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  • 1
    Electronic Resource
    Electronic Resource
    SEM observations on polar body elimination and changes of the oocyte surface during egg maturation in the newt Triturus alpestris (Amphibia, Urodela) (1991)
    Springer
    Development genes and evolution 200 (1991), S. 156-161 
    Details
    ISSN: 1432-041X
    Keywords: SEM observation ; Newt eggs ; Oocyte surface ; Maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have studied the surface of the animal half of ovulated newt eggs recovered from different portions of the oviduct. The germinative area, about 40 μm diameter, is localized in the region of the whitish polar spot, about 450 μm diameter. The structural changes in the germinative area are connected with the formation and extrusion of the first and second polar bodies. Of the two types of oviductal eggs observed, those covered with microvilli (type 1) were found only in the ostial portions of the oviduct, whilst those covered with microfolds (type 11) were found more distally. The structural difference between these two types may be related to the known reduction in surface area of the cell membrane during oocyte maturation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00190235
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  • 2
    Electronic Resource
    Electronic Resource
    Variability of Actinocyclus kuetzingii (A.S.) Sim. in the Littorina sediments of the Polish Baltic Coast (1983)
    Springer
    Hydrobiologia 103 (1983), S. 251-256 
    Details
    ISSN: 1573-5117
    Keywords: paleolimnology ; diatom flora ; sediments ; Vistula Lagoon ; Poland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The variability of Actinocyclus kuetzingii (A.S.) Sim. in the Littorina deposits of the Vistula Lagoon and Lake Druzno were studied. During the time of the Littorina Lake Druzno was a part of the Vistula Lagoon. In the different parts of the Lagoon both the abundance of A. kuetzingii and the diameter of its valves change in a manner associated with phases of the Littorina transgression. Coscinodiscus (Actinocyclus) kuetzingii fo. subsalsa Brockmann is probably an ecotype of A. kuetzingii (A.S.) Sim.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00028461
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  • 3
    Electronic Resource
    Electronic Resource
    Histochemistry and isomyosins of tail musculature inXenopus (1989)
    Springer
    Journal of muscle research and cell motility 10 (1989), S. 290-296 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The main bulk of the larval tail inXenopus laevis is composed of thick muscle fibres which are succinate dehydrogenase (SDH) negative and show strong positive ATPase activity only at alkaline preincubation (pH 10.4). The thin muscle fibres (which cover the surface of the myotomes and extend to the tail tip) show positive SDH activity as well as strong positive ATPase activity after both alkaline and acid preincubations (pH 10.4, 4.5, 4.4, and 4.3). The pattern of myosin isoenzymes does not change in the tail muscle in the course of development ofXenopus: the same three bands of larval isomyosins were found in all the examined developmental stages: 40, 47, 50 and 56. However, the larval bands were distinct from three bands of myosin isoforms in the musculus longissimus dorsi (MLD) and musculus grastrocnemius (MG) of the metamorphosedXenopus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01758425
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  • 4
    Electronic Resource
    Electronic Resource
    Yolk-platelet crystals in three ancient bony fishes: Polypterus bichir (polypteri), Amia calva L., and Lepisosteus osseus (L.) (Holostei) (1982)
    Springer
    Cell & tissue research 222 (1982), S. 159-165 
    Details
    ISSN: 1432-0878
    Keywords: Oocyte ; Yolk platelet ; Lipoprotein ; Crystal ; Fishes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Yolk-platelet crystals in Amia calva L., Lepisosteus osseus (L.) and Polypterus bichir have orthorhombic features with unit-cell dimensions a= 8.3...8.8 nm, b= 16.4...16.9 nm and c= 18.6...19.8 nm as determined in electron-diffraction patterns of fixed, epoxy-resin embedded and thinsectioned material. Electron-diffraction patterns, crystal projections and the above unit-cell data make them extremely similar to the orthorhombic yolkplatelet crystals known for amphibians and teleosts. This observation fills a gap in yolk-platelet research and supports the view that the general architecture of yolk platelets has been conserved for nearly 400 million years. It follows that the peculiar platelet architecture itself has physiological significance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218296
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  • 5
    Electronic Resource
    Electronic Resource
    Organization and fine structure of extraocular muscles in Carassius and Rana (1969)
    Springer
    Cell & tissue research 94 (1969), S. 194-204 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Two types of muscle fibers, red (-slow) and white (-twitch), have been described in the extraocular muscles of Carassius and Rana, respectively. 2. Red and white muscle fibers occupy a definite position in particular eye muscles and occur in almost constant numerical relation. 3. The red fibers in the fish extraocular muscles are supposedly slow. The position of the triads is at the level of the A/I junction, whereas that of the white muscle fibers is at the Z line level. 4. In the frog the extraocular muscles consist of two types of muscle fibers, which have morphological features of slow and fast fibers, respectively, the triads being localized at the Z line level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00339356
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  • 6
    Electronic Resource
    Electronic Resource
    Cytomorphometry of sarcoplasmic reticulum in extrinsic eye muscles of the teleost (Tinca tinca L.) (1973)
    Springer
    Cell & tissue research 136 (1973), S. 535-544 
    Details
    ISSN: 1432-0878
    Keywords: Muscle fibers ; Eye muscles (teleost) ; Sarcoplasmic reticulum ; Differences of organization ; Cytomorphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The sarcoplasmic reticulum of the white and red muscle fibers in the extrinsic eye muscle of the tench (Tinca tinca L.) differs in its organization. The SR of the white fibers is organized according to the Z type, the SR of the red fibers according to the A/I type. In order to estimate the volume and surface of the SR component in both types of muscle fibers, a stereological analysis was carried out. The volume of the SR expressed as a volume density (Vv SR) is twofold greater in the white than in the red muscle fibers. The surface of the SR, expressed as surface density (Sv SR) is 20,5% larger in the white muscle fibers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307369
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  • 7
    Electronic Resource
    Electronic Resource
    The fine structure of striated muscle fibres of tunica muscularis of the intestine in some teleosts (1971)
    Springer
    Cell & tissue research 113 (1971), S. 472-489 
    Details
    ISSN: 1432-0878
    Keywords: Striated musculature ; Intestine-Teleosts ; Types of fibres ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The muscular layer of the fish oesophagus is made up exclusively of striated muscles, which form a circular and a longitudinal layer. The intestinal muscular layer of the tench, which is an exception among the vertebrates in this respect, consists of two layers of striated muscles and a layer of smooth ones. The organization of striated muscle fibres is described from the muscular layer of the alimentary canal in four species: the tench, crucian carp, gudgeon and stone-loach. The fibres of the oesophagus differ from each other in diameter, length of sarcomeres, glycogen content and, in the case of one species, organization of SR. On the basis of the organization of sarcomeres all the fibres examined must be counted among the slow-contracting ones (broad Z line). The sarcoplasmic reticulum is organized according to the Z type except for the fibres of the oesophageal muscles in which the SR represents the A-I type. Two types, “en grappe” and “en plaque”, of nerve endings have been observed. The presence of relatively large dense core vesicles seems to indicate their adrenergic origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325667
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  • 8
    Electronic Resource
    Electronic Resource
    Immunohistochemical analysis of connexins 26, 32 and 43 in rat uterus during late pregnancy: lack of connexin 26 in the myometrium (1998)
    Springer
    Journal of molecular histology 30 (1998), S. 307-316 
    Details
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The spatial and temporal patterns of expression of connexin 26, connexin 32 and connexin 43 were investigated in rat uterus at days 17, 19 and 22 of pregnancy and during delivery (23 days) by immunocytochemistry, Gap junctions, which are essential for the development of labour, are known to undergo rapid increase in the rat myometrium at the end of pregnancy. The expression of connexin 43, the major myometrial gap junction protein, was low throughout pregnancy but increased immediately before the onset of labour (day 22). It was found predominantly in the myometrium, although limited staining was also apparent in the stroma. Immunolabelling revealed the presence of connexins 26 and 32 in uterine luminal epithelial cells on days 17 and 19 of pregnancy, with a marked increase in connexin 26 expression at days 19, 22 and 23; however, marked expression of connexin 32 was apparent only at day 23. No immunoreactivity for either connexin 26 or 32 was found in myometrial cells at any stage of pregnancy. We conclude, contrary to other recent reports, that connexin 26 is not a gap junction protein of the rat myometrial smooth muscle cell. © 1998 Chapman & Hall
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003224225975
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  • 9
    Electronic Resource
    Electronic Resource
    The fine structure of striated muscles in teleosts (1967)
    Springer
    Cell & tissue research 79 (1967), S. 562-580 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The organization of skeletal and cardiac muscles of fishes described on the basis of observations carried out on several species of freshwater fishes (Tinca tinca, Misgurnus fossilis, Perca fluviatilis, Lebistes reticidatus) and marine fishes (Gobius minutus, Pleuronectes platessa, Ammodytes tobianus). Truncal, subcutaneous, extrinsic eye and cardiac muscles were used for study. Glutaraldehyde-fixed tissue was refixed in OsO4, embedded in Epon and after polymerization, cut into ultra thin sections and examined by an electron microscope. White and red muscles were distinguished in the material examined. The latter was represented by subcutaneous muscles and small fibres of extrinsic eye muscles. Particular types of fibers differ from each other in their organization of the SR and localization of the T system tubules. In the most muscles the T system tubules are situated at the level of the Z line. In the small fibers of extrinsic eye muscles alone these tubules lie at the A-I junction. The myocardiac cells consist of a cylindrically shaped myofibril. In the middle of the cylinder is the nucleus, the remaining space being filled with numerous mitochondria. A loose sarcoplasmic network is twined around the myofibril.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336313
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