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  • Articles  (151)
  • Ultrastructure  (127)
  • Zea
  • Springer  (151)
  • American Institute of Physics
  • Cell Press
  • International Union of Crystallography (IUCr)
  • Oxford University Press
  • 2005-2009
  • 1985-1989  (34)
  • 1975-1979  (117)
  • 1945-1949
  • 2005
  • 1988  (34)
  • 1978  (117)
  • 1946
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  • Articles  (151)
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  • 2005-2009
  • 1985-1989  (34)
  • 1975-1979  (117)
  • 1945-1949
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  • 1
    Electronic Resource
    Electronic Resource
    Coquille de l'oeuf de caille: Étude ultrastructurale et cristallographique (1978)
    Springer
    Calcified tissue international 25 (1978), S. 145-159 
    Details
    ISSN: 1432-0827
    Keywords: Bird egg shell ; Ultrastructure ; Calcification ; Electron diffraction ; Microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The egg-shell of Japanese quail was studied by several techniques. Semithin sections (1μm thick) of non-decalcified shell were observed by normal and polarized light microscopy. Thin sections of non-decalcified shell, examined by transmission electron microscopy, permitted us to observe the forms and dimensions of crystals of calcite within different layers of the shell: mammilary layer, layer of cones, palissade layer and surface crystal layer. There appears to be two distinct zones in the layer of cones as well as in the superficial crystal layer. Electron microdiffraction revealed the orientation of calcite crystals in the columns. Some crystal defects (twins?) were described and the possibility of their artefactual formation during ultramicrotomy is discussed. Localization of Ca, Mg, P and S were made by X-ray microanalysis of semithin sections. This technique shows that shell membranes, and chiefly the true cuticle, are also mineralized but, in these layers, minerals are not crystallized. Otherwise the distribution of Mg is not uniform throughout the shell thickness; it is less concentrated in the external zone of the layer of cones. These results together with observation of developing shells by scanning electron microscopy allowed us to propose a scheme for shell organization of the quail egg. This organization was related with decalcification which occurs during hatching.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010763
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  • 2
    Electronic Resource
    Electronic Resource
    Étude en microscopie électronique et par cytophotométrie à balayage de la structure et de la distribution de la chromatine dans les noyaux des cellules cartilagineuses deTriturus cristatus âgés au cours de la régénération (1978)
    Springer
    Development genes and evolution 184 (1978), S. 195-211 
    Details
    ISSN: 1432-041X
    Keywords: Ultrastructure ; Scanning cytophotometry ; Chromatin ; Chondrocytes ; Regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les cellules cartilagineuses des membres postérieurs deTriturus cristatus en régénération après amputation, ont été étudiées en microscopie électronique et par cytophotométrie à balayage. Nous nous sommes intéressés à la structure et à la distribution de la chromatine mais aussi à différents organites cytoplasmiques. Dans l'étude de cytophotométrie à balayage, la chromatine a été considérée à travers son constituant majeur, l'ADN, coloré par la réaction de Feulgen. Au cours de la régénération du membre, l'hétérochromatine initialement condensée, essentiellement accolée à la membrane nucléaire se décondense. Les vacuoles du cytoplasme, caractéristiques des animaux âgés par rapport aux animaux jeunes, disparaissent, les mitochondries et le reticulum endoplasmique rugueux deviennent plus abondants. Les caractéristiques nucléaires de l'activation cellulaire apparaissent précocement, précédent les modifications cytoplasmiques et conduisent à des cellules en tous points identiques aux cellules d'animaux jeunes en dehors de tout processus régénératif. Cette phase d'euchromatisation et de restructuration cytoplasmique est peut-être nécessaire à l'accroissement d'activité métabolique et à la division cellulaire qui suivent. Son déroulement peut expliquer tout au moins le ralentissement de la régénération observé chez les animaux âgés par rapport aux animaux jeunes.
    Notes: Summary Cartilaginous cells of aged newts (Triturus cristatus) were studied during hind limb regeneration. The electron microscope was used to study the structure and distribution of chromatin in the cell nuclei, while the DNA content of the chromatin was measured by means of a scanning cytophotometer. Changes in the ultrastructure of the cytoplasm during regeneration were also studied. It was observed that the structure and distribution of chromatin in the activated cell is greatly modified. In the non-activated cell of the aged newt, the chromatin is found highly condensed and distributed peripherally close to the nuclear membrane. In contrast, in the activated cells, the chromatin is much less condensed and is distributed throughout the nucleus. Moreover, cytoplasmic vacuoles, found only in the non-activated aged cells, disappear and an increase in the mitochondria and rough endoplasmic reticulum is also observed. Changes in the nuclear structure are observed prior to the cytoplasmic modifications. It is interesting to note that the process of activation induces structural changes in the aged cells which make these cells appear to be structurally identical to the young cells. This process of rejuvenation takes 3–5 days in the newt. We suggest that these structural changes of the chromatin and cytoplasm in the aged cells are necessary to increase the metabolic activity which precedes cell division. It may also explain why regeneration takes a longer time in the aged animals than in the young ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848254
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  • 3
    Electronic Resource
    Electronic Resource
    Retention of the differentiated state by larvalXenopus liver cells in primary culture (1978)
    Springer
    Development genes and evolution 185 (1978), S. 235-248 
    Details
    ISSN: 1432-041X
    Keywords: Liver ; Primary culture ; Ultrastructure ; Albumin synthesis ; Xenopus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Electron microscopic analysis of primary cultures derived from larvalXenopus liver has shown that these cells, although they form only two-dimensional aggregates, retain and presumably also develop structural characteristics typical of liver parenchyma cells, such as bile canaliculi with microvilli and epithelial junctional complexes. As judged from structural criteria, primary cultures contain 80–90% hepatocytes. In contrast to the intact tissue, primary cultures showed excessive development of microfilaments, however. Incorporation of labeled amino acids has revealed further that the capacity for protein synthesis is maintained in culture and that synthesis of liverspecific protein albumin is maintained in vitro, even in liver cultures derived from thyrostatic tadpoles. This latter result suggests that initiation of albumin synthesis in the larval liver is probably not dependent upon thyroid hormones but rather reflects the protodifferentiated state of this tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00848354
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  • 4
    Electronic Resource
    Electronic Resource
    Ultrastructure, histology, and innervation of the mantle edge of the freshwater pulmonate snailsLymnaea stagnalis andBiomphalaria pfeifferi (1978)
    Springer
    Calcified tissue international 26 (1978), S. 271-282 
    Details
    ISSN: 1432-0827
    Keywords: Shell formation ; Free nerve endings ; Ultrastructure ; Lymnaea stagnalis ; Biomphalaria pfeifferi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The mantle edge of the freshwater pulmonate snailsLymnaea stagnalis andBiomphalaria pfeifferi was investigated with histochemical and ultrastructural methods. The mantle edge gland, which is involved in shell formation, consists of the periostracal groove and the belt. This belt appears to be composed of various regions. In the area of the periostracal groove a number of subepithelial gland cell types occur; these release their products into the groove. Between the groove cells ciliated free nerve endings terminate; the corresponding perikarya occur in the subepidermal connective tissue. Also in the posterior belt region free nerve endings were observed between the epithelial cells; in addition, a particular type of subepithelial gland cell was found in this area. The epithelial cells of this part of the belt have the ultrastructural characteristics of ion and water transporting cells; they are probably involved in calcium deposition and resorption. The possible role of the free nerve endings and of the subepithelial gland cells is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02013270
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  • 5
    Electronic Resource
    Electronic Resource
    A comparison of regenerated cell walls in tobacco and cereal protoplasts (1978)
    Springer
    Planta 139 (1978), S. 155-158 
    Details
    ISSN: 1432-2048
    Keywords: Avena ; Cell-wall regeneration ; Electrical potential ; Nicotiana ; Protoplast culture ; Turgor pressure ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four independent kinds of observations indicate that the cell wall regenerated by oat (Avena sativa L.) and corn (Zea mays L.) protoplasts in culture is less well developed than that regenerated by tobacco (Nicotiana tabacum L.) protoplasts. Following wall regeneration the cereal protoplasts remained susceptible to osmotic shock upon transfer to water, showed great enlargement, stained poorly with calcofluor white, and maintained a positive internal electrical potential. The development of a negative membrane potential by tobacco protoplasts in culture often occurred simultaneously with the onset of cell division. Since division was observed only in protoplasts which had regenerated good cell walls and had re-established negative membrane potentials it is suggested that culture conditions which favor these two processes should improve protoplast viability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387141
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  • 6
    Electronic Resource
    Electronic Resource
    Properties of auxin binding sites in different subcellular fractions from maize coleoptiles (1978)
    Springer
    Planta 140 (1978), S. 97-106 
    Details
    ISSN: 1432-2048
    Keywords: Auxin binding ; Coleoptiles ; Multiple receptors ; Tonoplast ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In-vitro binding of labeled auxins to sedimentable particles was tested in subcellular fractions from homogenates of maize (Zea mays L.) coleoptiles. The material was fractionated by differential centrifugation or on sucrose density gradients. It was confirmed that the major saturable binding activity (site I) for 1-naphthyl[1-14C]acetic acid is associated with vesicles derived from the endoplasmatic reticulum. A second type of specific auxin binding (site II) could be distinguished by several criteria, e.g. by the low affinity towards phenylacetic acid. The particles carrying site II could be clearly separated from markers of the endoplasmatic reticulum, the plasmalemma, the mitochondria and the nuclei, while their density as well as sedimentation velocity correlated with particle-bound acid phosphatase, indicating a localization at the tonoplast. In contrast to site I, binding at site II was hardly affected by a supernatant factor and by sulfhydryl groups. However, the specificity pattern of site II towards auxins and auxin analogs was very similar to that of site I tested in the presence of supernatant factor. The existence of a third auxin receptor localized in plasma membrane-rich gradient fractions was indicated by a preferential in-vitro binding of 2,4-dichlorophenoxyacetic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384907
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  • 7
    Electronic Resource
    Electronic Resource
    Continuous measurement of initial curvature of maize coleoptiles induced by lateral auxin application (1978)
    Springer
    Planta 140 (1978), S. 201-211 
    Details
    ISSN: 1432-2048
    Keywords: Auxin ; Cell elongation ; Coleoptiles ; Fusicoccin ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To analyze early effects of auxin application, an apparatus was developed which continuously and simultaneously registered the curvature of 10 individual maize (Zea mays L.) coleoptiles. Resolution was less than 5 μm over a range of ±0.5 mm. The data were evaluated and plotted via paper tape and Hewlett-Packard-computer. Unilateral application of 3×10-5 M indoleacetic acid (IAA) resulted in a transient inhibition of growth on the side of application for ca. 10 min (Phase I), followed by a strong stimulation (Phase II). The phytotoxin fusicoccin (FC) caused an immediate stimulation of elongation. The initial negative reaction of Phase I is auxin-specific. Only active auxins such as IAA and 1-naphtaleneacetic acid produced this initial inhibition; chemical analogs-inhibitory or neutral in long-term growth tests, e.g. phenylacetic acid-did not show any significant effects on Phase I. When the coleoptiles were symmetrically preloaded with different levels of auxin, only a large step-up of subsequent unilateral auxin application resulted in a negative phase I; a small step-up led to an immediate positive reaction. The results are discussed in context with the parallel kinetics for various other auxin-induced reactions of coleoptile cells which have already been published.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390249
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  • 8
    Electronic Resource
    Electronic Resource
    Light-induced fluorescence decay during the greening of normal and lincomycin-treated maize leaves (1978)
    Springer
    Planta 141 (1978), S. 135-139 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll (fluorescence) ; Fluorescence (chlorophyll) ; Lincomycin ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Light-induced fluorescence decay was examined during the greening of control and lincomycintreated maize (Zea mays L.) leaves. Assuming that this decay to a first approximation is the result of two parallel first-order reactions, the fluorescence induction curves were linearized on the logarithm plot and the parameters were determined. The variable fluorescence increased, and the parameters of the two linear sections of the fluorescence decay—that is, the kinetics of the induction curves—changed during the greening of the control leaves. Lincomycin treatment caused some chlorophyll deficiency and the lowering of the chlorophyll a/b ratio, changed the fluorescence emission spectra and the effect of Mg2+ on the regulation of the excitation energy distribution. The structure of the thylakoids and the kinetics of the fluorescence decay were also changed in the treated leaves. The possible relationship between the change of the kinetics of the fluorescence decay and the change of spillover during greening and after lincomycin treatment is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387879
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  • 9
    Electronic Resource
    Electronic Resource
    Changes in the secretory activity of the Golgi apparatus during the cell cycle in root tips of maize (Zea Mays L.) (1978)
    Springer
    Planta 138 (1978), S. 113-118 
    Details
    ISSN: 1432-2048
    Keywords: Cell division ; Cell wall ; Golgi apparatus ; Secretory vesicles ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Epidermal cells of maize roots were studied to determine the distribution of Golgi apparatus-derived secretory vesicles in various stages of cell division. The following conclusions were reached: 1) The pattern of Golgi apparatus secretion varies with the cell cycle. 2) Large numbers of secretory vesicles are incorporated into the cell plate. 3) Secretory vesicles from the Golgi apparatus are incorporated primarily in walls undergoing expansion. 4) Secretory vesicles are smaller during mitosis and the first part of cytokinesis than they are during interphase. 5) Secretory vesicles account for at least 12–23% of cell-plate plasma membrane and an estimated 25% of cell-plate volume.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391165
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  • 10
    Electronic Resource
    Electronic Resource
    α-and β-Glycosidases in maize roots (1978)
    Springer
    Planta 138 (1978), S. 119-122 
    Details
    ISSN: 1432-2048
    Keywords: Glycosidases ; Root ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four glycosidases were analyzed in 10 mm apical segments prepared from growing roots (15 mm) of Zea mays L. The pH optima were found to be 5.8 for β-glucosidase, 4.4 for β-galactosidase, 6.4 for α-glucosidase and 6.0 for α-galactosidase. The β-glucosidase showed 4-fold higher activity than the β-galactosidase. The distribution of the β-glucosidase activity was signifcantly different from that of the β-galactosidase, α-glucosidase and α-galactosidase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391166
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  • 11
    Electronic Resource
    Electronic Resource
    3-O-Methyl glucose uptake stimulation by auxin and by fusicoccin in plant materials and its relationships with proton extrusion (1978)
    Springer
    Planta 138 (1978), S. 249-256 
    Details
    ISSN: 1432-2048
    Keywords: Auxin ; Fusicoccin ; Glucose transport ; Proton flux ; Roots ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Auxin and fusicoccin (FC) stimulate the active uptake of 3-O-methyl glucose (3-O-MG) in those materials in which they have been shown to activate an electrogenic proton extrusion (Pisum sativum L. stems, Zea mays L. coleoptiles and roots). In maize roots the curve relating 3-O-MG influx to external concentrations indicated that the values of the apparent Km increase in the 3-O-MG concentration range between 2×10-5 mol l-1 and 2×10-2 mol l-1. FC did not alter the Km values and its stimulating effect was nearly constant at all 3-O-MG concentrations tested. Basal and FC-induced uptake of 3-O-MG appeared associated with a transient proton influx suggesting that also in maize roots a sugar-proton contransport occurs. Diethyl stilbestrol, which inhibits proton extrusion, inhibited also basal and FC-induced 3-O-MG uptake. The data support the view that the stimulation by FC of 3-O-MG uptake is closely related to that of proton extrusion. The stimulation by FC of 3-O-MG uptake cannot be replaced by increasing extracellular proton concentration, nor may be explained only by the FC-induced hyperpolarization of transmembrane potential difference. The hypothesis is proposed that the effect of FC on 3-O-MG uptake depends on an increase of cytoplasmic pH, following the activation of the proton extruding system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386819
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  • 12
    Electronic Resource
    Electronic Resource
    Auxin gradient along the root of the maize seedling (1978)
    Springer
    Planta 141 (1978), S. 179-181 
    Details
    ISSN: 1432-2048
    Keywords: Auxin ; Maize ; Root tip ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract [5-3H]Indol-3yl-acetic acid (IAA) applied to the shoot apices of intact 6-day-old maize (Zea mays L.) plants moved into the primary root and accumulated at the root apex. IAA from the shoot could partially satisfy the requirement of the primary root for IAA for growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387886
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  • 13
    Electronic Resource
    Electronic Resource
    Identification of embryonal antigens of maize: Globulins as primary reserve proteins of the embryo (1978)
    Springer
    Planta 143 (1978), S. 11-20 
    Details
    ISSN: 1432-2048
    Keywords: Antigen spectra ; Embryo (proteins) ; γ-Plantlets ; Germination (seeds) ; Globulins ; Proteins (storage) ; Seedling growth ; Storage proteins ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Normal and γ-irradiated caryopses of Zea mays L. were germinated, and the degradation of embryonal antigens (EA) was followed in the endosperms, scutella and embryonic axes of the seedlings, using double immunodiffusion, immunoelectrophoresis and quantitative immunoprecipitation. The predominant transient EA were presumed to be storage proteins related to the reserve globulins of dicotyledonous seeds. Therefore globulins were isolated from maize scutella, purified by (NH4)2SO4 fractionation and isoelectric precipitation, and the molecular weights of the polypeptide units were estimated by discontinuous sodium-dodecyl-sulphate slab electrophoresis. The globulins were found to be identical with the predominant EA and amounted to about 40% of the protein nitrogen in the embryos of mature, non-germinated caryopses. The presumed reserve function of the globulins and the characteristic time course of their degradation in embryonic axes and scutella of maize seedlings are discussed in relation to the two-step pattern of mobilization of nitrogen reserves in germinating cereal caryopses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00389046
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  • 14
    Electronic Resource
    Electronic Resource
    Studies of chloroplast development in four maize mutants defective in chlorophyll biosynthesis (1978)
    Springer
    Planta 143 (1978), S. 207-211 
    Details
    ISSN: 1432-2048
    Keywords: Chlorophyll mutants ; Chloroplasts (development) ; Etioplasts ; Prolamellar body ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four mutants of maize (Zea mays L.) defective in chlorophyll biosynthesis have been analyzed with regard to the sites of their lesions and their effects on chloroplast development. Two yellow mutants, which accumulate no detectable porphyrin precursors when grown in darkness, are defective in the conversion of protoporphyrin IX to magnesium protoporphyrin. Etioplasts of these mutants may develop elaborate lamellar membrane systems, but prolamellar bodies are never observed. Two mutants, which are necrotic when grown under illumination, develop normal (non-necrotic) leaf tissue in the dark and accumulate a small amount of magnesium protoporphyrin monomethyl ester, corresponding approximately to the amount of protochlorophyllide accumulated by normal plants. The etioplasts of these mutants contain noncrystalline bodies. The implications of these observations with respect to chloroplast development are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387791
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  • 15
    Electronic Resource
    Electronic Resource
    Lateral electrical potential following asymmetric auxin application to maize coleoptiles (1978)
    Springer
    Planta 140 (1978), S. 31-35 
    Details
    ISSN: 1432-2048
    Keywords: Auxin ; Coleoptiles ; Electrical Potential ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Following asymmetric application of indoleacetic acid to maize (Zea mays L.) coleoptiles the early time course of changes in lateral electrical potential was externally monitored with static-drop electrodes. First, an early negative potential change of ca.-1 mV was measured at the surface on the side of a strong auxin application. This negative auxin effect ended after ca. 15 min and was followed by a strong and lasting auxin stimulation of a positive lateral potential up to +12 mV at the auxin-treated side. The initial auxin effect appeared to depend on the size of the step-up in auxin concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00389376
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  • 16
    Electronic Resource
    Electronic Resource
    Patterns of proteolytic enzyme activities in different tissues of germinating corn (Zea mays L.) (1978)
    Springer
    Planta 140 (1978), S. 155-162 
    Details
    ISSN: 1432-2048
    Keywords: Aminopeptidases ; Carboxypeptidases ; Endopeptidases ; Germination (seeds) ; Proteases ; Seedling development ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Profiles of pH dependence and activities of live proteolytic enzymes, amino- and carboxypeptidase and endopeptidases active at pH 3.8, 5.4 and 7.5, with casein as substrate, were determined in crude extracts from the various organs of corn seedlings during germination and early development (30°C, dark, 8 d). With respect to the endopeptidases, caseolytic activities at pH 3.8, 5.4 and 7.5 in extracts from endosperm increased concurrently with loss of endosperm N during germination; however, the relative amounts of the pH 7.5 activity were very small. In scutellum extracts, caseolytic activities at both pH 5.4 and 7.5 increased during the initial stages of development but only the increase at pH 5.4 was concurrent with loss of scutellar N. In shoot extracts, caseolytic activities at pH 5.4 and 7.5 were very low and remained relatively constant. There was a progressive increase in shoot N with time. In root extracts, caseolytic activities at pH 5.4 and 7.5 were higher (3-fold) than in shoot extracts. The activity at pH 5.4 remained constant while the activity at pH 7.5 increased during germination. The rate of accumulation of N by the root was low after day 5. The pattern and ratio but not the amounts of the pH 5.4 and 7.5 caseolytic activities of the root were similar to those observed in senescing leaves of field-grown corn. Addition of mercaptoethanol increased (several-fold) the caseolytic activities at pH 3.8 and 5.4, especially the latter, but not the pH 7.5 activity in endosperm extracts and increased the pH 5.4 activity in extracts from scutellum (30%) and roots (30%) while the effect in shoot extracts was negligible. Carboxypeptidase activity was relatively low in young tissue (root tip, 3-d-old shoots) and increased with development of the various organs except the roots (whole) where the activity remained relatively constant. The increases in carboxypeptidase activities were concurrent with decreases in N from endosperm and scutellum; this result indicates that this enzyme in these tissues may be involved (cooperatively with endopeptidases) in the mobilization of reserve protein. Of all the enzymes tested, only carboxypeptidase activity was markedly (in excess of 50%) inhibited by phenylmethylsulfonylfluoride. Only aminopeptidase activity was found in appreciable amounts in endosperm and scutellum of dry kernels. Aminopeptidase activity was highest in organs with high metabolic activity (scutella, shoot, root tips) and decreased in plant parts undergoing rapid loss of nitrogen (endosperm, senescing leaves).
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    URL: http://dx.doi.org/10.1007/BF00384915
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  • 17
    Electronic Resource
    Electronic Resource
    Characterization of ribonucleic acid synthesis by nuclei isolated from Zea mays (1978)
    Springer
    Planta 144 (1978), S. 89-93 
    Details
    ISSN: 1432-2048
    Keywords: Nuclei ; RNA polymerase ; RNA synthesis (in vitro) ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nuclei were isolated from the shoots of Zea mays and assayed for endogenous RNA polymerase activity in vitro. Maximum incorporation from radioactive precursors (70 pmol [3H]uridine 5′ monophosphate/100 μg DNA) was reached after incubation for 1 h at 25°C. The RNA product, analysed by polyacrylamide gel electrophoresis, was polydisperse in size with an upper limit of 2x106 daltons. Discrete peaks of rRNA were not detected, probably because of endogenous ribonuclease activity. The inclusion of α-amanitin (4 μg/ml) in the incubation reduced the total incorporation by approximately 40% but did not significantly alter the size of the RNA product. Although 40% of the total activity could be attributed to RNA polymerase II, [3H]RNA synthesised in vitro was found not to contain long sequences of poly (A).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385012
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  • 18
    Electronic Resource
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    Photosynthetic carbon metabolism during leaf ontogeny in Zea mays L.: Enzyme studies (1978)
    Springer
    Planta 142 (1978), S. 269-274 
    Details
    ISSN: 1432-2048
    Keywords: Carboxylases ; Leaf development ; Photosynthesis (C4) ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The activities of several enzymes, including ribulose-1,5-diphosphate (RuDP) carboxylase (EC 4.1.1.39) and phosphoenolpyruvate (PEP) carboxylase (EC 4.1.1.31) were measured as a function of leaf age in Z. mays. Mature leaf tissue had a RuDP-carboxylase activity of 296.7 μmol CO2 g-1 fresh weight h-1 and a PEP-carboxylase activity of 660.6 μmol CO2 g-1 fresh weight h-1. In young corn leaves the activity of the two enzymes was 11 and 29%, respectively, of the mature leaves. In senescent leaf tissue, RuDP carboxylase activity declined more rapidly than that of any of the other enzymes assayed. On a relative basis the activities of NADP malic enzyme (EC 1.1.1.40), aspartate (EC 2.6.1.1) and alanine aminotransferase (EC 2.6.1.2), and NAD malate dehydrogenase (EC 1.1.1.37) exceeded those of both PEP and RuDP carboxylase in young and senescent leaf tissue. Pulse-chase labeling experiments with mature and senescent leaf tissue show that the predominant C4 acid differs between the two leaf ages. Labeling of alanine in senescent tissue never exceeded 4% of the total 14C remaining during the chase period, while in mature leaf tissue alanine accounted for 20% of the total after 60 s in 12CO2. The activity of RuDP carboxylase during leaf ontogeny in Z. mays parallels the development of the activity of this enzyme in C3 plants.
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    URL: http://dx.doi.org/10.1007/BF00385076
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    Naturally occuring modifiers of auxin-receptor interaction in corn: Identification as benzoxazolinones (1978)
    Springer
    Planta 142 (1978), S. 103-107 
    Details
    ISSN: 1432-2048
    Keywords: Auxin ; Benzoxazolinones ; Receptors ; Supernatant factor ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A naturally-occurring material termed ‘supernatant factor’ [Ray, P.R., Dohrmann, U., Hertel, R.: Plant Physiol. 59. 357–364 (1977)], which has the property of modifying the binding affinity of auxins to receptor sites, has been isolated from corn (Zea mays L.) and characterised as a mixture of 6-methoxy-2-benzoxazolinone (MBOA) and 6,7-dimethoxy-2-benzoxazolinone (DMBOA). DMBOA is about 50 times more active than MBOA in inhibiting binding of the auxin 1-naphthylacetic acid to membrane-bound or solubilised receptors. The activity of these compounds and the parent analogue in inhibiting auxin binding is correlated with their ability to inhibit auxin-induced growth.
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    URL: http://dx.doi.org/10.1007/BF00385127
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    Spectral dependence of the light-induced geotropic response in Zea roots (1978)
    Springer
    Planta 142 (1978), S. 275-279 
    Details
    ISSN: 1432-2048
    Keywords: Geotropism ; Light and geotropism ; Root geotropism ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The induction by light of geotropic responsiveness in the primary roots of Zea mays L. (cv. Golden Cross Bantam 70) was found to be governed by the “all-or-none law”. The response was induced by light energies above a threshold value, but the maximal curvature of geo-stimulated roots was constand irrespective of the light energy above that threshold. The action spectrum for this light effect showed a large peak at 650, a small peak at 410, and a shoulder at 663 nm. The effect of red light was not reversed by far-red light. Thus, the geotropic response in Zea roots may not be controlled by phytochrome.
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  • 21
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    Rapid, localized light effect on root growth in maize (1978)
    Springer
    Planta 144 (1978), S. 109-110 
    Details
    ISSN: 1432-2048
    Keywords: Growth (roots) ; Light and root growth ; Root cap ; Root growth ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method using optical microfibers permitted localized exposure of the cap or the elongating part of growing maize (Zea mays L.) roots to white light. When the cap was illuminated, a strong and very rapid inhibition of the elongation rate of the roots was found. When the light microbeam was directed at the elongating region, the roots continued to grow at the same rate as before the illumination.
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    URL: http://dx.doi.org/10.1007/BF00385015
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  • 22
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    Leaf structure in relation to solute transport and phloem loading in Zea mays L. (1978)
    Springer
    Planta 138 (1978), S. 279-294 
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    ISSN: 1432-2048
    Keywords: Apoplast ; Companion cell-sieve tube complex ; Leaf structure ; Phloem loading ; Sieve tubes ; Symplast ; Vascular bundle ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Small and intermediate (longitudinal) vascular bundles of the Zea mays leaf are surrounded by chlorenchymatous bundle sheaths and consist of one or two vessels, variable numbers of vascular parenchyma cells, and two or more sieve tubes some of which are associated with companion cells. Sieve tubes not associated with companion cells have relatively thick walls and commonly are in direct contact with the vessels. The thick-walled sieve tubes have abundant cytoplasmic connections with contiguous vascular parenchyma cells; in contrast, connections between vascular parenchyma cells and thin-walled sieve tubes are rare. Connections are abundant, however, between the thin-walled sieve tubes and their companion cells; the latter have few connections with the vascular parenchyma cells. Plasmolytic studies on leaves of plants taken directly from lighted growth chambers gave osmotic potential values of about-18 bars for the companion cells and thin-walled sieve tubes (the companion cell-sieve tube complexes) and about-11 bars for the vascular parenchyma cells. Judging from the distribution of connections between various cell types of the vascular bundles and from the osmotic potential values of those cell types, it appears that sugar is actively accumulated from the apoplast by the companion cell-sieve tube complex, probably across the plasmalemma of the companion cell. The thick-walled sieve tubes, with their close spatial association with the vessels and possession of plasmalemma tubules, may play a role in retrieval of solutes entering the leaf apoplast in the transpiration stream. The transverse veins have chlorenchymatous bundle sheaths and commonly contain a single vessel and sieve tube. Parenchymatic elements may or may not be present. Like the thick-walled sieve tubes of the longitudinal bundles, the sieve tubes of the transverse veins have plasmalemma tubules, indicating that they too may play a role in retrieval of solutes entering the leaf apoplast in the transpiration stream.
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    URL: http://dx.doi.org/10.1007/BF00386823
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    Pre-fertilization degeneration of both synergids in Brassica campestris ovules (1988)
    Springer
    Sexual plant reproduction 1 (1988), S. 208-216 
    Details
    ISSN: 1432-2145
    Keywords: Megagametophyte ; Synergids ; Brassica campestris ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Brassica campestris, both synergids of the ovule degenerate before the arrival of the pollen tube. Synergid degeneration does not depend on pollination. At the non-degenerated stage, the synergids are completely filled with a complexly organized cytoplasm containing numerous mitochondria with many cristae, a large number of dictyosomes with many associated vesicles, and a very extensive rough endoplasmic reticulum. The degenerative changes that occur in the cytoplasm of the synergids are characterized by a loss of visibility of the membranes of the endoplasmic reticulum and the simultaneous formation of dense deposits on the surrounding membranes of the mitochondria. Locally, the plasma membranes of the synergids disappear, and some ground plasma of the synergids penetrates into the space between the plasma membranes of the egg cell and the central cell.
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    URL: http://dx.doi.org/10.1007/BF00189154
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    The bound auxins: Protection of indole-3-acetic acid from peroxidase-catalyzed oxidation (1978)
    Springer
    Planta 139 (1978), S. 203-208 
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    ISSN: 1432-2048
    Keywords: Auxin (bound) ; Auxin oxidation ; IAA oxidase ; Peroxidase ; Pisum ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Indole-3-acetic acid (IAA) was oxidized by horseradish peroxidase, but ester and amide conjugates of IAA were not degraded. Addition of indoleacetyl-myo-inositol, indoleacetyl-L-aspartate, indoleacetylglycine, indoleacetyl-L-alanine, indoleacetyl-D-alanine, or indoleacetyl-β-alanine did not affect the rate of oxidation of IAA by horseradish peroxidase. Peroxidase preparations from Pisum sativum L. and Zea mays L. behaved similarly in that they rapidly oxidized IAA, but not conjugates found in the plant from which the peroxidase was prepared. These results indicate that conjugation could affect the stability of IAA in vivo.
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    URL: http://dx.doi.org/10.1007/BF00388631
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    Oxygen inhibition of photosynthesis (1978)
    Springer
    Planta 140 (1978), S. 1-6 
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    ISSN: 1432-2048
    Keywords: Leaf temperature ; Oxygen (photosynthesis) ; Photosynthesis ; Temperature (photosynthesis) ; Triticum ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of leaf temperature, O2 and calculated O2/CO2 solubility ratio in the leaf on the quantum yield of photosynthesis was studied for the C4 species, Zea mays L., and the C3 species, Triticum aestivum L. Over a range of leaf temperatures of 16 to 35° C, the quantum yield of Z. mays was relatively constant and was similar under 1.5 and 21% O2, being ca. 0.059 mol CO2 mol-1 quanta absorbed. Under 1.5% O2 and atmospheric levels of CO2, the quantum yield of T. aestivum was relatively constant (0.083 mol CO2 mol-1 quanta absorbed) at leaf temperatures from 15 to 35° C. Atmospheric levels of O2 (21%) reduced the quantum yield of photosynthesis in T. aestivum and as leaf temperature increased, the quantum yield decreased from 0.062 at 15°C to 0.046 mol CO2 mol-1 quanta absorbed at 35°C. Increasing temperature decreases the solubility of CO2 relatively more than the solubility of O2, resulting in an increased solubility ratio of O2/CO2. Experimentally manipulating the atmospheric levels of O2 or CO2 to maintain a near-constant solubility ratio of O2/CO2 at varying leaf temperatures largely prevented the temperature-dependent decrease in quantum yield in t. aestivum. Thus, the decrease in quantum yield with increasing leaf temperature in C3 species may be largely caused by a temperaturedependent change in the solubility ratio of O2/CO2.
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    URL: http://dx.doi.org/10.1007/BF00389372
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    Disappearence of the intracytoplasmic membranes inRhodopseudomonas sphaeroides (1978)
    Springer
    Archives of microbiology 117 (1978), S. 293-295 
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    ISSN: 1432-072X
    Keywords: Rhodopseudomonas sphaeroides ; Intracytoplasmic membranes ; Membranes ; Ultrastructure ; Bacteriochlorophyll ; Chromatophores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photosynthetic bacterium,Rhodopseudomonas sphaeroides, can be grown phototrophically (light, anaerobiosis), of chemotrophically (dark, aerobiosis). In the first case, it contains intracytoplasmic membranes with photosynthetic pigments. When shifted from phototrophy to chemotrophy these membranes disappear in an unknown fashion. In the present experiment, samples were taken for electron microscopy, cell density and bacteriochlorophyll determinations after shift from phototrophy to chemotrophy. The density of intracytoplasmic vesicles was measured on micrographs. During the first 2h growth is very slow and the ultrastructure remains unaltered. As growth resumes, the vesicles disappear at a rate which implies that they are not incorportated into the cytoplasmic membrane, nor actively digested, but remain intact and become increasingly diluted in the cytoplasm as the culture grows. The size of the vesicles was estimated to about 500 Å. The number of vesicles in phototrophically grown cells was calculated to about 575 per cell, and after 6h chemotrophic growth to about 100. The areas of the cytoplasmic and intracytoplasmic membranes are roughly calculated.
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    Sporogenesis in Streptomyces melanochromogenes (1978)
    Springer
    Archives of microbiology 118 (1978), S. 309-316 
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    ISSN: 1432-072X
    Keywords: Streptomyces melanochromogenes ; Sporogenesis ; Formation of sporulation septum ; Delimitation, separation, and release of spores ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mode of spore differentiation in a strain of Streptomyces melanochromogenes was followed by analysis of ultrathin sections of sporulating aerial hyphae at various stages of sporogenesis. A special accent was laid on the formation of the sporulation septum and its alterations in the course of spore delimitation and separation. Distinct differences in formation and substructure have been observed between the cross walls of vegetative hyphae and the sporulation septa. Cross walls of vegetative hyphae are formed in a way typical for Gram-positive bacteria by a centripetal annular ingrowth of cytoplasmic membrane, on which wall material immediately is deposited. The development of the sporulation septa is characterized by the accumulation of amorphous material in addition to the newly synthesized wall layer inside the invaginating cytoplasmic membrane. This amorphous septal material will later be decomposed presumably by two lytic systems which cause the separation of the spores. The central region of the finished sporulation septum is perforated by microplasmodesmata. Spores are released by a break down of the surface sheath. The complete spores are enveloped by a twolayered cell wall and the spiny surface sheath.
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    URL: http://dx.doi.org/10.1007/BF00429123
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    Ultrastructural study of microcyclic macroconidiation in Neurospora crassa (1978)
    Springer
    Archives of microbiology 116 (1978), S. 279-288 
    Details
    ISSN: 1432-072X
    Keywords: Neurospora crassa ; Macroconidia ; Microcycle ; Heat ; Ultrastructure ; Nucleolus ; Proconidia ; Septa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Heat-shock of macroconidia of Neurospora crassa at 46°C followed by shift-down to 25°C determines premature conidiogenesis. The nuclei and cytoplasm of heat-treated, swollen conidia contain spots of a dense material especially concentrated around the nucleolus in short time treated ones. In the first proconidium apically budding on the enlarged tip of the premature conidiophore, small vesicles are peripherally spread. A few such vesicles are later seen lining the initially simple septum separating the proconidial units into conidia. The doubling of this interconidial septum is surface viewn as a thick annulus. Disarticulation of the conidial units intervenes along a septal furrow of electroluscent material. Interconidial continuity through the septal pores is transiently insured by a connective which is ruptured for final liberation of the conidia.
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    Ultrastructural and cytochemical examination of the nuclear crystalloid inclusions of Olea europaea L. mesophyll cells (1988)
    Springer
    Trees 2 (1988), S. 261-266 
    Details
    ISSN: 1432-2285
    Keywords: Nuclear crystalloid inclusions ; Olea europaea ; Cytochemistry ; Ultrastructure ; Glycoprotein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The nuclei of mesophyll cells of olive trees contain numerous sizeable crystalloid inclusions. Cytochemical examination using epoxy resin-embedded, semithin-sectioned tissue indicated the presence of proteins and oligoor polysaccharides in these inclusions. Their electron microscopical analysis revealed a crystalline substructure consisting of intersected subunits of high order. The spacing of the lattice fibrils and the angles of intersection were determined and used to establish a model of the unit cell of crystallization. It is suggested that the nuclear crystalloids of olive trees consist of glycoprotein molecules. They differ from the intranuclear crystalloids observed in other species predominantly in the high density of their subunit arrangement.
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    URL: http://dx.doi.org/10.1007/BF00202381
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    Effects of fusicoccin on the activity of a key pH-stat enzyme, PEP-carboxylase (1978)
    Springer
    Planta 139 (1978), S. 43-45 
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    ISSN: 1432-2048
    Keywords: Avena ; Cell elongation ; Fusicoccin ; Malate synthesis ; PEP carboxylase ; pH stat ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phytotoxin fusicoccin (FC) causes rapid synthesis of malate in coleoptile tissues, presumably via phosphoenolpyruvate (PEP) carboxylase coupled with malate dehydrogenase. The possibility that FC directly affects PEP carboxylase in Avena sativa L. and Zea mays L. coleoptiles was studied and rejected. The activity of this enzyme is unaffected by FC whether FC is added in vitro or a pretreatment to the live material. FC does not change the sensitivity of the enzyme to bicarbonate or malate. The activity of FC, instead, appears to be indirect. The pH sensitivity of PEP carboxylase is such that its activity, and thus the rate of malate synthesis, may be enhanced by an increase in cytoplasmic pH accompanying FC-induced H+ excretion. Since the enzyme is also particularily sensitive to bicarbonate levels, malate synthesis may also be enhanced by FC-induced uptake or generation of CO2.
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    URL: http://dx.doi.org/10.1007/BF00390808
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    Relationship between stomatal conductance and light intensity in leaves of Zea mays L., derived from experiments using the mesophyll as shade (1978)
    Springer
    Planta 139 (1978), S. 73-77 
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    ISSN: 1432-2048
    Keywords: Abaxial ; Adaxial ; Carbon dioxide ; Light (blue) ; Stomatal conductance ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Attached leaves of Zea mays were illuminated with monochromatic light, with either the upper or the lower epidermis facing the light source. The mesophyll absorbed between 99.5 and 99.6% of the red or blue light used. An inversion of the light direction therefore caused a 200- to 250-fold change in the quantum flux into each epidermis. This variation in quantum flux did not affect stomatal conductance. Stomatal conductance was however correlated with intercellular CO2 concentration, ci, and the relationship between stomatal conductance and ci appeared also to remain the same if changes in ci were brought about by changes in atmospheric CO2 concentration instead of light. A close inspection of the data showed that stomata of the upper (adaxial) epidermis exhibited a small increase in conductance (〈0.1 cm s-1) in response to blue light that was superimposed on the dominating response to ci.
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    Direct pollination of Zea mays ovules in vitro with Z. mays, Z. mexicana and Sorghum bicolor pollen (1978)
    Springer
    Theoretical and applied genetics 53 (1978), S. 43-46 
    Details
    ISSN: 1432-2242
    Keywords: Direct ovule pollination in vitro ; Embryo and endosperm development in vitro ; Hyperplastic nucellar growth ; In vitro pollination ; Sorghum ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Sorghum (Sorghum bicolor) pollen tubes penetrated and grew in corn (Zea mays) styles. The limited length of the sorghum pollen tubes (3–5 mm) and the absence of stigmatic hairs on the basal (5–10 mm) section of the corn styles prevented effective pollination in vivo and in vitro. Normal fertilisation occurred after in vitro pollination of exposed corn ovules with either corn or teosinte (Zea mexicana) pollen. Six per cent of corn ovules pollinated directly with sorghum pollen responded by rapid, massive growth of nucellar tissue.
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    A freeze-fracture study of tight junctions in the pars convoluta and pars recta of the renal proximal tubule (1978)
    Springer
    Cell & tissue research 186 (1978), S. 121-133 
    Details
    ISSN: 1432-0878
    Keywords: Proximal tubule ; Tight junctions ; Ultrastructure ; Electron microscopy ; Freeze fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphology of tight junctions of the renal proximal tubule was studied comparing the pars convoluta and pars recta of rat, golden hamster, rabbit, cat, dog and tupaia. Though some interspecies variations were observed, the convoluted portions of the proximal tubules revealed quite uniformly very leaky tight junctions with mainly 1–2 strands. Along the whole proximal tubule of the rabbit kidney including the pars recta only minor differences of the zonulae occludentes were found. By contrast, the tight junctions of the pars recta in other species were much more elaborate, especially in cat and tupaia, having up to 6 strands and an overall depth of more than 150 nm. The implications of these findings are discussed with special regard to the functional differences between the pars convoluta and pars recta of the proximal tubule.
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    Exocrine pancreas under experimental conditions (1978)
    Springer
    Cell & tissue research 186 (1978), S. 227-240 
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    ISSN: 1432-0878
    Keywords: Pancreas (rat) ; Pancreatic duct ligation ; Cell membrane ; Intercellular junctions ; Ultrastructure ; Freeze fracture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Exocrine pancreatic tissue was investigated during various intervals after pancreatic duct ligation. Concomitant to the increase of the intraluminal pressure, alterations are found in the arrangement of the luminal membrane surface and the zonulae occludentes of the acinar cells. The zonulae occludentes exhibit a disarrangement of their strands. The number of strands diminishes and small interruptions as well as large discontinuities of the strands are observed in most regions of the acinar cells. Furthermore, gap junctions are found very infrequently between acinar cells. The ultrastructural alterations of the zonulae occludentes suggest a gradual adaptation to the increasing unilateral pressure. However, a leakage of the paracellular permeability barrier occurs which contributes to the known shunt between the compartments of the pancreatic juice and the interstitial space following pancreatic duct obstruction. The present investigation is a further example of alterations in the paracellular permeability and intercellular communication of epithelial cells under pathological conditions.
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    Fine structure of the eyes of orb-weavers, Argiope amoena L. Koch (Aranea: Argiopidae) (1978)
    Springer
    Cell & tissue research 186 (1978), S. 435-452 
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    ISSN: 1432-0878
    Keywords: Photoreceptors ; Arthropod ; Spider (Argiope amoena) ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The anterolateral eye, the posterolateral eye and the posteromedial eye of the web-building spider, Argiope amoena have been examined by light and electron microscopy. The dioptric apparatus of all three eyes is similar in structure, and consists of a cornea, a lens and a vitreous body. The retina contains monopolar receptor cells, the cell bodies of which are present beneath the vitreous body in all three eyes. Proximal processes of the receptor cells form rhabdoms beneath the cell body layer and then extend toward the first optic glomerulus as an ocellar nerve. Two distinct patterns of retinal organization are present in the three eyes. In one type the rhabdomic layer of the retina is backed by a pigmented layer. In the other type the rhabdomic layer is backed by a tapetal reflecting layer. Rhabdomic structure and cytoplasmic inclusions of the receptor cells differ greatly between the two types. The anterolateral eye possesses a single type of retina with the rhabdoms backed by the tapetum. Both the posterolateral and the posteromedial eye are similar in structure, each possessing beneath the common dioptric apparatus retinae of both types.
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    Ultrastructure of the subfornical organ of the Japanese quail, Coturnix coturnix (1978)
    Springer
    Cell & tissue research 188 (1978), S. 19-33 
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    ISSN: 1432-0878
    Keywords: Subfornical organ ; Circumventricular organ ; Coturnix quail ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure of the subfornical organ (SFO) of the Japanese quail has been studied by light and electron microscopy. The SFO is a small semiglobular bulge in the midline on the rostrodorsal wall of the third ventricle between the anterior commissure and tela choroidea. The organ consists of three main parts, anterior stalk, the corpus and the posterior stalk. The anterior stalk is covered by ependymal cells with a few cilia, but the corpus and posterior stalk are characterized by a distinctive lack of cilia and by flat or bulging cell surfaces, which have the appearance of cobble stones. The large bulbous protrusions in the ependymal surface of the posterior stalk suggest a secretory function into the ventricle. In the subependymal layer, there are a few parvocellular neurons that contain small mitochondria, moderately developed Golgi apparatus, lysosomes, dilated cisternae of rER and a few dense-cored granules of 100–120 nm in diameter. They appear to be secretory in nature. Two types of glial cells occur in the subependymal and internal layers. One is small and spindle-shaped with a dense nucleus and elongated cytoplasmic processes; it may be microglial. The other is a small polygonal cell with rounded nucleus and clear cytoplasm containing bundles of filaments; it may be a protoplasmic astrocyte. The neuropil contains three types of axons. The first contains dense-cored granules, 80 nm in diameter, and clear vesicles, 40–60 nm in diameter and is involved in axosomatic synapses. The second type contains dense granules, 120 nm in diameter, and clear vesicles, 40–80 nm in diameter, and shows axodendritic synapses. The third contains peptidergic granules about 100–120 nm in diameter and seems to belong to the organ-specific nerve cells. These axons terminate at the perivascular space of the blood capillaries, suggesting secretion into the blood.
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    Origin of the glial processes responsible for the spontaneous postnatal phagocytosis of boutons on cat spinal motoneurons (1978)
    Springer
    Cell & tissue research 189 (1978), S. 203-217 
    Details
    ISSN: 1432-0878
    Keywords: Astrocytes ; Development ; Phagocytosis ; Neuroplasticity ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Previous studies have demonstrated that astrocyte processes are responsible for a spontaneously occurring phagocytosis of boutons on cat spinal motoneurons during the second postnatal week. In the present investigation, the astrocytes and the astrocyte processes in contact with the motoneurons were studied qualitatively and quantitatively during the early postnatal period. It could be concluded that the cells responsible for the phagocytosis of boutons are immature astrocytes. These cells were present not only during the period of phagocytosis but also prior to this period. The type of process responsible for the phagocytosis was present not only during the period of phagocytosis but also prior to and after that period although the relative contribution of such processes to the glia-covered membrane area of the motoneurons was reduced in the older animals. On the basis of these results, the possible specificity of the immature astrocyte as the element responsible for the phagocytosis of boutons during normal development is discussed.
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    URL: http://dx.doi.org/10.1007/BF00209270
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    Synaptic junctions in the sinus gland of the freshwater prawn Palaemon paucidens (1978)
    Springer
    Cell & tissue research 189 (1978), S. 435-440 
    Details
    ISSN: 1432-0878
    Keywords: Neurosecretion ; Sinus gland ; Synapses ; Palaemon ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two types of neurosecretory fibers, designated as Type 5 and Type 6 axons, in the sinus gland of the freshwater prawn, Palaemon, establish contact with other neurosecretory axons by means of synaptic junctions. This finding strongly supports the view that release of some neurohormones from the eyestalk may be regulated by neurosecretory neurons through synaptic transmission.
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    URL: http://dx.doi.org/10.1007/BF00209131
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    Structure of occluding junctions in ileal epithelial cells of suckling rats (1978)
    Springer
    Cell & tissue research 191 (1978), S. 449-462 
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    ISSN: 1432-0878
    Keywords: Ileum (Rat) ; Occluding junctions ; Freeze-fracture ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two kinds of occluding junctions are found between ileal epithelial cells of suckling rats: apical zonulae occludentes (ZO) and fasciae occludentes (FO) which are associated with the lateral plasma membranes of many epithelial cells. In unfixed preparations, glycerol treatment induces the further proliferation of extensive fasciae occludentes. Both kinds of junction have identical structural elements when visualized in freeze fracture replicas, although the arrangement of these elements differs. Zonulae occludentes consist of networks of branching and anastomosing linear ridges or rows of ∼10 nm particles with 20–30 nm spaces between the rows which form narrow belt-like structures around the apical region of adjacent cells. Fasciae occludentes, on the other hand, consist of similar linear ridges or rows of particles but the junction strands are often discontinuous, open ended and only occasionally intersect with each other. Several different fracture planes through the plasma membrane in the region of the occluding junctions have been observed and these provide further evidence that two components, one from each membrane, fused at the level of the extracellular space, form the junction sealing element. Furthermore, we present evidence which indicates a staggered rather than an in-register arrangement of these two components.
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    URL: http://dx.doi.org/10.1007/BF00219808
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    Effects of hormone-releasing stimuli on the area of the perivascular space in the neural lobe of the rat (1978)
    Springer
    Cell & tissue research 191 (1978), S. 501-506 
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    ISSN: 1432-0878
    Keywords: Neurohypophysis ; Ultrastructure ; Perivascular space ; Hormonerelease ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neural lobes from rats subjected to neurohypophysial hormone-releasing stimuli were examined electron microscopically following fixation in 4 % tannic acid in 2.5 % glutaraldehyde. This fixation allowed the delineation of the perivascular space in the neural lobe tissue. Measurement of the area of the perivascular space showed that it was significantly increased in the rats subjected to vagal stimulation and intraarterial calcium ions compared to the control rats. The rats which had been subjected to haemorrhage as a hormonereleasing stimulus did not show any significant change in the area of the perivascular space. The significance of these findings in relation to hormone release is discussed.
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    URL: http://dx.doi.org/10.1007/BF00219812
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    Lymph node macrophages and reticulum cells in the immune response (1978)
    Springer
    Cell & tissue research 192 (1978), S. 1-23 
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    ISSN: 1432-0878
    Keywords: Lymph node (rat) ; Macrophages ; Dendritic reticulum cells ; Immune response to paratyphoid vaccine ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The reactivity of rat lymph node macrophages and reticulum cells has been studied in relation to the course of the immune response. Special attention was paid to the interdigitating cells (IDC) in the paracortex and the dendritic reticulum cells (DRC) in the germinal centre. Different types of macrophage predominate in the three different phases of the immune response. In the induction phase exudate macrophages predominate. They transform their morphology depending on the micro-environment in which they settle. These cells may contain Birbeck granules. Our experiments suggest, that these granules are immunologically specific organelles, associated with the induction of a primary humoral response. In the proliferation phase transitional cells between newly arrived macrophages and IDC predominate in the paracortex and the number of IDC decreases. In the memory phase IDC repopulate this thymus dependent area, indicating that the characteristic morphology of these cells results from the immune response in the T cell environment. The DRC are specifically related to the germinal centre, the morphological transformation of this peculiar reticulum cell occurs under the influence of the germinal centre reaction. The germinal centre reaction originates by tingible body macrophages (TBM).
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    URL: http://dx.doi.org/10.1007/BF00231019
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    Morphological changes in the esophageal epithelium of the eel, Anguilla japonica, during adaptation to seawater (1978)
    Springer
    Cell & tissue research 192 (1978), S. 25-38 
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    ISSN: 1432-0878
    Keywords: Esophageal epithelium ; Eel ; Seawater adaptation ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The esophageal epithelium of the Japanese eel, Anguilla japonica, was studied by light and electron microscopy. In freshwater-adapted eels, longitudinal folds of the mucosal surface are simple in form and lined by a stratified epithelium composed of mucous cells, filament and ribosome-rich cells. Mucous cells are numerous. The filament-rich cells form the outermost and the basal layers of the stratified epithelium and are scattered in the middle zone among the mucous cells. They are firmly bound to one another by many desmosomes and prominent interdigitations of plasma membrane. The distal free surface of the filament-rich cell has a fingerprint-like pattern of microridges. A small number of columnar cells occur at the apices of the folds. They are rich in mitochondria and their distal surfaces bear short microvilli. In seawater-adapted eels, irregularly meandering folds increase the surface area of the mucosa. The stratified epithelium is extensively replaced by a simple columnar epithelium free of mucous cells. The columnar cells resemble in many respects those found in freshwater-adapted eels. They are rich in mitochondria and their distal free surface were provided with short microvilli. However, prominent lateral intercellular spaces and elaborate interdigitations of cytoplasmic processes in the distal zone distinguish the former from the latter. Results are considered in connection with the changes in ion and water permeability of the epithelium after seawater adaptation.
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    URL: http://dx.doi.org/10.1007/BF00231020
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    Ultrastructure of capillaries in the conduction system of the heart in various mammals (1978)
    Springer
    Cell & tissue research 192 (1978), S. 77-87 
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    ISSN: 1432-0878
    Keywords: AV-node ; AV-bundle ; Fenestrated capillary endothelium ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The capillaries in the atrioventricular node and atrioventricular bundle of the heart (mammals) were investigated by thin sections and freezeetch replicas. Fenestrated endothelial cells were found to occur in all mammals examined in this study. These fenestrations (500±50 Å diameter) are bridged by a diaphragm and occur in relatively small sieve areas. In contrast to the AV-node and AV-bundle, the non-specialized myocardium is supplied by continuous capillaries. The presence of the fenestrated capillary in the conduction system of the heart may serve to increase both permeability and passive transport capacity.
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    URL: http://dx.doi.org/10.1007/BF00231024
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    A stereological ultrastructural study of peritoneal macrophages from germ-free and conventionally-reared mice (1978)
    Springer
    Cell & tissue research 192 (1978), S. 157-166 
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    ISSN: 1432-0878
    Keywords: Germ-free mice ; Macrophages ; Peritoneum ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The reported work is the first direct ultrastructural comparison of resident peritoneal macrophages from germ-free and conventional animals. Three groups of mice were studied: germ-free (GF), conventionally-reared under isolation conditions (IC), and conventionally-reared in an open environment (OC). The macrophages from the three groups of animals are closely similar morphologically. Particularly noteworthy are the electron-dense, lysosome-like granules which are numerous in the macrophages of germfree mice and which provide a structural foundation for the presumed microbicidal capability of the phagocytes. Morphometric estimates showed that the “average macrophage” from GF mice is smaller and possesses a smaller, rounder nucleus, a smaller volume fraction of mitochondria and more lysosome-like granules per unit of cytoplasmic volume than the “average macrophage” from conventional mice. Moreover, granules and mitochondria are smaller, on average, in the GF phagocytes than in macrophages from conventional mice. The results suggest that peritoneal macrophages from the germ-free mouse represent, more truly than those from the conventional mouse, the nature of the fully differentiated but as yet unstimulated mononuclear phagocyte.
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    URL: http://dx.doi.org/10.1007/BF00231030
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    Ultrastructural analysis of the action of reserpine on the brain neuroendocrine system of the wax moth, Galleria mellonella L., Lepidoptera (1978)
    Springer
    Cell & tissue research 192 (1978), S. 143-155 
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    ISSN: 1432-0878
    Keywords: Neuroendocrine system ; Galleria ; Ultrastructure ; Reserpine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This study concerns the influence of reserpine on the fine structure of peptidergic neurosecretory cells in the pars intercerebralis of Galleria mellonella, and of neurons containing smaller dense-cored vesicles (presumed to be aminergic) localized in the same area of the brain. The drug, administered in doses of 125 μm and 250 μg per g of insect body weight, reduces both the amount and the electron opacity of the dense-cored vesicles with a diameter of 60–80 nm in the neuronal perikarya as well as their terminals. Simultaneously, this treatment evokes an abnormal accumulation of secretory granules within the perikarya of peptidergic neurosecretory cells belonging to three types. This accumulation of secretory material is followed by some changes in the fine structure of these cells. One (fourth) type of neurosecretory cells seems to be insensitive to reserpine action. Participation of the aminergic system in the regulation of the secretory activity of some populations of peptidergic neurosecretory neurons of the insect brain is postulated.
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    URL: http://dx.doi.org/10.1007/BF00231029
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    Structure of the adenohypophysis in parturient female and neonate harp seals, Pagophilus groenlandicus (1978)
    Springer
    Cell & tissue research 192 (1978), S. 341-357 
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    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Cell types ; Neonate ; Parturient ; Harp seal, Phagophilus groenlandicus ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pars distalis of parturient harp seals (Pagophilus groenlandicus) is divisible into three distinct zones based on the major cellular components of the different regions. A clear zonation is lacking in neonate seals, the medial “basophilic wedge” and the anterior gonadotrophic were small and difficult to identify. Five cell types were identified based on cytological characteristics: somatotrophs, mammotrophs, thyrotrophs, gonadotrophs and stellate cells; corticotrophs could not be identified, with any certainty, in any of the preparations, nor could the gonadotrophs be classified into LH, FSH, and ICSH cells. The pars intermedia enlarged during the early post-partum period and was large in the parturient females.
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    URL: http://dx.doi.org/10.1007/BF00220751
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    Studies on the ultrastructure and permeability of the hemotrichorial placenta (1978)
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    Cell & tissue research 192 (1978), S. 391-407 
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    ISSN: 1432-0878
    Keywords: Placenta (rat) ; Permeability ; Tracer ; Intercellular junctions ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of lanthanum chloride and horseradish peroxidase within the full-term chorioallantoic placenta of the rat was investigated 1 to 20 min after administration of these tracers into the maternal blood circulation. Both tracers rapidly penetrate trophoblastic layer I and diffuse into the interspace between layers I and II. They are localized in extensive infoldings and caveolae of the outer surface of layer II. The syncytial character of layer II is confirmed at this developmental stage of the placenta. There is no vesicular uptake or penetration beyond layer II until 20 min after tracer administration. Our results indicate that trophoblastic layer II is the main barrier in the chorioallantoic rat placenta preventing the permeation of macromolecules from maternal to fetal compartments. With freeze-fracturing, particulate structures of variable arrangement and size are found between adjacent cells of layer I. With goniometric analysis small gaps between the appositions of the membrane are observed. These structures are interpreted as tight and/or gap junctions during stages of assembly or disassembly.
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    URL: http://dx.doi.org/10.1007/BF00212321
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    Studies on the ultrastructure and permeability of the hemotrichorial placenta (1978)
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    Cell & tissue research 192 (1978), S. 409-422 
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    ISSN: 1432-0878
    Keywords: Placenta (rat) ; Capillary ; Permeability ; Tracer ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of horseradish peroxidase and lanthanum chloride within the full term chorioallantoic placenta of the rat was examined after administration of these tracers into the umbilical artery. Both tracers rapidly traverse the capillary endothelium. Transendothelial channels, fenestrations and micropinocytotic vesicles provide the main pathways. Intercellular clefts which are either patent or interrupted by leaky intercellular junctions, also contribute to a rapid passage of low and high molecular weight substances. Deep channel-like invaginations, effecting an increase of the exchange area of layer III, are freely accessible to the tracers from the interspace between the capillary endothelium and trophoblastic layer III. The invaginations, however, are not in continuity with the interspace between layers II and III, verifying the syncytial character of layer III. Neither an uptake of the tracers nor a passage across layer III is observed. The main permeability barrier to feto-maternal transfer within the chorioallantoic placenta is localized in the syncytiotrophoblastic layer III. This layer controls the passage of low molecular weight substances and restricts the penetration of high molecular weight substances.
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    URL: http://dx.doi.org/10.1007/BF00212322
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    Lipid detection by malachite green-aldehyde in the dental basement membrane in the rat incisor (1988)
    Springer
    Cell & tissue research 253 (1988), S. 685-687 
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    ISSN: 1432-0878
    Keywords: Basement membrane ; Lipids ; Ultrastructure ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Developing rat incisors were treated with malachite green-aldehyde fixative solution (MGA), which retains and stains lipids. We observed positive staining occurring as dots in the basement membrane. Most of these dots (2–3.5 nm in diameter) were grouped in the lamina densa but some were also present in the lamina lucida and the lamina fibroreticularis. These data provide evidence for the existence of lipids in the dental basement membrane and suggest that they are distributed together with the various groups of proteins so far detected.
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    URL: http://dx.doi.org/10.1007/BF00219762
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    Catecholaminergic nerves in the embryonic chick ovary: co-localization with β2-adrenoceptor-bearing steroidogenic cells (1988)
    Springer
    Cell & tissue research 254 (1988), S. 1-9 
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    ISSN: 1432-0878
    Keywords: Adrenergic nerves ; Steroidogenic cells ; Embryonic ovary ; β 2Adrenoceptors ; Cytochemistry ; Ultrastructure ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present study investigates the innervation of the embryonic chick ovary with regard to (i) development and compartmentalization of catecholaminergic nerves, and (ii) presence of adrenoceptors on steroidogenic target cells of catecholaminergic nerve terminals. Catecholaminergic nerve fibers visualized by glyoxylic acid-induced histofluorescence first appeared at embryonic day (E) 13. From E15 through E21 the density of fluorescent aminergic nerves increased markedly in parallel with the concentration of catecholamines and numbers of nerve bundles and single axons seen at the electron-microscopic level. Catecholaminergic nerves were confined to the ovarian medulla and closely associated with interstitial cells. Nerve terminals approached interstitial cells up to a distance of 20 nm and, in their majority, exhibited uptake of the false adrenergic transmitter 5-hydroxydopamine. Although adrenaline amounted to 14% of the total catecholamine content at E21, adrenaline immunoreactivity was only detected in adrenal chromaffin cells, but not in nerve fibers or cell bodies within the ovary. Interstitial cells structurally matured between E15 and E21 as documented by an increase of smooth endoplasmic reticulum and tubular mitochondria. Monoclonal antibodies mAB 120 and BRK 2 raised against avian β 1 and mammalian β 2-adrenergic receptors revealed the presence of β 2-adrenoceptor-like immunoreactivity on the surface of interstitial cells, but not on any other cell type. The results are consistent with the notion of a dense adrenergic innervation of the embryonic chick ovarian medulla and its steroidogenic interstitial cells, and suggest the chick ovary as an excellent model for elucidating the functional role of a neural input to steroidogenic cells during development.
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    URL: http://dx.doi.org/10.1007/BF00220010
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    The pattern of organization of intermediate filaments and their asymmetrical association with dense bodies in smooth muscle of an ascidian Halocynthia roretzi (1988)
    Springer
    Cell & tissue research 252 (1988), S. 23-32 
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    ISSN: 1432-0878
    Keywords: Smooth muscle ; Intermediate filaments ; Dual network ; Ultrastructure ; Ascidian ; Halocynthia roretzi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An extensive network of intermediate filaments that interconnected cytoplasmic dense bodies and connected the dense bodies to the cell surface was revealed in double-fixed, tannic acid-stained preparations of ascidian smooth muscle. The filament network ran through spaces in the continuous network of myofibrils, connecting them longitudinally, obliquely and transversely to form an intimately associated, dual network. In their transverse passage, the intermediate filaments ran across myofibrils along I-zones exclusively, interconnecting successive dense bodies. The pattern of attachment of intermediate filaments to dense bodies was predominantly “one-sided.” The filaments, which themselves were not incorporated into the contractile apparatus, remained folded or unfolded between myofibrils and between sarcomere-like structures in synchrony with the contraction-relaxation cycles. These results suggest that the intermediate filaments mechanically maintain the organization and arrangement of myofibrils via an intimate association with the myofibrils in the regions of the dense bodies, in such a way that the filaments do not impede muscle function. Based on these observations, a new model for the network of intermediate filaments in smooth muscle cells is proposed.
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    URL: http://dx.doi.org/10.1007/BF00213822
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    Ultrastructure of the tentacles of the apodous holothurian Leptosynapta spp (Holothurioidea: Echinodermata) with special reference to the epidermis and surface coats (1988)
    Springer
    Cell & tissue research 251 (1988), S. 387-397 
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    ISSN: 1432-0878
    Keywords: Tentacles ; Ultrastructure ; Adhesion ; Leptosynapta spp (Holotheorie) ; Echinodermata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The tentacles of the apodous holothurian Genus Leptosynapta have been studied by use of transmission and scanning electron microscopy. The gross anatomy, water vascular system, fibre systems and ectoneural nerve ring are described. A fuzzy coat of attenuated filaments covers the surface of the tentacle, broken only by secretory ducts. A cuticle underlies the fuzzy coat. Bacteria are common in the subcuticular space. Fixation without osmium gives poor preservation of the surface coats. The epidermis consists of a single layer of columnar cells consisting of Type-1, Type-2, support, goblet and uniciliated cells. Type-1 cells secrete electron-dense material and appear to be homologous to adhesive cells of the tentacles of other holothurians. The support cells contain large, granular vesicles not found in other holothurians. Goblet cells contain flocculent mucus and have an apical cilium. Goblet cells are not found in other holothurian tentacles and may function to lubricate and wrap adhering particles to aid their ingestion. The uniciliated cells are rare, poorly developed and the cilium does not extend past the cuticle. The ultrastructure of the tentacles is discussed in relation to those of other holothurians.
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    The ultrastructure of the lung of two newborn marsupial species, the northern native cat, Dasyurus hallucatus, and the brushtail possum, Trichosurus vulpecula (1988)
    Springer
    Cell & tissue research 252 (1988), S. 683-685 
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    ISSN: 1432-0878
    Keywords: Lung ; Ultrastructure ; Marsupial ; Newborn ; Surfactant ; Dasyurus hallucatus, Trichosurus vulpecula
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The lungs of newborn northern native cats, Dasyurus hallucatus and newborn brushtail possums, Trichosurus vulpecula were examined by both light and electron microscopy. The native cat has a birth weight of 18 mg after a gestation of about 21 days, whereas the brushtail possum weights 200 mg at birth and has a gestation period of 17.5 days. The lungs of the native cat are two large respiratory sacs, with a respiratory lining of squamous cells and surfactant-secreting cells. The capillaries are located within the connective tissue just below this respiratory epithelium. The visceral covering of the lung is formed by squamous cells. The lungs of the possum are composed of numerous large respiratory sacs which are separated by connective tissue septa in which the capillaries are located. The sacs, as in other species, are lined with squamous cells and surfactant secreting cells. It is proposed that the structure of the lung of the newborn marsupial is related more to the size of the newborn rather than to the length of the gestation period.
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    URL: http://dx.doi.org/10.1007/BF00216657
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    Vascular response in a non-uterine site to implantation-stage embryos in the rat and guinea-pig: in vivo and ultrastructural studies (1988)
    Springer
    Cell & tissue research 254 (1988), S. 217-224 
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    ISSN: 1432-0878
    Keywords: Implantation ; Embryo ; Ultrastructure ; Vasculature ; Rat (Sprague-Dawley) ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Preimplantation-stage embryos were transferred to the anterior eye chamber of recipient rats and guinea-pigs. After implantation had occurred the influence of the embryo on the iris vasculature was examined ultrastructurally. In both species, the earliest effect of embryonic implantation was an increased stromal oedema. Under increasing embryonic influence the vascular endothelial cells showed an increased number of projections into the vascular lumen, while in the rat, endothelial projections were also found pushing back into the basement membrane. In the rat, the endothelium became very irregular in thickness prior to complete disintegration and loss during more advanced stages of implantation. Rat embryonic trophoblast was found invading iris vasculature, particularly in areas where the iridial endothelium was partially or completely missing. Other cells in the iris, including the stroma, appeared to be less affected. In the guinea-pig, however, trophoblast cells appeared to be capable of invading the vasculature by displacing endothelial cells that still appeared morphologically normal.
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    Morphological, histochemical, and ultrastructural characterization of the accessory cells of neuromasts in the salamander Pleurodeles waltlii (1988)
    Springer
    Cell & tissue research 254 (1988), S. 233-240 
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    ISSN: 1432-0878
    Keywords: Lateral-line sense organs ; Mechanoreceptors ; Supporting cells ; Ultrastructure ; Pleurodeles waltlii (Urodela)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural and histochemical features of the accessory cells of the neuromast of the salamander P. waltlii have been examined. Three types of accessory cells, supporting, mantle, and basal, were found, but only the first 2 are considered in this article. Supporting cells characterized by a highly dilated endoplasmic reticulum occur among and surrounding sensory cells. Mantle cells, morphologically different from the supporting cells, surround the remainder of the neuromast. Both types of accessory cells exhibit histochemically different secretory materials. Our morphological results suggest that both accessory cells contribute to the formation of cupular material.
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    URL: http://dx.doi.org/10.1007/BF00220039
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    Influence of a short light pulse at night on the ultrastructure of the rat pinealocyte: a quantitative study (1988)
    Springer
    Cell & tissue research 254 (1988), S. 247-249 
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    ISSN: 1432-0878
    Keywords: Pinealocyte ; Light exposure ; Ultrastructure ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Although it is generally known that light strongly influences N-acetyltransferase activity and melatonin production in the pineal gland, little information is available concerning morphological changes following light exposure. As exposure of rats to a short light pulse at night rapidly depresses melatonin synthesis, we decided to determine whether this experimental condition produces rapid changes in the pinealocyte organelles. A 30-min light pulse at night (six hours after lights out) provoked rapid changes in the relative volumes of some pinealocyte organelles. The volume fractions of mitochondria, Golgi apparatus and lipid droplets, and the numbers of dense-core vesicles and “synaptic” ribbons decreased, whereas the volume fraction of lysosomes increased. There were no differences in the volumes of granular endoplasmic reticulum and vacuoles containing flocculent material in those animals exposed to light compared with control animals. These results indicate that a short light pulse at night causes ultrastructural changes that can be interpreted as morphological features of diminished activity of pinealocytes.
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    URL: http://dx.doi.org/10.1007/BF00220041
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    Neurosecretory centers from the eyestalk of Siriella armata M. Edw. (Crustacea: Mysidacea): ultrastructural variations during normal and experimentally inhibited molt cycle (1988)
    Springer
    Cell & tissue research 254 (1988), S. 381-391 
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    ISSN: 1432-0878
    Keywords: X-organ ; Sinus gland ; Ultrastructure ; Cyclic activity ; Siriella armata (Crustacea)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the medulla interna-medulla externa X-organ (MI-ME Xo)-sinus gland (SG) complex in the eyestalk of Siriella armata is described during the normal and the experimentally inhibited molt cycle. In the normal SG, four types of neurosecretory axon terminals, each containing distinguishable neurosecretory granules, can be described. Thus, type-2 granules are synthesized by G1 neurons forming the MI-ME Xo. The cell bodies and axonal endings of these cells in the sinus gland have been examined at the following molt stages: intermolt (stage C4), premolt (D0 and D2), and postmolt (A1, A2 and B). Changes in ultrastructure of the G1 cells have been monitored and correlated to inhibitions of the molt-and reproductive cycle produced by electrocauterization of the MI-ME Xo. The results obtained suggest that the neurosecretion from the G1 cells exerts a positive influence on molt and brood preparation. The occurrence of a distal group of G1 cells whose axons terminate at a different site from the SG suggests that the neural factors of the MI-ME Xo are diverse and control different physiological activities.
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    URL: http://dx.doi.org/10.1007/BF00225810
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    Control of the pars intermedia of the lizard, Anolis carolinensis (1978)
    Springer
    Cell & tissue research 186 (1978), S. 241-258 
    Details
    ISSN: 1432-0878
    Keywords: Neural lobe ; Anolis carolinensis ; Ultrastructure ; Intermediate lobe control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the neural lobe of the lizard, Anolis carolinensis, was studied after fixation in a threefold aldehyde solution. The neural lobe appeared as narrow vertical diverticula separated from one another and from the pars intermedia by a continuous vascular septum. No nerves passed through this septum. The ependymal, fibrous and external layers were readily recognized. Peptidergic fibres were the main component of the fibrous layer. The peptidergic endings were in intimate contact with the ependymal cells, suggesting that the ependyma mediates the release of neural lobe peptides. The external layer contained ependymal end-feet and numerous aminergic terminals, ending directly on the perivascular basal lamina and/or on the ependymal end-feet. The functional aspects are discussed in terms of intermediate lobe control. The findings suggest that aminergic substances take part in the control of the intermedia, but do not exclude the involvement of peptide hormones.
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    URL: http://dx.doi.org/10.1007/BF00225534
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    Ultrastructure and lipid content of the liver of the zebrafish, Brachydanio rerio, related to vitellogenin synthesis (1978)
    Springer
    Cell & tissue research 186 (1978), S. 297-308 
    Details
    ISSN: 1432-0878
    Keywords: Liver ; Teleost ; Ultrastructure ; Lipid ; Vitellogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The female zebrafish is capable of producing mature eggs on the fifth day of each reproductive cycle. During this five-day period the ultrastructure of hepatocytes undergoes several changes. The number of nuclear pores increases rapidly during spawning, followed by a proliferation of RER within 24 h. Two days after spawning, glycogen has disappeared and the liver contains large amounts of lipids. The lipid droplets are closely surrounded by elongated mitochondria. Golgi complexes are abundant, secreting dense bodies. Four days after spawning the hepatocytes tend to regain their pre-spawning appearance. It is suggested that the changes in the hepatocytes, which coincide with special phases of ovarian activity, are related to vitellogenin synthesis. Steroids, especially estradiol-17β, may trigger this process in the liver.
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    URL: http://dx.doi.org/10.1007/BF00225539
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    An ultrastructural study of the larval integument of the midge, Chironomus riparius meigen (Diptera: Chironomidae) (1978)
    Springer
    Cell & tissue research 186 (1978), S. 327-335 
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    ISSN: 1432-0878
    Keywords: Cuticle ; Epidermis ; Chironomus ; Respiration ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The larval integument of the midge, Chironomus riparius Mg., is unusually thin although it conforms with the normal insect pattern. The cuticle of the post-cephalic segments is about 3 μm thick and overlies an epidermis which has an irregular basal plasma membrane resulting in spaces occurring between it and the basement membrane. The ventral tubuli have a similar epidermis but the cuticle is somewhat thinner. The anal papillae have the thinnest cuticular covering with a uniquely folded epicuticle of variable thickness, and their epidermis has the characteristics of a transporting epithelium. No evidence of pore canals could be found in the cuticle of any part except the head capsule which has a remarkably smooth epicuticle and a distinct layer which may represent the exocuticle. There are no spaces between the basement membrane and basal plasma membrane of the epidermis in the head. Ultrastructural evidence would suggest that gaseous exchange can occur across most of the post-cephalic integument.
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    URL: http://dx.doi.org/10.1007/BF00225541
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    Effects of systemic administration of 6-hydroxydopamine on the circumventricular organs in nonhuman primates (1978)
    Springer
    Cell & tissue research 187 (1978), S. 115-127 
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    ISSN: 1432-0878
    Keywords: Area postrema ; 6-Hydroxydopamine ; Degenerative changes ; Ultrastructure ; Cynomolgus and squirrel monkeys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 6-Hydroxydopamine (6-OH-DA) has been shown to produce degenerative changes in noradrenergic nerve terminals and preterminals in the CNS following intracisternal, intraventricular or direct injection into the brain parenchyma. Systemic injection of 6-OH-DA is known to result in degenerative changes in noradrenergic terminals in the peripheral nervous system. However, only a few studies have been carried out on the effects of systemic injections of 6 OH-DA on noradrenergic terminals in the CNS. In the present study cynomolgus and squirrel monkeys were injected intravenously on two successive days with total doses of 350mg/kg and 150 mg/kg of 6-OH-DA, respectively, and sacrificed at 2 and 24 h following the second injection. Degenerative changes in the area postrema (AP) neurons in all injected animals were characterized by a generalized increase in electron density of cytoplasmic elements in axonal terminals and preterminals. Multilamellar bodies, clusters of clear and dense core vesicles, increased numbers of secondary lysosomes, and an increase in the number of glycogen granules were observed in these structures. In astrocytes the amount of glycogen increased markedly in injected animals, but no other glial alterations were observed. The number of mast cells in the AP was greater in injected than in noninjected animals, both in the perivascular spaces (PVS) and in parenchymal locations. Cell processes in the PVS were occasionally observed to contain electron dense bodies, and degenerative changes were seen in supraependymal processes in some injected animals.
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    URL: http://dx.doi.org/10.1007/BF00220623
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    Osteodentine and vascular osteodentine of Anarhichas lupus (L.) (1978)
    Springer
    Cell & tissue research 187 (1978), S. 135-146 
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    ISSN: 1432-0878
    Keywords: Osteodentine ; Anarhichas lupus ; Ultrastructure ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Le tissu dentinaire d'Anarhichas lupus s'est révélé être une ostéodentine vasculaire. Les études en MET, MEB et diffraction X montrent l'hétérogénéité de ce tissu. L'aspect désordonné des fibres de collagène, incomplètement minéralisées (leur striation est encore bien visible), explique la complexité de la répartition des cristaux puisqu' elles en déterminent l'ordonnance. La minéralisation imparfaite du tissu, dont témoignait déjà la striation visible du collagène, est confirmée par l'analyse des poudres en diffraction X (la cristallinité de l'ostéodentine vasculaire est nettement inférieure à celle de la couche de tissu dentaire périphérique) et par l'examen en MET de haute résolution, aucun réseau cristallin n'ayant pu être mis en évidence. L'ostéodentine, l'os basal et l'os profond ont en commun une phase minérale, avec une organisation plus ou moins bonne, différente du système des apatites.
    Notes: Summary TEM, SEM and X-ray diffraction analysis demonstrate the heterogeneity of the dentinal tissue of Anarhichas lupus, a vascular osteodentine. The disordered aspect of collagen fibres, incompletely mineralized (the periodical striation being still visible), explains the scattered distribution of crystallites since they are responsible for their arrangement. The low degree of mineralization revealed by the visible collagen striation is confirmed by X-ray diffraction analysis (the crystallinity of vascular osteodentine being much lower than that of the peripheral dental tissue) as well as by high resolution TEM, since no lattice planes could be observed. Osteodentine, supporting bone and proper bone have in common a mineral phase, more or less organized, different from the apatite system.
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    URL: http://dx.doi.org/10.1007/BF00220625
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    The ultrastructure and renewal of the intestinal epithelium of the juvenile grasscarp, Ctenopharyngodon idella (Val.) (1978)
    Springer
    Cell & tissue research 187 (1978), S. 181-200 
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    ISSN: 1432-0878
    Keywords: Intestine ; Teleost ; Epithelium ; Renewal ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The intestinal absorptive epithelium of starved and fed fish has been studied electron microscopically. After feeding, cells of the proximal segment of the intestine show morphological characteristics of lipid absorption. Absorptive cells in the middle segment contain many pinocytotic vesicles in both fasted and fed specimens. Absorption of protein macromolecules is supposed to be one of the main functions of this part of the gut. In the most caudal part of the intestine, absorptive cells carry relatively few and short microvilli. The proximal and distal segments show structural indications of a function in osmoregulation. The renewal of the epithelium has been studied with light microscopic autoradiography, using tritiated thymidine. The intestinal mucosal fold epithelium represents a cell renewal system. The cells proliferate at the base of the fold and migrate towards the apex in 10–15 days at 20° C. The functional absorptive cells proved to be generally present in the intestinal epithelium, including the proliferative area. Undifferentiated cells have not been identified. The results will be compared with data on absorption of lipid and protein macromolecules in teleostean and mammalian intestines and with descriptions of the cell renewal system in the mammalian intestine.
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    URL: http://dx.doi.org/10.1007/BF00224364
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    The ultrastructure of the non-neurosecretory components in the brain of the midge, Chironomus riparius Mg. (Diptera: Nematocera) (1978)
    Springer
    Cell & tissue research 187 (1978), S. 355-366 
    Details
    ISSN: 1432-0878
    Keywords: Neuron ; Glial ; (Insect, Chironomus riparius) ; Extracellular space ; Perineurium ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the neural sheath, glial cells and neurons in the brain of the neoimaginal male Chironomus riparius is described. The neural sheath comprises a neural lamella and underlying perineurium. The neural lamella consists of an amorphous matrix in which fine fibrils occur. The perineurium is composed of two cell types forming a continuous layer around the brain. The subjacent cortical layer, composed of the cell bodies of neurons and glial cells, varies considerably in thickness and surrounds the centrally located neuropiles. Three types of glial cells are distinguished on the basis of their positions and appearances. Five types of neurons are described which differ in size and relative frequency of organelles. Four types of axons, including those of neurosecretory cells, are distinguished by their size and content.
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    URL: http://dx.doi.org/10.1007/BF00224376
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    The posterior pituitary of the garden dormouse (Eliomys quercinus L.) (1978)
    Springer
    Cell & tissue research 188 (1978), S. 189-204 
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    ISSN: 1432-0878
    Keywords: Neural lobe of hypophysis ; Hibernating mammals ; Ultrastructure ; Neurosecretory granules ; Whorls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé L'ultrastructure de la posthypophyse du Lérot a été examinée à différents stades du cycle annuel de ce rongeur hibernant. Il n'a pas été observé de différences évidentes entre les stades étudiés, et sont donc présentées ici les caractéristiques générales retrouvées chez tous les animaux. Les axones neurosécréteurs et leurs terminaisons peuvent être divisés en deux catégories suivant l'aspect des grains de neurosécrétat et des microvésicules présents. Le premier type contient des grains arrondis, à contenu d'apparence homogène, avec des microvésicules rondes. Dans les autres axones, les grains sont de forme variable, souvent allongés, et leur contenu présente deux sortes d'organisations cristallines; les microvésicules y sont en majorité aplaties. Considérant comme improbable que cette dualité résulte seulement d'un artefact, trois hypothèses sont envisagées. La dualité d'aspect des grains peut être liée à leur contenu en hormone (ocytocine ou vasopressine); ou bien l'aspect des grains peut correspondre à leur degré de maturation. Il est possible aussi que ces explications soient toutes deux valables. Par ailleurs, les pituicytes du Lérot contiennent fréquemment un réticulum endoplasmique organisé en lamelles concentriques (whorls). La signification de ces formations reste pour l'instant obscure.
    Notes: Summary Ultrastructural examination of the posterior pituitary of the garden dormouse (Eliomys quercinus L.) was carried out at different times in the annual cycle of this hibernating rodent. Obvious differences between experimental groups have not been observed, and the results presented here must be considered as general features of the garden dormouse posterior pituitary. Neurosecretory axons and endings can be divided into two types, according to different aspects of neurosecretory granules (NSG) and microvesicles (MV). One type contains spherical NSG with homogeneous cores and round MV. In the other type, NSG have various, often elongated, shapes. Their content shows two types of crystalline structures and most of the MV have flattened aspects. As it is very unlikely that this duality in NSG is a result of an artefact of fixation, three hypotheses are presented as explanation. The duality of NSG might be related either to their hormonal content (oxytocin or vasopressin) or to their degree of maturation. Moreover, both explanations may be valid. In the species studied, pituicytes often contain concentric lamellar structures of the endoplasmic reticulum (whorls), the significance of which remains obscure.
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    URL: http://dx.doi.org/10.1007/BF00222630
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    Ovarian follicles of normal NMRI mice and homozygous “Nude” mice (1978)
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    Cell & tissue research 188 (1978), S. 409-426 
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    ISSN: 1432-0878
    Keywords: Ovary ; “Nude” mouse ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ovarian follicles of juvenile (15-day and 21-day old), pubescent (28-day old) and sexually mature (45-day old) “Nude” mice have been compared to those from normal NMRI mice of the same age and breeding groups. At the electron microscopical level, some differences were observed in both follicular cells and oocytes. In the follicular cells, the following alterations could be seen in the “Nude” ovaries: (1) the differentiation between clear and dark cells, normally not occurring before the age of 21 days, was already present in the 15-day old “Nude” mice and (2) the follicular intercellular spaces were frequently dilated, possibly because of a contraction of the cells, even in the small growing follicles of the bilaminar type in the athymic animals. The “Nude” oocytes could be characterized by (1) a precocious appearance and an early disappearance of the nuage material, (2) a nearly complete absence of micropapillae on the oolemma, (3) a dense and disseminated aspect of their Golgi complexes, (4) the presence of a large amount of multivesicular bodies and (5) of tiny (about 30 nm) dense membrane-bounded particles in their ooplasm. These differences are discussed in relation to the possible interference of congenital athymia with the development of the hypothalamo-pituitary-gonadal axis. However, the influence of the reduced immunological responsiveness of the “Nude” mice on their ovarian development cannot be excluded for animals raised in a normal — and consequently infected — environment.
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    URL: http://dx.doi.org/10.1007/BF00219781
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    Histological and cytological studies on the fat body of the cockroach Nauphoeta cinerea during the first reproductive cycle (1978)
    Springer
    Cell & tissue research 188 (1978), S. 481-490 
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    ISSN: 1432-0878
    Keywords: Fat body ; Cockroach ; Reproductive cycle ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The central fat body of the ovoviviparous cockroach Nauphoeta cinerea was studied during the first reproductive cycle of the female by means of light microscopy, autoradiography and electron microscopy. Comparative studies in larval stages were also undertaken. The fat body of Nauphoeta contains a large amount of lipid droplets and the remaining cytoplasm is very scarce. The cytological cyclicity of the fat body is consistent with the known biochemical rhythms of vitellogenin production. The proteosynthetic apparatus appears about 3 days after imaginal ecdysis, along with vitellogenin. The ribosomal endoplasmic reticulum (RER) shows a tremendous increase by the 7th day of the first cycle. The most active period of vitellogenin production lasts from day 7 to day 12. The proteosynthetic apparatus then returns to an inactive stage and disappears. This inactive condition lasts to the end of the gestation period. The autoradiographic results are consistent with the cytological features.
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    URL: http://dx.doi.org/10.1007/BF00219785
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    The ultrastructure and function of follicle cells in Foucartia squamulata (Herbst) (Curculionidae) (1978)
    Springer
    Cell & tissue research 189 (1978), S. 347-353 
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    ISSN: 1432-0878
    Keywords: Vitelline membrane ; Chorion ; Ultrastructure ; Curculionidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The follicle cells of Foucartia squamulata are involved in the formation of both vitelline membrane and chorion. Precursors for these egg coverings are synthesized by the rough endoplasmic reticulum and condensed within dictyosomes. The vitelline membrane and the chorion appear on the oocyte surface simultaneously, which is an unusual phenomenon for insects. The follicular epithelium has not been found to contribute to vitellogenesis in the species under study.
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    URL: http://dx.doi.org/10.1007/BF00209282
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    Oogenesis in Acerentomon gallicum Jonescu (Protura) (1978)
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    Cell & tissue research 189 (1978), S. 365-374 
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    ISSN: 1432-0878
    Keywords: Previtellogenesis ; Oocyte ; Ultrastructure ; Acerentomon gallicum ; Protura
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary At the onset of previtellogenesis, the oocytes of Acerentomon gallicum begin to grow and increase their content of organelles. The nuage material in the oocytes at first increases in amount, then declines gradually to disappear completely from oocytes that have attained 50 μm in diameter. During the growth period, new dictyosomes, mitochondria and ribosomes appear. Numerous vesicles become detached from the cell membrane and subsequently fuse into cisternae, thus forming extensive complexes of the rough endoplasmic reticulum. In oocytes with diameters between 50 and 100 μm the Golgi complexes show a considerable increase in activity, and many lamellar bodies arise from mitochondria that have undergone specific transformation.
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    Tormogen cell and receptor-lymph space in insect olfactory sensilla (1978)
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    Cell & tissue research 189 (1978), S. 549-554 
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    ISSN: 1432-0878
    Keywords: Tormogen cell ; Receptor-lymph space ; Chemoreceptor ; Ultrastructure ; Histochemistry ; Calliphora (Insects)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary (1) The basiconic sensilla on the antennae of Calliphora resemble other insect epidermal sensilla; one or several bipolar sense cells are surrounded by three non-neural cells. (2) The apical cell membrane of the tormogen cell(one of the three accessory cells) forms microvilli coated internally with particles. (3) In the (extracellular) outer receptor-lymph space hyaluronic acid can be demonstrated histochemically. (4) Demonstration of non-specific alkaline phosphatase, Mg2+-activated ATPase, and the presence of mitochondria in the apical part of the tormogen cell suggest active transport processes through these cells into the outer receptor-lymph space.
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    URL: http://dx.doi.org/10.1007/BF00209140
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    Kinetics of functional and morphological changes during decoupling and recoupling induced by glycerol in isolated muscle fibres of the crayfish (1978)
    Springer
    Cell & tissue research 192 (1978), S. 167-185 
    Details
    ISSN: 1432-0878
    Keywords: T-system tubules ; Glycerol procedure ; Structure-activity relationship ; Ultrastructure ; Astacus fluviatilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of ultrastructural changes in the T-system of isolated muscle fibres of the crayfish by the glycerol procedure is described in correlation with the dissociation of excitation-contraction (E-C) coupling as well as with recoupling of the E-C link. The sequence of events in the process of disconnection of the tubules is as follows: dilation of the T-system tubules, disconnection of the constricted tubular segments from the surface membrane and from the T-system vesicle, disappearance of the lumen and its disintegration. The decoupled state is characterised by the presence of round vesicles uniformly distributed in the entire volume of the fibre. The volume of vesicles accounts well for the residual postglycerol volume increase (15%) of the muscle fibres. Functional and structural recovery can be induced by reapplication of glycerol to fibres decoupled and vesiculated with concentrations of glycerol≦300mmol · l-1 in crayfish saline. The restitution starts with the organisation of the material of the disintegrated connecting segment of the T-system tubule into small vesicles which coalesce to form the tubule from the vesicular site. At the same time the surface membrane is invaginated toward the vesicle, thus forming the tubule from the surface membrane site. Recovery starts already in the first minute after application of glycerol and is completed within approximately 15min.
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    Study of neuropeptide Y-containing nerve fibers in the human penis (1988)
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    Cell & tissue research 254 (1988), S. 69-74 
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    ISSN: 1432-0878
    Keywords: Neuropeptide Y (NPY) ; Penis erection ; Perivascular nerve fibers immunocytochemistry ; Ultrastructure ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neuropeptide Y 1–36 (IR-NPY) immunoreactive nerve-fiber processes have been observed in tunicae of veins and arteries and in smooth muscles of the human penis taken at autopsy or during surgery by use of light-and electron-microscopic immunohistochemical techniques. Numerous IR-NPY nerve fibers were mostly concentrated in the inner part of the adventitia close to the media of the arterial and venous vessels and among the intracavernous smooth muscle cells. IR-NPY nerve fibers were less abundant in veins than in arteries. Positive somata were not observed in the penises. At the ultrastructural level, IR-NPY were localized exclusively in large, dense granules of nerve terminals by means of the postembedding immunogold technique. In the deep dorsal vein, IR-NPY nerve fibers were also located in the media formed by an outer circular and an inner longitudinal layer. In the intracavernous and dorsal arteries, they showed the highest density in the inner part of the adventitia. In the corpora cavernosa and in the corpus spongiosum, IR-NPY nerve processes were intermingled between the smooth-muscle fibers around the sinusoid spaces. IR-NPY nerve fibers were present in the cavernous nerves close to the central arteries. The urethra did not show any IR-NPY-positive nerve fibers. This peculiar distribution of IR-NPY nerve fibers suggested that they could participate in regulating arterial and venous blood flow and intracavernous smooth-muscle tone. NPY may therefore be of importance in some of the mechanisms of penile erection especially during detumescence.
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    URL: http://dx.doi.org/10.1007/BF00220018
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    Implantation of cultured thymic fragments in congenitally athymic (nude) rats (1988)
    Springer
    Cell & tissue research 254 (1988), S. 283-294 
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    ISSN: 1432-0878
    Keywords: Thymus ; Cultured thymic fragments ; Epithelial cells ; Microenvironment ; Ultrastructure ; Rat (nude)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cultured thymic fragments correspond to the thymic microenvironment depleted of lymphocytes and dendritic cells. When these fragments are implanted under the kidney capsule of congenitally athymic rats, lymphocytes and dendritic cells of host origin enter the graft and induce thymus-dependent immunity in the recipient. This paper describes the ultrastructure of the fragments and the changes that occur during the restoration of normal thymic architecture. At the end of the culture period of 6–9 days and in the early stages after implantation, the grafts consist of keratin-containing epithelial cells of unusual morphology that can be labelled with antibodies raised against the epithelium of the mid/deep cortex and the subcapsule/medulla. Normal thymic architecture develops, including nerves and blood vessels, as lymphocytes populate the environment, and by 4–6 weeks the epithelial cells are the same phenotypically and ultrastructurally as those found in normal rat thymus. However, some areas without lymphocytes still contain the atypical epithelial cells seen before implantation. Large multinucleated giant cells are also present with a few associated epithelial cells of subcapsular/medullary phenotype. In conclusion, the cultured thymic fragments contain a hitherto unknown precursor epithelial cell with an atypical ultrastructure and phenotype that is not seen in normal development.
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    An ultrastructural study of mitosis and cytokinesis in normal ‘resting’ human breast (1988)
    Springer
    Cell & tissue research 252 (1988), S. 581-587 
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    ISSN: 1432-0878
    Keywords: Normal resting breast ; Ultrastructure ; Mitosis ; Cytokinesis ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The parenchyma of the normal “resting” human breast was examined by electron microscopy to characterize the cells undergoing mitosis and the mechanism by which the normal tissue architecture is maintained during this process. In this study of 112 mitotic cells, it was found that the mitotic cells were luminally positioned, polarised epithelial cells with no evidence of myoepithelial cell division. Ultrastructurally, the nuclear and cytoplasmic changes were consistent with previous reports of mitosis in other tissues. However, unlike all previous reports, two specific orientations of the nuclear spindle and thus the planes of cytokinesis were observed. In a few cases the spindle formed parallel to the lumen and division resulted in two luminally positioned daughter cells. However, in the majority of mitotic cells the spindle was approximately at right angles to the lumen and this orientation resulted in a luminally and a basally positioned daughter cell. It is proposed that the abnormally positioned basal daughter cell could develop into a myoepithelial cell or undergo deletion (apoptosis). Thus the two orientations of mitosis may explain the mechanism by which the epithelial and myoepithelial cell populations were maintained by a single progenitor cell without disrupting the integrity of the tissue architecture.
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    Separation and maturation of gonadotrophs from 2A8 clonal cells in vitro (1978)
    Springer
    Cell & tissue research 189 (1978), S. 31-40 
    Details
    ISSN: 1432-0878
    Keywords: Pituitary cell clone ; LHRH-Sepharose ; Gonadotrophs ; Hypertrophy ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 2A8 clonal cells derived from the epithelium of Rathke's pouch of fetal rats were cultured in growth medium supplemented with fresh rat serum, median-eminence extract and l-thyroxine. Then, in order to isolate gonadotrophs, cyanogen bromide-activated Sepharose which was conjugated with LHRH (LHRH-Sepharose) was added to the culture medium. Fourteen days after incubation of 2A8 cells with LHRH-Sepharose, agranular and granular cells were rapidly bound to LHRH-Sepharose when fresh serum had previously been added in the medium. The cytoplasm of granular cells that were bound to LHRH-Sepharose contained spherical secretory granules (200–250 nm in diameter). These cells were similar in morphology to the FSH and LH gonadotrophs described by Kurosumi (1968). Moreover, many of them appeared as hypertrophied cells that resembled “castration” cells. These results demonstrate that LHRH conjugated to Sepharose can be used to separate gonadotrophs from other 2A8 cells, and it is suggested that the hypertrophy of some cells might be due to persistent stimulation by LHRH which is likely bound to receptors on the cell membrane.
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    URL: http://dx.doi.org/10.1007/BF00223119
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    The ultrastructure of the herring bodies in rats subjected to different experimental conditions (1978)
    Springer
    Cell & tissue research 189 (1978), S. 41-51 
    Details
    ISSN: 1432-0878
    Keywords: Herring bodies (rat) ; Colchicine ; Cold ; Neurosecretion ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A study of the morphology of Herring bodies of the posterior pituitary lobe of rats treated with colchicine and/or exposed to low temperatures has been performed. After treatment with colchicine (20 μg in distilled water injected intracisternally) a predominance of Herring bodies with a large number of small “synaptic-like” vesicles surrounded by neurosecretory granules is found. Exposures to low temperature (4–6° C) result in an increase in the neurosecretory material and the Herring bodies show many neurosecretory granules of different densities. After treatment with colchicine and subsequent exposure to low temperatures, the Herring bodies are characterized by having a great number of autophagic bodies which become more numerous as the length of the exposure is increased; later autophagic vacuoles and lamellar bodies become evident.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223120
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    The ultrastructure and histochemistry of the mesenteric connective tissue of the cockroach Periplaneta americana L. (Insecta, Dictyoptera) (1978)
    Springer
    Cell & tissue research 189 (1978), S. 91-107 
    Details
    ISSN: 1432-0878
    Keywords: Connective tissue sheath ; Periplaneta ; Ultrastructure ; Histochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé La gaine conjonctive épaisse entourant l'intestin moyen de la Blatte Periplaneta americana a été étudiée en faisant appel à la microscopie photonique, électronique et l'histochimie. Cette couche conjonctive, reliée à l'épithélium mésentérique par une lame basale, traversée par des faisceaux musculaires, des trachées et des nerfs, contient de très nombreuses fibrilles de collagène, des fibrilles élastiques, des fibroblastes et des hémocytes. Au cours des premiers stades le matériel conjonctif est élaboré par des fibroblastes. Différentes réactions, en particulier le bleu alcian, la métachromasie et les digestions enzymatiques ont montré la présence de glycosaminoglycanes. La présence d'acide hyaluronique à tous les stades, l'apparition et l'augmentation des composés sulphatés ainsi que la présence de glycoprotéines ont été mises en évidence.
    Notes: Summary The thick layer of collagenous connective tissue around the mesenteron of the cockroach Periplaneta americana has been examined by light microscopy, electron microscopy and histochemical techniques. This sheath, connected to the mesenteric epithelium by a basal lamina and traversed by longitudinal and circular musculature, tracheae and nerves, contains numerous collagen fibrils, elastic fibers, fibroblasts and rare hemocytes. Development starts during the first instars with the production of connective tissue material by fibroblasts. Glycosaminoglycans have been observed with the use of various histochemical reactions, in particular alcian blue staining, metachromasia and enzymatic digestion. The reactions indicate the presence of hyaluronic acid in the various instars, the appearance and increase of sulphated components during development, and the presence of neutral glycoproteins.
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    URL: http://dx.doi.org/10.1007/BF00223123
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    An ultrastructural study of periderm granules in the regenerating feather of the jungle fowl (1978)
    Springer
    Cell & tissue research 192 (1978), S. 319-326 
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    ISSN: 1432-0878
    Keywords: Periderm granules ; Regenerating feather ; Ultrastructure ; Jungle fowl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Periderm granules in the support cells of regenerating feathers of mature male Jungle Fowls were studied ultrastructurally and histochemically. Histochemical results showed the absence of carbohydrate and lipid, and the presence of protein in the periderm granules. The periderm granules were measured at successive levels of feather regeneration. The mean size of the periderm granules increased significantly as the regenerating feather matured, and this observation was suggestive of a storage function, perhaps of surplus or waste protein. The cells in which the periderm granules are found also contain glycogen. There are numerous desmosomal junctions on their interdigitating plasma membranes. These transient cells may collect waste, provide nutrition, and serve as a protective barrier for the definitive cells of the regenerating feather.
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    URL: http://dx.doi.org/10.1007/BF00220749
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    A further type of transient cytoplasmic organelle in human spermatids (1978)
    Springer
    Cell & tissue research 192 (1978), S. 359-361 
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    ISSN: 1432-0878
    Keywords: Spermatids ; Human ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Osmiophilic granules with surrounding vesicles resembling flower-like structures occur transiently during the differentiation of human spermatids. These organelles are incorporated into the residual bodies when mature spermatids are released from the germinal epithelium.
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    URL: http://dx.doi.org/10.1007/BF00220752
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    Ultrastructure of the ovarian medulla in the newly hatched chick treated with human chorionic gonadotropin (1988)
    Springer
    Cell & tissue research 253 (1988), S. 665-670 
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    ISSN: 1432-0878
    Keywords: Ovary ; Steroid-secreting cells ; Ultrastructure ; Chorionic gonadotropin ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural characteristics of the ovarian medulla of the newly hatched white leghorn chick were studied in control animals and compared with chicks that were treated with human chorionic gonadotropin during embryonic development. The ovarian medulla was mainly occupied by epithelial cells which formed cords or islets surrounded by a basal lamina. Within this epithelial compartment, steroidogenic cells, poorly differentiated cells and a lacunary system could be recognized. When chicks were treated with human chorionic gonadotropin, steroidogenic cells became discernible; there was an increment in the amount of cytoplasm and the area of mitochondria. Poorly differentiated cells exhibited signs of stimulation, and transitional images suggested the transformation of these cells into steroidogenic cells. The epithelial cells of the lacunar system also displayed stimulated cytoplasmic organelles. Evidence was supplied suggesting that relatively undifferentiated cells persist in the ovarian medulla until hatching and can develop into steroidogenic cells under gonadotropic stimulation.
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    URL: http://dx.doi.org/10.1007/BF00219758
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    Electron-microscopic immunocytochemistry of 5-hydroxytryptamine in the ascidian endostyle (1988)
    Springer
    Cell & tissue research 253 (1988), S. 137-143 
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    ISSN: 1432-0878
    Keywords: Endostyle ; Ultrastructure ; Immunocytochemistry ; 5-Hydroxytryptamine ; Granules ; Ciona intestinalis ; Corella parallelogramma, (Tunicata) ; Ascidia mentula (Tunicata)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cellular and subcellular distribution of serotonin (5-hydroxytryptamine, 5-HT) in the endostyle of three species of ascidians, Ciona intestinalis, Corella parallelogramma, Ascidia mentula, was studied by light-(immunoperoxidase) and electron-microscopic (immunogold) immunocytochemistry. At the light-microscopic level 5-HT-like immunoreactivity (5-HT-LI) was exclusively found in cells located in the lateral portion of the endostyle, between zone 7, known to have iodinating capacity, and zone 8, which consists of ciliated cells. At the electron-microscopic level, the 5-HT-immunoreactive cells were found to correspond to cells containing polymorphous, dense granules, 100–300 nm in diameter. The granules were located in the supranuclear cytoplasm facing the endostyle lumen as well as in the infranuclear cytoplasm facing the extracellular space. Quantification showed that the 5-HT-LI was considerably higher (13–67 times) in cytoplasmic areas containing granules as compared to areas devoid of granules. Most, but not all, of the 5-HT-LI was associated with the dense core of the granules. In conclusion, serotonin-containing cells are located in the peripheral portion of the endostyle, between zones 7 and 8. Serotonin is stored in cytoplasmic granules that are present both in the apical and basal cytoplasm. This suggests the possibility that the cells are bipolar and secrete serotonin both in a basal direction to the extracellular space, and in an apical direction to the pharyngeal lumen.
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    URL: http://dx.doi.org/10.1007/BF00221748
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    Effect of live and heat-killed bacteria on the secretory activity of Paneth cells in germ-free mice (1988)
    Springer
    Cell & tissue research 251 (1988), S. 87-93 
    Details
    ISSN: 1432-0878
    Keywords: Paneth cells ; Ultrastructure ; Morphometry ; Facultative anaerobes ; Germ-free mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Germ-free mice were given live or heat-killed facultative anaerobes, and the ultrastructure of ileal Paneth cells was quantitatively examined with special reference to secretory granules showing a bipartite substructure (central core and peripheral halo). After administering live or heatkilled bacteria, there was a decrease in the area occupied by the cores of secretory granules in Paneth cells, and exocytosed core material was observed in the crypt lumen. There were no changes in the area occupied by the halo of secretory granules. None of the examined Paneth cells phagocytosed bacteria. It is concluded that certain bacteria may affect the secretion of antibacterial agents contained in the secretory granules of Paneth cells.
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    URL: http://dx.doi.org/10.1007/BF00215451
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    Ultrastructural changes in the fat body of adult female Aedes aegypti in relationship to vitellogenin synthesis (1978)
    Springer
    Cell & tissue research 186 (1978), S. 499-506 
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    ISSN: 1432-0878
    Keywords: Fat body ; Aedes aegypti ; Vitellogenin ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the fat body of Aedes aegypti was followed from emergence through a blood meal. Changes in the volume of protein granules and lipid droplets were also examined. The relationship of these events to the known endocrinology of vitellogenin synthesis in mosquitoes is discussed.
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    URL: http://dx.doi.org/10.1007/BF00224938
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    Leptomeric fibrils and T-tubule desmosomes in the Z-band region of the mouse heart papillary muscle (1978)
    Springer
    Cell & tissue research 188 (1978), S. 205-215 
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    ISSN: 1432-0878
    Keywords: Myocardium ; Mouse ; Ultrastructure ; Leptofibrils ; Desmosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The papillary muscle of the heart of adult white mice is investigated. Intrafibrillarly located leptomeric fibrils, frequently encountered in the Z-band region of the myofibrils. The leptomeric fibrils are always running in a transverse direction and often in close proximity to the transverse tubules (which are also located at this level). There seems to be a close connection between the dense striae of the leptofibrils and the Z-bands of ordinary myofibrils. The leptomeric fibrils are spindle-shaped and have a length varying between 0.6 and 1.2 μm. The banding periodicity of the fibrils is approximately 0.16 μm. Occasionally desmosomes are observed in the T-tubule system.
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    URL: http://dx.doi.org/10.1007/BF00222631
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    Three-dimensional organization of the plasmalemmal vesicular system in directly frozen capillaries of the rete mirabile in the swim bladder of the eel (1988)
    Springer
    Cell & tissue research 254 (1988), S. 17-24 
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    ISSN: 1432-0878
    Keywords: Endothelium ; Swim bladder ; Capillaries ; Vesicles ; Ultrastructure ; Cryofixation ; Anguilla rostrata (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Several recent studies comparing chemically fixed and cryofixed endothelium have indicated that glutaraldehyde fixation may result in increases in the population of “vesicles” in the cytoplasm. Other reports based on ultrathin serial-section reconstruction of chemically fixed endothelium have revealed that the vesicular system is comprised of interconnected membranous compartments, which are ultimately continuous with either cell surface but do not extend across the endothelial cell. In this study, we have investigated the three-dimensional organization of the vesicular system in directly frozen, freeze-substituted capillaries of the rete mirabile from the swim bladder of the eel, specifically using the same block of embedded capillaries in which frozen capillaries had previously been found to contain less “vesicles” than chemically fixed capillaries. The results show that essentially all vesicles remain inter-connected with each other and are part of two separate sets of invaginations from the luminal and abluminal cell surface like in chemically fixed tissue. Any increase in vesicle number resulting from glutaraldehyde fixation does not affect the overall three-dimensional organization of the vesicular system in these endothelial cells.
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    URL: http://dx.doi.org/10.1007/BF00220012
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    Changes in proteins synthesized by rabbit endometrial epithelial cells following primary culture (1988)
    Springer
    Cell & tissue research 252 (1988), S. 123-132 
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    ISSN: 1432-0878
    Keywords: Uterine epithelium ; Cell culture ; Proteins ; Ultrastructure ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Morphological and biochemical changes occurring in rabbit endometrial epithelial cells when placed in culture were investigated. Cells were examined by scanning- and transmission electron microscopy and freeze-fracture. Morphologically, cultured cells are shorter and broader than the columnar epithelial cells in vivo, but retain their polarity as indicated by the presence of apical microvilli and a well-developed junctional belt. To study changes in biochemical function, proteins synthesized by cells in primary culture were analyzed by two-dimensional gel electrophoresis. Proteins were labeled during a 24-h incubation with 35S-methionine and gels examined by fluorography. The pattern of proteins changed after cells had been in culture for 48 h. On day 3 new proteins were synthesized and several protein species labeled during days 1 or 2 of culture, including uteroglobin, no longer appeared. On days 3–8 of culture the protein patterns were similar. Addition of progesterone, estradiol, prolactin, or combinations of these hormones to the culture medium for 24–144 h failed to elicit consistent changes in the pattern of labeled proteins established after 3 days of culture. Minor differences in protein patterns among unrelated cultures appear to have been derived from the original cells of the culture. These results indicate that after 48 h in primary culture, cells grown in vitro resemble endometrial epithelial cells morphologically, but no longer reflect functionally the character of epithelial cells in the uterus.
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    URL: http://dx.doi.org/10.1007/BF00213833
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    Formation of desmosomes and other contact specializations in cultured skin of the frog (Rana esculenta) (1988)
    Springer
    Cell & tissue research 252 (1988), S. 157-163 
    Details
    ISSN: 1432-0878
    Keywords: Frog skin culture ; Desmogenesis ; Interdigitations ; Lamellipodia ; Ultrastructure ; Rana esculenta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Small trypsinized explants from ventral skin of frogs (Rana esculenta) were maintained in culture for 4 days during which a newly formed epithelium differentiated along the cut edges of the dermis. During the first 6 h adjacent cells produced numerous interdigitating lamellipodia. After 2 days, epithelial polarity was restored by the formation of zonulae occludentes and the epithelial cells were joined by a few small newly formed desmosomes and by numerous interdigitations. Bipartite junctional complexes consisting of a zonula occludens, followed by a series of typical desmosomes, and characteristic of adult frog epidermis were formed only after 4 days. When cultured in the presence of an inhibitor of protein synthesis (cycloheximide) the trypsinized epidermis no longer formed desmosomes. Therefore pools of one or more crucial desmosomal proteins must be very low or non-existent. However, cycloheximide did not prevent the formation of cell contact specializations, consisting of a highly developed system of complex lamellar interdigitations, between adjacent cells.
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    URL: http://dx.doi.org/10.1007/BF00213837
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    Morphology of smooth muscle cells in the rat thoracic duct (1988)
    Springer
    Cell & tissue research 251 (1988), S. 243-248 
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    ISSN: 1432-0878
    Keywords: Thoracic duct ; Smooth muscle cell ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The three-dimensional cytoarchitecture and ultrastructure of the smooth muscle cells in the wall of the rat thoracic duct were investigated by scanning and transmission electron microscopy. The muscle layer basically consists of a single layer of circularly arranged cells. The smooth muscle cell is fusiform or ribbon-like in shape, as in veins or venules with a similar or smaller diameter. Connections by spinous processes are observed between adjacent muscle cells along their length. Spot-like membrane contacts frequently occur in areas where facing membranes are closely apposed. These are thought to be gap junctions and may be responsible for electrical coupling and mechanical attachment. Large invaginations arranged regularly in rows on the surface of the smooth muscle cells can be observed. These invaginations are closely associated with a flattened sarcoplasmic reticulum, and caveolae tend to open into the invaginations.
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    Atropine inhibits the degranulation of Paneth cells in ex-germ-free mice (1988)
    Springer
    Cell & tissue research 253 (1988), S. 397-402 
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    ISSN: 1432-0878
    Keywords: Paneth cells ; Ultrastructure ; Morphometry ; Atropine ; Germ-free/Ex-germ-free ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Previous studies have shown that the secretory products of Paneth cells contain antibacterial agents (lysozyme, IgA) that are affected by the bacterial milieu in the intestine. To investigate whether Paneth-cell secretion is controlled via cholinergic mechanisms, the ultrastructure of Paneth cells was studied in four animal groups: (1) germfree (GF) control mice (Jcl: ICR [GN], male, 13 weeks old), (2) GF mice injected subcutaneously with atropine sulfate (200 mg/kg body weight, dissolved in physiological saline 20 mg/ml), (3) ex-GF mice inoculated with feces from specific-pathogen-free (SPF) mice, and (4) ex-GF mice injected with atropine and inoculated with feces from SPF mice. In ex-GF mice inoculated with feces, 70–90% of the Paneth cells showed fewer secretory granules than those from GF mice (p〈0.01). Approximately 30% of the Paneth cells had a large vacuole (3–10 μm diameter) in the apical cytoplasm. Exocytosed electron-dense material from secretory granules was observed in a few crypt lumens. In ex-GF mice inoculated with feces and given atropine, about 90% of the Paneth cells contained numerous secretory granules, like those in GF control mice, but vacuolated Paneth cells and exocytotic figures were rare; thus the secretion of Paneth cells was blocked by atropine. It is therefore possible that the bacterial milieu in the intestine affects the secretory activity of Paneth cells via cholinergic mechanisms.
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    URL: http://dx.doi.org/10.1007/BF00222296
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    Lymphocytes of the intestinal mucosa of chickens (1988)
    Springer
    Cell & tissue research 251 (1988), S. 189-195 
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    ISSN: 1432-0878
    Keywords: Lymphocytes ; Epithelium ; Mast cells ; Granular leukocytes ; Basophils ; Ultrastructure ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Examination, by light and electron microscopy, of the morphology and the staining properties of intraepithelial lymphocytes from the intestine of the chicken revealed a population of lymphoid cells, of which a proportion (up to 20%) is granulated. The majority of cells were immunoreactive with anti-T cell serum and can therefore be considered to be related to T-lymphocytes, but they did not proliferate when cultured with phytohaemagglutinin. The granulated cells were identical to those previously designated globule-containing leukocytes, but were distinct from mast cells in their morphology, staining reactions and the stability of the granules in different fixatives and buffers.
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    Structural changes produced in Kupffer cells in the rat liver by injection of lipopolysaccharide (1988)
    Springer
    Cell & tissue research 251 (1988), S. 205-214 
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    ISSN: 1432-0878
    Keywords: Kupffer cells ; Granulocytes ; Ultrastructure ; Lipopolysaccharide ; Liver ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of Kupffer cells has been studied at various times after an intravenous injection of lipopolysaccharide of Salmonella abortus equii. The most prominent effects were: an increase in the number and dimensions of phagocytic vacuoles (often containing ingested LPS and neutrophilic granulocytes); mitochondrial damage, including disintegration of the matrix and cristae; an increase in the amount of dilated, lucent rough endoplasmic reticulum; presence of fat droplets in the cytoplasm. Five days after injection of lipopolysaccharide, the Kupffer cells had resumed their normal ultrastructure. Several minutes after injection of lipopolysaccharide, platelets adhered to the Kupffer and endothelial cells. Between one and six hours, neutrophilic granulocytes accumulated in the liver sinusoids. The resulting obstruction of the hepatic microcirculation most probably affected cellular ultrastructure by ischaemia. At three days, the number of Kupffer cells was doubled, and increased further at later time intervals.
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    Melanophore death and disappearance produces color metamorphosis in the polychromatic Midas cichlid (Cichlasoma citrinellum) (1988)
    Springer
    Cell & tissue research 253 (1988), S. 9-14 
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    ISSN: 1432-0878
    Keywords: Chromatophores ; Color change ; Ultrastructure ; Melanophores ; Macrophages ; Xanthophores ; Cichlasoma citrinellum (Teleostei: Cichlidae)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We describe the histological basis of color metamorphosis in the polychromatic Midas cichlid, Cichlasoma citrinellum. Eight percent of the individuals in a natural population transform from gray with black markings to orange, simultaneously losing their ability to adjust coloration in response to background and social context. This trait is inherited. Light- and electron microscopy revealed that this transformation is a two-step process. First, the melanophores die, then macrophage-like cells remove the debris. As a result of this initial process, the underlying xanthophores become visible, producing the orange coloration. A similar process may occur in individuals that further transform to white, or go directly from gray to white.
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    URL: http://dx.doi.org/10.1007/BF00221733
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    Cortical cytoskeleton of the flagellateProteromonas lacertae: Interrelation between microtubules, membrane and somatonemes (1988)
    Springer
    Protoplasma 142 (1988), S. 46-54 
    Details
    ISSN: 1615-6102
    Keywords: Cytoskeleton ; Plasma membrane ; Microtubules ; Ultrastructure ; Freeze-fracture ; Flagellates ; Proteromonas lacertae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The anterior half of the cell surface of the parasitic flagellateProteromonas lacertae is corrugated while the posterior half is covered by hair-like appendages, called somatonemes. In the anterior part, the cortical microtubules are lined by a zig-zag shaped microfibril. Here, these two structures seem to be separated from the plasma membrane. In the posterior half of the cell the somatonemes, analogous to the mastigonemes of chrysophytes, are anchored to the cortical microtubules by paired small deposits of dense material. This was clearly demonstrated by Triton X 100 treatment which solubilized the plasma membrane but left the somatonemes attached to the cortical microtubules. Freeze-fracture images revealed the alignment of clustered intramembrane particles on the P-face of the plasma membrane which correspond to the attachment sites of the somatonemes, seen as dots in thin sections. The ER-derived membrane-associated somatonemes are probably linked to the cortical microtubules by anchoring proteins which are part of the plasma membrane.
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    URL: http://dx.doi.org/10.1007/BF01273225
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    Observations of soybean root meristematic cells in response to heat shock (1988)
    Springer
    Protoplasma 144 (1988), S. 1-9 
    Details
    ISSN: 1615-6102
    Keywords: Heat shock ; Soybean root ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Soybean seedlings (Glycine max) were incubated in narrow temperature regimes to study the effects of heat shock on cell structures. The incubation temperatures used were as follows: 1. 28 °C (2h); 2. 40 °C (2h); 3. 45 °C (2h); 4. 40 °C (2h)→45 °C (2h); 5. 47. 5 °C (10 min); 6. 40 °C (2h)→47. 5 °C (10 min). Both optical and electron micrographs were taken of the different tissues of root meristems as they responded to heat shock. Cells of roots heated to 45 °C (2h) or 47.5 °C (10 min) with lethal treatment showed drastic heat injuries:e.g., membrane damage, coagulated plasmolysis, protoplasmic contraction, and leakage of cell content. Nucleolar segregation occurred in cells treated at both lethal and supraoptimal temperatures. Seedlings preincubated at 40 °C (2 h) became thermo-tolerant to lethal temperature treatment of 45 °C (2 h) or 47.5 °C (10 min), by protecting the plasmalemma, mitochondria, plastids and nuclei from heat damage. Without preincubation, however, these structures were destroyed.
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    URL: http://dx.doi.org/10.1007/BF01320274
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    Metabolism of P-particles (polysaccharide particles) in mature pollen grains ofEryngium campestre L. (Apiaceae) (1988)
    Springer
    Protoplasma 146 (1988), S. 65-71 
    Details
    ISSN: 1615-6102
    Keywords: Apiaceae ; Eryngium campestre ; Metabolism ; Pollen grain ; P-particle ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The metabolism of P-particles (polysaccharide particles) was investigated in mature pollen grains ofEryngium campestre L. Numerous P-particles, originating from dictyosome activity, are found to be accumulated near the apertures, followed by mitochondria. A single layer of ER profiles seems to prevent the fusion of the P-particles with the intine. Instead of this, they fuse with each other forming nonmembrane-bounded polysaccharide-aggregates, which subsequently change their granulated structure to an amorphous. Mitochondria together with small vesicles are involved in the conversion-process. The so formed wall precursors pass through the ER and fuse into the intine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01405914
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  • 96
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    Preliminary observations on the formation of the male germ unit in pollen tubes ofCyphomandra betacea sendt. (1988)
    Springer
    Protoplasma 147 (1988), S. 55-63 
    Details
    ISSN: 1615-6102
    Keywords: Generative cell ; Sperm cell ; Treetomato ; Ultrastructure ; Vegetative nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The structure of the generative cell and its association with the vegetative nucleus in the pollen tube ofCyphomandra betacea Sendt. were observed with the electron microscope. The generative cell, bounded by its own plasma membrane and the inner plasma membrane of the vegetative cell, possesses the cytoplasmic extension which lies within the embayments of a vegetative nucleus. The generative cell contains the normal complement of organelles and, especially, microtubules which cluster into several groups adjacent to the plasma membrane, oriented along the longitudinal axis of the cell. In the pollen tube reaching the lower end of the style aftersemivivo pollination, both of the sperm cells are elongated and polyribosomes and microtubules are the outstanding feature in the cytoplasm. The two sperm cells are connected by a common transverse cell wall, while cytoplasmic channels exist in both the periplasm of the two sperm cells and the transverse wall. The leading sperm cell (Svn) is closely associated with the vegetative nucleus. Thus the present study demonstrates the existence of the male germ unit in the pollen tube ofC. betacea. The possible cytoplasmic continuity between the sperm cells and between the gametes and vegetative cell is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01403877
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  • 97
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    Morphology ofEntomophthora muscae protoplasts grownin vitro (1988)
    Springer
    Protoplasma 146 (1988), S. 166-173 
    Details
    ISSN: 1615-6102
    Keywords: Entomophthorales ; Entomophthora muscae ; Ultrastructure ; Cytochemistry ; Protoplast ; in vitro growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Entomophthora muscae (C.) Fres. can be grownin vitro as protoplasts. Light and electron microscopical studies of thein vitro developed protoplasts have demonstrated the absence of an organized wall over the protoplasmic Con A-positive membrane at all stages of growth. The cytological organization is typical of the Entomophthorales with condensed chromatin in the interphase nuclei and small eccentric metaphase spindles. Long strands of endoplasmic reticulum, microubules and vesicles surrounding the plasmalemma may be involved in maintaining the precise shape ofE. muscae protoplast. Starvation of the fungus induces the formation of hyphal bodies after deposition of Con A- and WGA-positive wall material at the plasmalemma surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01405926
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  • 98
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    Dynamics of the microtubular cytoskeleton in the green algaAphanochaete magna (Chlorophyta). I. Late mitotic stages and the origin and development of the phycoplast (1988)
    Springer
    Protoplasma 142 (1988), S. 176-187 
    Details
    ISSN: 1615-6102
    Keywords: Aphanochaete ; Astral microtubules ; Immunofluorescence ; Phycoplast ; Spindle breakdown ; 3-D reconstruction ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The spatial and temporal organization of the microtubular cytoskeleton at the transitional stage of mitosis and cytokinesis has been studied in the chaetophoralean green algaAphanochaete magna using indirect immunofluorescence light microscopy and transmission electron microscopic analysis of serial sections including computer-aided three-dimensional reconstruction. At late mitosis, elaborate asterlike microtubule systems including bundles interconnecting both centriolar regions are present. These systems disappear a the onset of interzonal spindle disintegration. The incipient phycoplast consists of a star-shaped microtubule assemblage projecting from the intact interzonal spindle. It develops strongly at the time of spindle disintegration, later on it becomes compressed by daughter nuclei movement. Cell plate formation is associated with a two-dimensional phycoplast. Phycoplast microtubules remain for a while associated with the completed cross wall but finally they depolymerize. The general occurrence of astral microtubule systems (includingA. magna) is evaluated. The subsequent developmental stages of the phycoplast, formation, maturation and depolymerization, are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01290874
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  • 99
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    Ultrastructural aspects of the hyphal tip ofSclerotium rolfsii preserved by freeze substitution (1988)
    Springer
    Protoplasma 146 (1988), S. 143-149 
    Details
    ISSN: 1615-6102
    Keywords: Hyphal tip ; Ultrastructure ; Freeze substitution ; Sclerotium rolfsii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The hyphal tip ofSclerotium rolfsii was examined after fixation by freeze substitution. The Spitzenkörper consisted of a dense mass of apical vesicles and microvesicles surrounding a vesicle-free zone. Linear arrangements of microvesicles were occasionally observed within the Spitzenkörper. Abundant microfilaments were seen within the Spitzenkörper region, often in close association with apical vesicles and microvesicles. Microtubules passed through the Spitzenkörper and terminated at the plasmalemma at the extreme hyphal apex. Filasomes were mostly observed within the apical region and were in close proximity to the plasmalemma. Rough ER, mitochondria, microtubules, and vacuoles were abundant in the subapical region and were usually oriented parallel to the long axis of the hypha. Ribosomes were aligned on the outer surfaces of mitochondria. Golgi body equivalents were observed throughout the subapical region and appeared as inflated cisternae of varying shapes and electron opacities. Relationships to other basidiomycetous hyphal tip cells are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01405923
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  • 100
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    Electronic Resource
    The effect of low pH and aluminum on the olfactory organ of rainbow trout, Salmo gairdneri (1988)
    Springer
    Environmental biology of fishes 22 (1988), S. 69-77 
    Details
    ISSN: 1573-5133
    Keywords: Acid ; Metals ; Ultrastructure ; Olfaction ; Electrical response ; Pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The effects of acid ((H2SO4) and aluminum AIKSO4 in acidified water on rainbow trout, Salmo gairdneri, olfactory organ were examined using scanning electron microscopy and electrophysiology. Exposure to pH 4.7 resulted in an increase in the number of mucus droplets over parts of the olfactory epithelium, primarily along the ridges of the secondary folds. The addition of aluminum (5.0, 9.5, 20.0 µmol · 1−1) at pH 4.7 resulted in loss of receptor cell cilia, irregularly shaped olfactory knobs, clumped microvilli and swellings on microridge cells. Electrical responses recorded from the olfactory nerve in response to the amino acid L-serine were similar to controls in fish exposed to acidified water. When fish were exposed to acidified water and aluminum the response was depressed. These morphological and electrophysiological changes could be used to indicate metal-induced stress in fish from natural ecosystems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00000544
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