanks of males, a large clear patch of skin on the opercular margins of males, or a flank stripe in males) or internal dimorphism (large light organs in males) or both. Eight of the 14 species (and possibly as many as 11) exhibit both forms of sexual dimorphism. Two species show only internal light organ volume dimorphism, and one species shows neither external nor internal dimorphism. Sexual dimorphism is thus very common in leiognathids. The externally dimorphic skin patches are closely associated with the internally dimorphic light organ system in seven species (and possibly as many as ten), indicating a potential for light emission through the clear patches. A bioluminescent signaling function by males is therefore suggested for the sexual dimorphism in leiognathids, which may play an important role in the schooling behavior as well as in species and sexual recognition of these coastal fishes.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 182 (1984), S. 1-37 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Among egg-brooding hylid frogs there is much interspecific variation in the degree of development of the young at hatching. In certain species of Gastrotheca the eggs hatch into free-living tadpoles, whereas in others (and in the genera Amphignathodon, Cryptobatrachus, Stefania and Hemiphractus) the eggs hatch directly into frogs. We examined the oral anatomy of tadpoles and embryos of 22 species of egg-brooding hylids in order to determine the morphological differences between free-living larvae and embryos of species having direct development. All free-living Gastrotheca larvae are morphologically similar and have a large array of oral structures directly associated with a suspension feeding way of life. Among those egg-brooding hylids without free-living larvae there is a complete gradation from those with all of the free-living tadpole oral structures to those with none. Different lineages retain different vestiges of free-living larval morphology, suggesting that direct development has evolved multiple times among these frogs. All of the morphological patterns in the direct-developing embryos can be accounted for by simple truncation or acceleration of the normal tadpole developmental program. We explore the possibility that certain Gastrotheca species with tadpoles may have evolved from species that lack larval stages. The development of oral structures in egg-brooding hylids provides insight into the phylogenetic significance of these charactes in other groups of anurans. Most significantly they reinforce the idea that microhylids evolved from ranoidlike ancestors.
    Zusätzliches Material: 31 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 182 (1984) 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: With the use of rabbit antisera against crustacean hyperglycemic hormone (CHH), it is possible to describe a distinct immunopositive reaction in a group of neurosecretory cells in the medulla terminalis ganglionic X-organ2 (MTGX2), in the MTGX-sinus gland tract, and in a considerable part of the sinus gland from several species of prawns belonging to the Palaemonidae. By introductory studies on the CHH system in Palaemon serratus, we can postulate a sequence in the activity cycle of the CHH-producing cells on the basis of differences in staining intensity of the immunoreaction and such morphometric parameters as cellular and nuclear diameter. By studying the CHH-producing system in combination with variations in the glucose level of the blood, an “inverse relationship” is observed between the number of immunoreactive cells and the blood glucose level during different periods of the year as well as during different stages of the molting cycle. A “shift in phase” of this correlation during the diurnal cycle suggests that several rhythmical phenomena may play a role in the regulation of glycemia in Crustacea.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 182 (1984), S. 115-123 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A large mechanosensory campaniform sensillum (LCS) is found close to the flagellum/pedicellus joint in the antennae of the blowfly Calliphora erythrocephala. The LCS possesses a single sensory cell, enveloping cells and a cuticular stimulus-conducting structure. The distal part of the sensory process is developed as a tubular body and is connected to the two parts of the stimulusconducting apparatus. The sensory cell is characterized by the complete absence of ciliary structures in the transition zone between dendrite and sensory process.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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