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  • Electron microscopy  (27)
  • Modelling
  • Triticum aestivum
  • Springer  (44)
  • Cell Press
  • 2005-2009
  • 1980-1984  (44)
  • 1950-1954
  • 1982  (44)
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  • 2005-2009
  • 1980-1984  (44)
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 260 (1982), S. 564-569 
    ISSN: 1435-1536
    Schlagwort(e): lin. Polyethylene ; Single crystals ; Heat of Fusion ; DSC ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Recently published results for solution crystallized PE single crystals have shown, that the experimental heat of fusionΔH * is higher, if the solvent is exchanged to silicon oil (oil suspension samples) as compared with dried mats. This has been interpreted by the collapse of the original hollow pyramids during drying, inducing lateral defects within the lamellae. The present investigation does not confirm this unexpected result.ΔH * of dried mats (T c 66 to 91 °C) and of the corresponding oil suspension samples agree within the rather small limits of experimental error. The crystallinities as derived fromΔH *, density or WAXS are in excellent agreement. SEM micrographs of cold fractured dried mats show their spongy macromorphology, but TEM micrographs of stained ultra-thin sections reveal the lamellar morphology of the walls, consisting of curved lamellae and stacked hollow pyramides. If a dried mat is sintered at room temperature, a dense transparent film is obtained with a rather regular stacked morphology of large flat lamellae.ΔH * of these films agrees with that of the original mat.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Development genes and evolution 191 (1982), S. 205-207 
    ISSN: 1432-041X
    Schlagwort(e): Chitin inhibition ; Nikkomycin ; Cuticle ; Electron microscopy ; Epilachna varivestis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The nucleoside antibiotic nikkomycin has proved to be an effective inhibitor of chitin synthesis in the Mexican bean beetleEpilachna varivestis. Ultrastructural investigations show defects in the procuticular area after nikkomycin application which suggest the complete absence of chitin. A cuticle like this is inflexible and too brittle to satisfy its normal function as an exoskeleton. The individuals are not able to free themselves from the exuvia and finally die. Therefore nikkomycin seems to be a potential insecticide with high specifity.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 132 (1982), S. 10-13 
    ISSN: 1432-072X
    Schlagwort(e): Calcofluor White ; Cell wall structure ; Chlorella ; Electron microscopy ; Protoplast ; Ruthenium Red
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Among 12 strains ofChlorella ellipsoidea, C. vulgaris, andC. saccharophila tested, 4 strains (1,C. ellpsoidea; 2,C. vulgaris; 1,C. saccharophila) formed osmotically labile protoplasts after treatment with mixtures of polysaccharide degrading enzymes. The relationship between enzymatical digestibility and structure or composition ofChlorella cell walls were studied by electron microscopy and staining techniques with some specific dyes. The cell wall structures of the 12Chlorella strains were grouped into three types: (1) with a trilaminar outer layer, (2) with a thin outer monolayer, and (3) without an outer layer. Protoplasts were formed only from the strains with a cell wall of Type 2. In the strains with a cell wall of Type 1, the outer layer protected the inner major microfibrillar layer against enzymatic digestion. The cell wall of Type 3 was totally resistant to the enzymes; the chemical composition of the cell wall would be somewhat different from that of other types.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 133 (1982), S. 97-99 
    ISSN: 1432-072X
    Schlagwort(e): Cyanobacteria ; Thylakoid centers ; Photosynthetic membranes/thylakoids ; Membranes ; Membrane biogenesis ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract An ultrastructural study of four cyanobacteria (Anabaena cylindrica, Dermocarpa violaceae, Gleocapsa alpicola, Pleurocapsa minor) indicates the presence of previously undescribed thylakoid centers from which photosynthetic membranes (thylakoids) radiate. These peripherally located thylakoid centers are cylinders 30 nm wide by 320 nm long, consisting of globular subunits oriented in nonparallel stacked arrays. Thylakoids are attached to the outer surface of the cylinder along its longitudinal axis. Thylakoid centers appear to be functionally significant due to their structure, location and thylakoid association.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 131 (1982), S. 116-123 
    ISSN: 1432-072X
    Schlagwort(e): Cell wall ; Wall degradation ; Lysozyme ; Autolysines ; Electron microscopy ; Staphylococcus aureus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In contrast to former findings lysozyme was able to attack the cell walls ofStaphylococcus aureus under acid conditions. However, experiments with14C-labelled cell walls and ribonuclease indicated that, under these conditions, lysozyme acted less as an muralytic enzyme but more as an activator of pre-existing autolytic wall enzymes. Electron microscopic studies showed that under these acid conditions the cell walls were degraded by a new mechanism (i.e. “attack from the inside”). This attack on the cell wall started asymmetrically within the region of the cross wall and induced the formation of periodically arranged lytic sites between the cytoplasmic membrane and the cell wall proper. Subsequently, a gap between the cell wall and the cytoplasmic membrane resulted and large cell wall segments became detached and suspended in the medium. The sequence of lytic events corresponded to processes known to take place during wall regeneration and wall formation. In the final stage of lysozyme action at pH 5 no cell debris but “stabilized protoplasts” were to be seen without detectable alterations of the primary shape of the cells. At the same time long extended ribbon-like structures appeared outside the bacteria. The origin as well as the chemical nature of this material is discussed. Furthermore, immunological implications are considered.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 61 (1982), S. 125-128 
    ISSN: 1432-2242
    Schlagwort(e): Triticum aestivum ; Wheat-phenolics-location
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Using thin-layer chromatography and nulli-tetrasomic and ditellosomic series of Triticum aestivum L. cv. ‘Chinese Spring’, it has been possible to relate the phenolic compounds found in adult plant leaves and 12 day-old seedling leaves with the chromosomes or chromosome arms 1 B, 2 BL, 3 BL, 5 A, 6 AL, 7 B and 7 DS.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 63 (1982), S. 71-73 
    ISSN: 1432-2242
    Schlagwort(e): Triticum aestivum ; Pollen ; Anther culture ; Callus ; Regeneration ; Plantlets
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Pollen shed between 4–8 d from anthers of Triticum aestivum cultured in liquid medium gave rise to calluses. Tillers were harvested at the mid-to late-unicellular pollen stages and chilled for 8 d at 4–5 °C before the anthers were dissected out. Pollen cultures gave about 6 times as many calluses on a per anther basis as anthers cultured on solid medium. With the most productive of 5 cultivars tested, pollen culture results in roughly one callus for each anther used, though the calluses formed by pollen culture were less productive for the regeneration of shoots than calluses derived from anthers cultured on solid medium. The ratio of green to albino shoots is roughly 1∶ 1 for anther cultures but considerably less for pollen cultures.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 63 (1982), S. 121-124 
    ISSN: 1432-2242
    Schlagwort(e): Triticum aestivum ; Grainprotein ; Gene action ; Regression ; Diallel cross
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Diallel crosses between five divergent vulgare wheat cultivars were made in order to evaluate the mode of inheritance and combining ability of grain proteins. Significant differences in grain protein content were found between cultivars and their hybrids. It was established that the inheritance of seed protein in the F1 generation included both additive and non-additive gene action.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 61 (1982), S. 129-133 
    ISSN: 1432-2242
    Schlagwort(e): Interchange ; Chromosome arrangements ; Common wheat ; Triticum aestivum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Chromosome arrangements of twenty-eight cultivars of common wheat, Triticum aestivum L., from or introduced into Spain are compared with that of ‘Chinese Spring’ taken as a pattern. All the cultivars analyzed differ from ‘Chinese Spring’ by one or two reciprocal translocations. When 12 out of 28 cultivars were compared it was concluded that a minimum number of thirteen interchanges are present, involving at least ten different chromosomes of the complement. The interest of a reappraisal of the rôle of interchanges in the evolution of Gramineae is pointed out.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 61 (1982), S. 337-339 
    ISSN: 1432-2242
    Schlagwort(e): Triticum aestivum ; ‘Chinese Spring’ ; Chromosome banding ; Hydrolysis ; Feulgen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Terminal and/or interstitial N-bands were produced on the seven B-genome chromosomes and chromosomes 4 and 7 of the A-genome of Triticum aestivum cv. ‘Chinese Spring’ by a modified BSG technique following a standard Feulgen preparation. The banding was accomplished by modifying the barium hydroxide treatment.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 111 (1982), S. 206-214 
    ISSN: 1615-6102
    Schlagwort(e): Bark beetle ; Sensilla ; Chemoreceptors ; Mechanoreceptors ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The antennal sensilla inI. typographus are almost exclusively confined to the flattened terminal flagellar segment. The sensillar types have distinct distribution patterns in the three areas where they are found. Judging from the ultrastructural characteristics the following functions can be assigned to the sensillar types: chemoreception, single-walled and double-walled sensilla; chemoreception/mechanoreception, terminal-pore sensillum. Moreover there are two types of mechanoreceptors, one of which is connected to a bristle, whereas the other terminates within the cuticle of the flagellar segment.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 69 (1982), S. 311-326 
    ISSN: 1573-5036
    Schlagwort(e): Aeration ; Calcium ; Carbon dioxide ; Ethylene ; Nitrate ; Nitrite ; Nitrous oxide ; Oxygen ; Potassium ; Roots ; Triticum aestivum ; Waterlogging ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary We report a study of the mechanism by which the response of plants to waterlogging can be modified by soil temperature. Wheat was grown initially in well-aerated soil in a controlled environment room before the soil was flooded with aerated, deionized water. The soil temperature was maintained constant in the range 6–18°C while the air temperature was at 14°C. Waterlogging damage was greater in plants at the higher soil temperatures when the plants were compared at the same chronological age. However, when compared at the same growth stage, the response to soil temperature was little differenti.e. plants subjected to waterlogging for a long time at low soil temperatures exhibited a similar reduction in growth and other properties as those subjected briefly at higher temperatures. The concentration of dissolved oxygen in the soil solution declined rapidly at all temperatures, being almost zero after 36 h waterlogging. Temperature affected rates of change of the concentrations of dissolved carbon dioxide, ethylene, nitrous oxide, nitrite, nitrate, calcium and potassium. The importance of soil-and plant-determined properties in the waterlogging response of plants at different temperatures are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 31 (1982), S. 549-564 
    ISSN: 1573-5060
    Schlagwort(e): Triticum aestivum ; wheat ; grain yield ; selection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Four selection experiments were sown: single-row plots with single row-spacing (≃20 cm), single-row plots with double row spacing (≃40 cm), three-row plots and six-row plots both with single row-spacing (≃20 cm). Selection entries were mimiced by 16 different varieties or advanced breeding lines, which were also sown in a yield trial. Each experiment was laid out as a 4-times replicated randomized block design. Row length was 2 m. Alley borders and border-rows of multiple-row plots were harvested separately to evaluate the effects of different harvesting procedures on the selection efficiency. Removal of alley borders was found to be disadvantageous, since the gain in precision was more than offset by the loss in sampled area. Wide spacing of single-row plots improved the selection efficiency in comparison with normal spaced single-row plots. In multiple-row plots the selection efficiency was not improved by harvesting only the central rows. For gross plot yield (= yield of net plot + yield of alley borders) the differences in selection efficiency between the various selection plot-types were explained on the basis of the genetic variance, the environmental variance and the coefficient of genetic correlation with ‘farm’ yield as determined in the yield trial.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 68 (1982), S. 69-74 
    ISSN: 1573-5036
    Schlagwort(e): Azotobacter ; chroococeum ; Derxia ; gumnosa ; Klebsiella ; Nitrogen ; fixation ; Phyllosphere ; Triticum aestivum ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Five highly active N2-fixing strains of Klebsiella isolated from the phyllosphere of tropical plants, KUPBR1, KUPBR2, KUPM, KUP4 and KUP6 along withAzotobacter vinelandii OP,A. chroococcum G40 andDerxia gumnosa were sprayed on the foliage of a high yielding wheat cultivar, Kalyansona. The strains of Klebsiella enhanced dry wt., chrorophyll and nitrogen content, and 1000 grain weight. Grain yield in inoculated plants varied between 19.9 and 25.09 quintals ha−1 against 24.34 quintals with urea. Best results were obtained with KUP4 which when applied at half dose was as effective as 52.5 kg Urea-N ha−1. Azotobacter and Derxia only slightly improved growth and nitrogen content of grain or straw.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 66 (1982), S. 217-223 
    ISSN: 1573-5036
    Schlagwort(e): Azospirillum brasilense ; Biofertilizer ; Spring-wheat ; Triticum aestivum ; Winter-wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Three field experiments were conducted on ten cultivars of winterwheat and four cultivars of springwheat to estimate the growth promoting effect ofAzospirillum brasilense under varying nitrogen doses. Independent of cultivar selection or nitrogen dose a highly significant yield increase could be observed in winterwheat: strains S631 and SpBr14 increased the average grain yield with 9.14% and 14.82% respectively. When the yield components were studied a coinciding increase in ear density could be demonstrated of resp. 10.57% and 13.55%. Less significant results were obtained with springwheat although in one experiment strain SpBr14 significantly increased grain yield. As with winterwheat tillering of the plant was markedly affected by inoculation with both strains. In a companion greenhouse experiment it was found that inoculation with Azospirillum can cause a decrease in the root mass of wheatplants except when strain SpBr14 is used. Therefore it is suggested that the presence of a higher tillering together with an undisturbed nutrient uptake capacity can result in yield increases after inoculation withAzospirillum brasilense.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 66 (1982), S. 433-437 
    ISSN: 1573-5036
    Schlagwort(e): Kaolin spray ; Mulch ; N-application ; Split application ; Triticum aestivum ; Wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Studies revealed that the application of fertilizer nitrogen brought a significant increase in grain and straw yield of wheat. The significant effect was also noticed on such yield contributing characters like number of effective tillers per metre row length, spike length, and number of grains per spike. The increase of nitrogen level from 40 kg/ha to 80 kg/ha also brought a significant increase in yield and yield contributing characters. The application of entire dose of nitrogen at the time of sowing was as good as its split application. The application of nitrogen also influenced the nitrogen concentration of grains whereas, the other treatments did not influence the nitrogen concentration in grains or straw. The nitrogen treatments did not influence the moisture content of soil. The application of mulch or mulch+Kaolin resulted in significantly higher content of soil moisture in 0–15 cm soil depth as compared to control or Kaolin spray alone which was simultaneously reflected in yield and yield contributing characters.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 17
    ISSN: 1573-5060
    Schlagwort(e): Triticum aestivum ; hybrid wheat ; cytoplasmic male sterility ; partial fertility restoration ; Triticum timophecvi ; Puccinia graminis ; stem rust
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Many conventional hard red spring wheat (Triticum aestivum L. em Thell) lines, including several North Dakota cultivars, carry a gene (or genes) which restore partial male fertility to male sterile plants with Triticum timopheevi Zhuk. cytoplasm. Since this gene has no fertility restoration function in T. aestivum cytoplasm, the postulation can be made that it is being retained in conventional lines because of pleiotropic effects, favorable linkages or chance. The research reported in this paper examined these possibilities. Forty F6 lines, derived from a single F2 plant which was heterozygous for a gene (or genes) for partial fertility restoration, were evaluated for two years in a yield trial planted at Fargo, North Dakota. The 40 lines were testcrossed to a male sterile line having T. timopheevi cytoplasm, and the mean seed set of testcrosses was used as a measure of a line's fertility restoration potential. Twenty-seven lines had the gene for partial fertility, and 13 lines apparently lacked this gene. The 40 lines differed for heading date, anther extrusion, plant height, grain yield, 200-kernel weight, test weight, and grain protein percentage. However, comparisons of lines having the restorer gene with those lacking the gene did not provide any obvious explanation for the retention of the partial fertility restorer gene in the breeding stocks of the North Dakota conventional hard red spring wheat breeding program. The possibility that the restorer gene was linked with genes for resistance to stem rust or leaf rust also was evaluated by testing lines for their reaction to several races of rust. No conclusive association was found.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 18
    ISSN: 1573-5060
    Schlagwort(e): Triticum aestivum ; wheat ; glutenin ; SDS-sedimentation test ; SDS-polyacrylamidegel-electrophoresis ; baking quality selection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Gelprotein or SDS-insoluble gel-forming glutenin was isolated from wheat flour by extraction with an aqueous 1.5% SDS solution. Remarkable intervarietal differences were observed both in amount and subunit composition of these proteins. The amount of gelprotein and the SDS-sedimentation volume both proved to be good parameters for the bread-making quality of wheat cultivars. A high correlation was observed between amount of gelprotein and SDS-sedimentation volume. The amount of gelprotein was therefore tentatively assumed to be the essential basis of the SDS-sedimentation test. The subunit composition of the gelprotein was studied by SDS-PAGE after reduction of SS bonds by mercaptoethanol. It was found that the average bread-making quality of wheat cultivars and progeny of the cross Atlas 66 x Atys which possessed subunits 3 and 10, coded for by chromosome 1D, was significantly higher than that of wheat samples possessing subunit 2 and 11, their allelic counterparts.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 19
    ISSN: 1573-5060
    Schlagwort(e): Wheat ; Triticum aestivum ; wheat breeding ; selection ; grain yield ; harvest index
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Aspects of selection for yield and harvest index were investigated by simulating selection using data from random pedigreed F2, F3, F4 and F5 derived lines from two crosses grown in plots at two sites over two years. Improvement in yield through selection was obtained when the response was measured at the same site and in the same year as the selection. Selecting the best 10 per cent of F2 to F4 derived lines gave F5 derived lines that outyielded random selections by 19 to 53 per cent for one cross and 5 to 23 per cent for the second cross. These lines were 41 to 50 per cent better than the mid-parent in one cross, but were less than the mid-parent in the other cross. However, the response to selection when measured in a different year was little better than random selection. The effect of different sites also reduced the effectiveness of selection. Selection of harvest index in early generations for improvement of yield was ineffective when response was measured at the same site in the same year, or in different years. Contrary to some theoretical proposals, the same improvement in yield was obtained by selecting in early or late generations. While high yielding genotypes may be lost by delaying selection, this is counteracted by the better predictive value of late generations due to their greater homozygosity and homogeneity.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 31 (1982), S. 629-634 
    ISSN: 1573-5060
    Schlagwort(e): Triticum aestivum ; winter wheat ; vernalization ; cold treatment ; immature embryos ; excised embryos ; kinetin ; nutrient media ; seedling growth ; plant growth
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Embryo age and composition of nutrient medium affected plant growth and response to vernalization in winter wheat (Triticum aestivum L.). Root and shoot development was more in older than in younger excised embryos, and more in a medium without kinetin than in one with kinetin. Kinetin (2 mg/l) in the medium did not accelerate vernalization, probably because it tended to inhibit seedling and plant growth. Embryo age and media did not completely replace vernalization. Twenty- and 16-day-old embryos responded by flowering after 4 weeks of vernalization. Among plants raised on a standard medium from 20-day-old embryos and vernalized for 4 weeks, 84.2% flowered by or before 50 days after transplanting. Time from embryo culture to heading for 20-day-old embryos with-4-week vernalization averaged 84.6 days. Immature embryos (16–20 days old) needed only 4 weeks of vernalization compared to 6 weeks for mature embryos. Excised embryos could be vernalized as efficiently as seedlings raised by embryo culture. Embryo culture at 16–20 days after anthesis coupled with 4-week cold treatment shortens generation time of winter wheat by about 40 days.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 31 (1982), S. 965-970 
    ISSN: 1573-5060
    Schlagwort(e): Triticum aestivum ; wheat ; Puccinia graminis ; black rust ; stem rust ; aneuploids ; gene location
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Monosomic analysis of resistance to stem rust, race 11 (isolate G 425) was carried out in the cultivar Almus (GDR) possessing a 1B/1R translocation. F2 progenies of monosomic and disomic F1 plants of Almus crossed with 21 monosomic lines of Chinese Spring were tested. Two lines (1B and 6B) differed significantly from the disomic segregation ratio by a higher number of resistant plants and two other lines (1D and 6A) by a lower number of resistant plants. The results fitted a hypothesis comprising the interaction of two genes for resistance and two inhibitors.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Euphytica 31 (1982), S. 895-900 
    ISSN: 1573-5060
    Schlagwort(e): Triticum aestivum ; wheat ; male-fertility restoration ; monosomic analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary In common wheat (Triticum aestivum L.) a monosomic set of ‘Chinese Spring’ and male-sterile ‘Janus’ (with cytoplasm of T. timopheevi Zhuk.) were used to determine the chromosomal location of Rf-genes in ‘Professeur Marchal’. As revealed by test cross data, a major gene cofeerring fertility restoration was present in ‘Prof. Marchal’ on chromosome 1B. A significant deviation towards sterility was observed in some fest cross progenies. Chromosome 1B of ‘Chinese Spring’ appeared to carry a dominant restoring gene, which caused partial restoration of fertility.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 20 (1982), S. 49-57 
    ISSN: 1741-0444
    Schlagwort(e): Haemodynamics ; Modelling ; Pulsatile flow
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The purpose of this paper is to present standard results on the effect of nonlinearities on the computed pulsatile flow in a cylindrical distensible tube as a first stage in the calculation of flow in a tapered tube and blood flow in arteries. The calculations are made using the pressure-radius relationship of a rubber tube with no longitudinal motion and for a linearised relationship. The one-dimensional equations of motion are solved by the method of finite differences. The values of skin friction that are incorporated are determined from the vorticity and continuity equations for a rigid tube and a correction made to the current diameter at each time step. The accuracy of the results is assessed and the effect of varying parameters investigated. The method is applied to a segment of an infinite tube for which the linear analytical solution is available. The characteristics of the velocity wave calculated from an input pressure wave are presented as departures from the linear theory values of these characteristics, the wave speed, flux and transmission factor per wavelength. Computations are made at values of non-dimensional frequency (Stokes number α) of about 3 and 10. It is concluded that as far as physiological application is concerned (i.e. small amplitude and long wavelength) the results of linear theory are a very good first approximation for the cylindrical tube. At α=10, the relative departure of wave speed is about 0·5 times the relative diameter amplitude ( $${{\hat D} \mathord{\left/ {\vphantom {{\hat D} {\bar D}}} \right. \kern-\nulldelimiterspace} {\bar D}}$$ amplitude/mean diameter) when the pressure-radius relation is linear and the pressure and velocity waves have the same characteristics. At α=3 the corresponding wave speed departure is about 0·1 $${{\hat D} \mathord{\left/ {\vphantom {{\hat D} {\bar D}}} \right. \kern-\nulldelimiterspace} {\bar D}}$$ . The relative departure of the flux is less than 0·05 $${{\hat D} \mathord{\left/ {\vphantom {{\hat D} {\bar D}}} \right. \kern-\nulldelimiterspace} {\bar D}}$$ at α=3 and about 0·5 $${{\hat D} \mathord{\left/ {\vphantom {{\hat D} {\bar D}}} \right. \kern-\nulldelimiterspace} {\bar D}}$$ at α=10. The transmission coefficient has a relative departure of less than 0·05 $${{\hat D} \mathord{\left/ {\vphantom {{\hat D} {\bar D}}} \right. \kern-\nulldelimiterspace} {\bar D}}$$ at α=10 and its relative increase at α=3 is about 0·3 $${{\hat D} \mathord{\left/ {\vphantom {{\hat D} {\bar D}}} \right. \kern-\nulldelimiterspace} {\bar D}}$$ .
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 226 (1982), S. 589-608 
    ISSN: 1432-0878
    Schlagwort(e): Kidney (frog) ; Glomerulus ; Nephron ; Tight junctions ; Freeze-fracturing ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary By the use of thin sections and freeze-fracture replicas the glomerular and tubular structures of the kidney of the frog (Rana esculenta) were studied with special reference to intercellular junctions. In the glomerulus the filtration barrier is of very variable thickness, and frequent tight and gap junctional contacts occur between podocyte processes. Although structurally less elaborate, the proximal tubule resembles its mammalian counterpart. In the initial part the tight junctions are relatively shallow but become very broad in the mid and distal portions of the proximal tubule. The proximal tubular cells are extensively linked by gap junctions. In some animals the shapes of the cells in the proximal and distal portions of the proximal tubule were markedly different. The distal tubule consists of two segments which differ mainly in the pattern of interdigitations and the structure of the zonulae occludentes. Similarities with the tight junctional morphology of the mammalian distal tubule are striking. In the first part of the distal tubule (diluting segment) a narrow band of parallel tight junctions is found closely resembling that found in the mammalian straight distal tubule; in the more distal part of the distal tubule, however, a broad band of anastomosing tight junctional strands exists, like the zonula occludens of the mammalian convoluted distal tubule. The connecting tubule displays cellular dimorphism: its wall contains a mixture of light and dark (flask) cells. The luminal and basolateral membranes of the flask cells are covered with numerous rod-shaped particles. The tight junctions of the connecting tubule are broad and increase in depth and number of strands along its length; they are typical of a very tight epithelium. In spite of several dissimilarities with phylogenetically younger kidneys our findings suggest that many structural principles of the mammalian kidney are also represented in the kidneys of amphibians. The structural-functional relationships are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 221 (1982), S. 657-678 
    ISSN: 1432-0878
    Schlagwort(e): Stomach (Teleost) ; Endocrine cells ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the gastric mucosa of two teleost species, the perch (Perca fluviatilis) and the catfish (Ameiurus nebulosus) three endocrine cell types were found, located predominantly between the mucoid cells of the gastric mucosa. A fourth cell type is present in the gastric glands of catfish. Each cell type was defined by its characteristic secretory granules. Type-I cells were predominant in both fish. These cells contained round or oval granules with a pleomorphic core. The average diameter of granules was 400 nm for the perch and 270 nm for the catfish. Type-II cells of both species displayed small, highly osmiophilic granules about 100 nm in diameter. The secretory granules of type-III cells (260 nm in the perch and 190 nm in the catfish) were round or slightly oval in shape and were filled with a finely particulate electron-dense material. Type-IV cells of the catfish were found in the gastric glands only. Their cytoplasm was filled with homogeneous, moderately electron-dense granules averaging 340 nm in diameter. The physiological significance of these different morphological types of gastric endocrine cells requires further investigation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 222 (1982), S. 409-415 
    ISSN: 1432-0878
    Schlagwort(e): Crustacean compound eye ; Eighth retinular cell ; Crystalline tract ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The base of the crystalline tract, the distal part of the eighth retinular cell and its rhabdomer constitute a structural unit in the apical region of the retinula of Astacus fluviatilis and A. leptodactylus, shielded from the blood by a special covering cell.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 224 (1982), S. 637-645 
    ISSN: 1432-0878
    Schlagwort(e): Cell surface antigen ; Neurons ; Glia ; Electron microscopy ; Immunoperoxidase ; Monoclonal antibody
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Immuno-electron microscopy was performed on live, cultured, early postnatal cerebellar and retinal cells of the mouse to identify A2B5 antigenbearing elements. In cerebellar cultures, granule cells, some immature oligodendroglia, and astroblasts express A2B5 antigen on their cell surfaces. The typical features of astroblasts include large cisternae of the endoplasmic reticulum and a mixed population of intermediate-sized filaments and microtubules. Immature oligodendroglia cells express the antigen on their cell bodies and on procecesses filled with cytoplasm. Cytoplasm-free membranous whorls, however, are devoid of A2B5 antigen, but not of 0 or NS-1 antigens. In retinal cultures, A2B5 antigen is observed on differentiating neurons with the exception of photoreceptor cells as identified by ribbon synapses.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 224 (1982), S. 673-683 
    ISSN: 1432-0878
    Schlagwort(e): Pacinian corpuscles, rat ; Denervation ; Sensory terminals ; Nerve degeneration ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructure of Pacinian corpuscles located on the crural interosseous membrane was studied in adult rats 6 h to 10 months after transection of the right sciatic nerve. Axon terminals degenerated one day after transection and were engulfed and resorbed by cells of the inner core within one week. The axial space left after removal of the axonal debris was closed by the lamellae of the inner core. The main structural features of the inner core and capsule remained preserved after denervation throughout the period of study. The denervated inner cores, however, became atrophic 10 months after neurotomy, their mean diameter being reduced by 17.5% compared with that of contralateral control corpuscles. The number of capsular lamellae was unaltered, and perineurial pathways of the peripheral nerve stump remained preserved. Schwann cells proliferated and formed Büngner bands during the first month after denervation, but retracted their processes and became atrophic at later stages after neurotomy. Survival of Pacinian corpuscles after long-term denervation in adult rats is in contrast to their rapid degeneration within several days after nerve section in neonates.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 29
    ISSN: 1432-0878
    Schlagwort(e): Electron microscopy ; Junctions ; Smooth muscle ; Echinodermata ; Holothuria, Aspidochirotida
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Electron microscopy reveals that sarcolemmata of adjacent muscle cells form pentalaminar junctions by fusion of apposed trilaminar double leaflet membranes. These junctions appear to be candidates for low resistance pathways between muscle fibers. The muscles depolarize slowly when bathed in solutions containing elevated concentrations of KCl, and the sucrose gap method can then be used to measure the potential difference between polarized and depolarized regions. Thus the junctions which we have observed may provide the structural basis for electrical transmission through the sucrose gap.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 30
    ISSN: 1432-0878
    Schlagwort(e): Peritrophic membrane ; Tick ; Babesia ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary A peritrophic membrane (PM) has been demonstrated in the gut of feeding larvae, nymphs, and adults of the tick Ixodes dammini. This is the first report of a PM in ticks. This temporary structure divides the lumen of the gut into two compartments, an endoperitrophic space, the lumen proper, and an ectoperitrophic space located between the PM and the epithelial cells of the gut wall. The PM is a mechanical barrier and even such small particles as ribosomes derived from ingested reticulocytes are retained in the lumen proper; they are never found in the ectoperitrophic compartment. In Ixodes dammini fed on hamsters infected with Babesia microti some of the parasites are found in the ectoperitrophic space. This passage is accomplished by a highly specialized organelle, the arrowhead, which develops in some Babesia during their metamorphosis in the gut of the vector. The arrowhead, while passing through the PM, changes its fine structure and loses its internal organization as if releasing some of its contents. Its disintegration continues and it disappears shortly after the Babesia have entered the epithelial cells. Only Babesia equipped with the arrowhead structure are able to cross the PM. This is the first documented case of a parasite traversing a solidified PM.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 222 (1982), S. 25-40 
    ISSN: 1432-0878
    Schlagwort(e): Paddle cilia ; Discocilia ; Pleurobranchaea ; Chemoreceptors ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Scanning electron microscopy of various regions of the body of the marine gastropod Pleurobranchaea californica (McFarland) has revealed a characteristic cell type that bears cilia with dilated discoid-shaped tips. The tips of the cilia consist of an expansion of the ciliary membrane around a looped distal extension of the axoneme. These kinocilia have been observed in numerous other marine invertebrates and are generally referred to as paddle cilia (Tamarin et al. 1974) or discocilia (Heimler 1978). Although many functions have been proposed for paddle cilia, little empirical evidence supports any of the proposals. In Pleurobranchaea we have found that the distribution of this ciliated cell type corresponds exactly to areas of the body known from behavioral studies (Lee et al. 1974; Davis and Matera 1981) to mediate chemoreception. Transmission electron microscopy of the epithelium lining the rhinophores and tentacles of Pleurobranchaea revealed details of the ultrastructure of these ciliated cells and showed that they are primary receptors. These ciliated receptors lie in a yellow-brown pseudostratified columnar epithelium that superficially resembles the olfactory mucosa of vertebrates.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 222 (1982), S. 167-175 
    ISSN: 1432-0878
    Schlagwort(e): Pigment granules ; Chromatophores ; Granulogenesis ; Palaemonid shrimp ; Macrobrachium ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The possible biogenesis of two pigment granule types present in the monochromatic, brown chromatosomes enveloping the ventral nerve chord of the freshwater palaemonid shrimps Macrobrachium acanthurus, M. heterochirus and M. olfersii is examined by transmission electron microscopy in thin section and freeze fracture replicas. Prominent, membrane limited granules are suggested to have their origin in a complex, juxtanuclear, smooth endoplasmic reticulum labyrinth, continuous with the nuclear envelope. Amembranous, lipocarotenoid granules possibly derive from the external surface of the smooth endoplasmic reticulum. Nuclear envelope and SER membranes contain numerous 11 nm diameter intramembranous particles while pigment granule membranes exhibit fewer particles. A dictyosomal origin for the lipocarotenoid granules is discounted. Granulogenesis is suggested to be a continuous process in crustacean chromatophores.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 222 (1982), S. 261-267 
    ISSN: 1432-0878
    Schlagwort(e): Skeletal muscle ; Fiber types ; Electron microscopy ; Stereology ; Chicken
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ultrastructural and stereological assessment of the mature avian anterior latissimus dorsi (ALD) muscle showed that it contains two kinds of extrafusal fibers. This fine structural dichotomy of fiber types in the ALD correlated well with their previously reported histochemical duality. Distinct differences occur in sarcomere banding, myofibrillar area, sarcotubular and mitochondrial density, and in morphology of motor-nerve terminals. Both myofiber types in this muscle were interpreted as representing varieties of “slow” or tonic muscle fibers. Both fibers contain myofibrils that, despite differences in cross-sectional area, were large, irregular, and ribbon-shaped, typical of the “Felderstruktur” appearance of true “slow” fibers. Whereas the majority of fibers (type-1) are devoid of well-defined M-bands, the minor fiber population (type-2) exhibit prominent M-bands in the center of each sarcomere. In addition, type-1 tonic fibers contain a significantly lower mitochondrial and sarcotubular volume than the tonic fibers of type-2. While both fiber types exhibit motor-nerve terminals that are small, smooth and punctate in appearance, those on the type2 fibers often had a number of shallow postjunctional folds. Whether or not these two classes of extrafusal fiber in this muscle represent two separate and distinct types of motor units remains to be determined functionally.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 223 (1982), S. 87-99 
    ISSN: 1432-0878
    Schlagwort(e): Smooth muscle cells ; In vitro-growth ; Whole blood serum ; Plasma-derived serum ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Normal diploid cells require serum to proliferate in culture. Platelet-derived growth factor has been identified as the main serum component responsible for this effect. Here, smooth muscle cells were isolated enzymatically from the aorta of 5-day-old rats and cultured in the presence of 10% whole blood serum (WBS) or plasma-derived serum (PDS), i.e. with or without platelet factor, and studied by transmission electron microscopy. The cells proliferated actively in WBS-medium but remained quiescent in PDS-medium. Fine structurally, cells from WBS-cultures demonstrated numerous mitochondria, an extensive rough endoplasmic reticulum (RER), a large Golgi complex, a few lysosomes, and microfilaments arranged in parallel bundles. After transfer to PDS-medium, the RER- and Golgi cisternae were markedly dilated and the number of membrane-associated ribosomes decreased. Segregation of fragments of cytoplasm within autophagosomes was frequently observed and the number of lysosomes increased. Lipid droplets were more abundant and often gathered in the Golgi area. Moreover, the cells had become more irregular in shape and showed many bleb-like processes at their surface. Microfilament bundles had also become more prominent and crossed each other in different directions. These observations show that the removal of platelet factor from the medium clearly modifies the fine structure of cultured smooth muscle cells. The findings are in good agreement with the concept that platelet factor not only supports the proliferation of cultured cells but also stimulates their secretory activity.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 223 (1982), S. 267-280 
    ISSN: 1432-0878
    Schlagwort(e): Retina (Astacus) ; Rhabdom ; Osmolarity ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Alterations of the retinula cells in the retina of the light-adapted crayfish in response to hyper- and hypoosmotic van Harreveld solutions was examined by transmission electron microscopy. Increased osmolarity of the bathing medium to twice that of the physiological value leads to shrinkage of the retinula-cell somata. Microvilli, on the other hand, do not undergo shrinkage. Some other characteristic irreversible changes do, however, take place, including detachment of microvilli from the soma, showing a two- or threefold increase in diameter, and a concomitant decrease in number, probably due to fusion of microvilli. Prolonged incubation or higher osmolarities (5 isosmol) cause alteration of the microvillar membranes to whorls. Structural changes are often restricted to microvillar stacks evaginating from certain individual retinular cells. The number of affected stacks increases depending on the duration of incubation or the osmotic pressure. Hypoosmotic solution (0.5 isosmol) also induces an increase of microvillar diameters and a concomitant reduction in number of microvilli per stack. Exposure to a 20% solution of glycerol causes destruction of the rhabdom structure and the formation of whorls from microvillar membranes. The present findings suggest that the structure of the microvilli is stabilized by an axial cytoskeleton.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 224 (1982), S. 291-301 
    ISSN: 1432-0878
    Schlagwort(e): Thymus (rat) irradiation ; Electron microscopy ; Interdigitating cells ; Macrophages ; Phagocytosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Phagocytic activity and population development of medullary interdigitating cells (IDC) and cortical macrophages have been studied in the rat thymus after irradiation-induced thymocyte necrosis. IDC clearly demonstrate phagocytic activity, particularly in the 16h stage after irradiation. At this stage the number of necrotic thymocytes is maximal and the total number of phagocytic cells is insufficient to phagocytize all necrotic material. IDC increase in number slightly and are predominantly phagocytizing in the corticomedullary region (CMR), where they appear to develop from macrophage-like cells. The results indicate that medullary IDC can be phagocytic but have a different developmental pathway than cortical macrophages. Cortical macrophages greatly increase in number and acquire the appearance of tingible body macrophages by phagocytizing many necrotic thymocytes. They seem to develop from monocytes that normally enter the thymus at the CMR. During the acute involution macrophages probably also enter the cortex via the connective tissue capsule. It is suggested that thymus medullary IDC probably belong to the mononuclear phagocytes, as do the cortical macrophages. In the specific medullary environment IDC gradually develop their characteristic ultrastructure for an apparently other than phagocytic function. The similarities between IDC and epidermal Langerhans cells are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 224 (1982), S. 349-359 
    ISSN: 1432-0878
    Schlagwort(e): Ovarian follicle ; Ovulation ; Ultrastructural change ; Fowl ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary No structural changes could be observed in the stigma until 2 h before ovulation. Within a few minutes of ovulation, the stratum granulosum and theca interna disappear completely in the middle part of the stigma. By 30 min before ovulation, the rough endoplasmic reticulum in the fibroblasts of the theca externa develops conspicuously. Then a few minutes before ovulation, the theca externa becomes much thinner with a conspicuous disintegration of the collagenous fibers into individual fibrils. These structural changes may contribute to the fragility of the stigma tissue and induce rupture of the follicle.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 224 (1982), S. 383-395 
    ISSN: 1432-0878
    Schlagwort(e): Mouse ovary ; Junctions ; Freeze-fracture ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Intercellular junctions in the young mouse ovary were examined by electron microscopy utilizing freeze-fracture and thin-sectioning techniques. Projections from the granulosa cells adjacent to the oocyte (GI) traverse the zona pellucida and form small gap junctions on the oocyte surface. On the P-face of these cells, the junctional aggregations are occasionally associated with linear strands of particles. In contrast, large gap junctional areas are frequently observed between the more peripherally located granulosa cells (GE) and are also present in the theca interna (TI) cell layer surrounding the follicles. Three types of tight junctional strands are discernible on the P-face of theca externa cells (TE): angularly zigzag strands consisting of intermittently distributed intramembranous particles on wide ridges, intermediate zigzag strands consisting of more continuously distributed particles, and wavy strands consisting of rather fused particles. Tight junctional strands are also present in the middle of grooves on the E-face of endothelial cells of blood vessels. In the germinal epithelial cell layer, tight junctional strands appear to be discrete and form a less anastomosing network.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 224 (1982), S. 369-381 
    ISSN: 1432-0878
    Schlagwort(e): Pituitary gland ; Pars intermedia ; Electron microscopy ; Fetal sheep ; Lamb
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Using light and electron microscopy, the morphogenesis of the pars intermedia of the sheep pituitary gland was examined in developing lambs between 26 days of gestation and the newborn stage. Following the establishment of contact between the anterior and posterior lobe primordia seen at 26 days, the connection with the pharyngeal roof disappeared by 31 days. The lumen of Rathke's pouch, which was a prominent cavity at the earlier stages, became inconspicuous by 40 days but progressively increased in size during gestation and, in some newborn animals, contained colloid material. At 40 days, the pars intermedia consisted of a uniform population of undifferentiated cells. Cells with cytoplasmic granules were first identified at 50 days. The cytological appearance of granular cells at 70 days indicated increased synthetic activity and by 80 days they closely resembled adult glandular cells. At 100 days, membrane activity suggestive of exocytosis was first observed in granular cells; fenestrated capillaries were present, and early follicle formation between adjacent non-granular cells was seen. This apparent exocytotic release of granules was observed much more frequently between 100 days of gestation and the newborn stage than in adult pars intermedia cells. These findings indicate that glandular cells of the developing pars intermedia are actively engaged in synthesis, storage and secretion from an early stage.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 225 (1982), S. 355-364 
    ISSN: 1432-0878
    Schlagwort(e): Implantation ; Blastocyst ; Pontamine ; blue reaction ; Decidualization ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The early uterine response to transplanted, delayed and estrogenactivated blastocysts was studied ultrastructurally and compared with that induced by intrauterine instillations of deciduogenic agents (arachis oil, air). The uterine responses to delayed and activated blastocysts showed no ultrastructural or temporal differences. Already within 4 h after transfer to a sensitized uterus, the delayed blastocysts exhibited signs of activation, and both types of blastocysts had started to attach onto an undamaged epithelial lining. Signs of stromal cell differentiation into decidual cells were also seen as early as 4 h after transfer, while the Pontamine-blue reaction did not appear until after 8 h. The results therefore indicate that the transplanted blastocysts induced decidualization atraumatically and that the delayed blastocysts were either deciduogenic already before transfer or rapidly acquired deciduogenic properties after transfer. Artificial decidual induction with oil and air led to damage or death of a large number of cells in the uterine luminal epithelium. Within only 15 min after instillation pronounced signs of cell damage were seen, and later numerous cells were extruded from the epithelial lining. In the stroma ultrastructural signs of decidual cell differentiation and a Pontamine-blue reaction were observed as early as 4 h after induction. It is therefore suggested that oil and air induce decidualization via the epithelium by means of trauma.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 225 (1982), S. 443-448 
    ISSN: 1432-0878
    Schlagwort(e): Frog cerebellum ; Ependymal surface ; Cilia ; Supraependymal cells ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Ultrastructural studies of the ventricular surface of the frog cerebellum showed regional differences. In the midline region of the adult cerebellum was found a band of profusely ciliated squamous ependymal cells. In the rest of the cerebellum the ependymal cells were columnar and each had a single cilium. In the cerebellum of the premetamorphic tadpole, the squamous ependymal cells of the midline region also were monociliated. During metamorphosis they gradually became multiciliated. Additionally, supraependymal cells and synaptic elements were present on the ventricular surface of the cerebellum of adult frogs as well as in late metamorphic tadpoles. In contrast, supraependymal cells were rarely observed in premetamorphic tadpoles, and it was concluded that the supraependymal system develops during metamorphosis. It is postulated that the band of cilia may be associated with the circulation of cerebrospinal fluid, and supraependymal synaptic elements function in neuroendocrine regulation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 225 (1982), S. 663-671 
    ISSN: 1432-0878
    Schlagwort(e): Chaetognatha ; Intestine ; Pleated septate junction ; Electron microscopy ; Freeze-fracture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The intramembrane structures of the pleated septate junction which occur in the junctional complex of the intestine of the chaetognath Sagitta setosa have been investigated. The pleated septate junction is made up of linear rows of irregularly shaped and sized particles, often fused into short rods, and pits which can be fused into furrows. The distribution of these structures on E and P faces depends upon the preparative methods used. Many of the morphological characteristics are the same as those of the “lower invertebrate pleated septate junction type” defined by Green (1981a). The physiological significance of this junction is obscure. On the basis of the presence of septate junctions (both of the paired septate junction and pleated septate junction types) which have mainly morphological characteristics of the “lower invertebrate pleated septate junction” we can add to the hypothesis that chaetognaths are not related to the molluscs and arthropods.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 43
    ISSN: 1432-0878
    Schlagwort(e): Enteroendocrine cells ; Pancreatic endocrine cells ; Gastroenteropancreatic hormones ; Immunocytochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Four immunoreactive endocrine cell types can be distinguished in the pancreatic islets of B. conchonius: insulin-producing B cells, somatostatin-producing A1 (= D) cells, glucagon-producing A2 cells and pancreatic poly-peptide-producing PP cells. The principal islet of this species contains only a few PP cells, while many PP cells are present in the smaller islets. Except for the B cell all pancreatic endocrine cell types are also present in the pancreatic duct. At least six enteroendocrine cell types are present in the gut of B. conchonius: 1. a cell type (I) with small secretory granules, present throughout the intestine, and possibly involved in the regulation of gut motility; 2. a C-terminal gastrin immunoreactive cell, probably producing a caerulein-like peptide; these cells are located at the upper parts of the folds, especially in the proximal part of the intestinal bulb; 3. a met-enkephalin-immunoreactive cell, present throughout the first segment; 4. a glucagon-immunoreactive cell, which is rare in the first segment; 5. a PP-immunoreactive cell, mainly present in the first half of the first segment; 6. an immunoreactive cell, which cannot at present be specified, located in the intestinal bulb. The latter four cell types are mostly located in the basal parts of the folds, although some PP-immunoreactive cells can also be found in the upper parts. Most if not all enteroendocrine cells are of the open type. The possible functions of all enteroendocrine cell types are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 44
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 226 (1982), S. 327-335 
    ISSN: 1432-0878
    Schlagwort(e): Xenopus ; Spleen ; B-lymphocyte ; Immunofluorescence ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary An indirect immunofluorescence study of the frozen sections of the spleen of an anuran amphibian, Xenopus laevis, showed that lymphocytes bearing a small amount of immunoglobulin (Ig) were localized mostly in the white pulp of non-immunized toads. There were fewer fluorescent cells in the red pulp. In the toads hyperimmunized with human gamma globulin (HGG), cells with strong cytoplasmic fluorescence increased significantly in the outer part of the white pulp. Electron microscopy of spleens from these toads showed that plasma cells at different stages of maturation were abundant in the white pulp, whereas in the red pulp, a smaller number of maturer plasma cells were observed. These results indicate that, in contrast with its mammalian counterpart, the splenic white pulp of this anuran is the site where thymusin-dependent lymphocytes commence blast formation and transformation into plasma cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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