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  • 1
    Electronic Resource
    Electronic Resource
    Microdissection studies of the dividing neuroblast of the grasshopper, chortophaga viridifasciata (De Geer) (1953)
    Springer
    Chromosoma 5 (1953), S. 199-220 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Microdissection studies of the dividing neuroblast of the grasshopper,Chortophaga viridifasciata, lead to the following conclusions: 1. The spindle at metaphase is a semisolid body situated in a fluid cytoplasm; it consists largely of longitudinally oriented components; it appears to be attached at its poles to the adjacent region of the plasma membrane by weak astral fibers. From prometaphase through early anaphase the chromosomes are securely attached to the spindle at their centromeres. The spindle develops during prometaphase from the fluid karyolymph; during anaphase it undergoes liquefaction, which begins in the equatorial region and spreads poleward with or slightly in advance of the chromosome centromeres. By late anaphase the chromosomes at each pole are held firmly in a circle at their proximal ends. 2. The interzonal region of the anaphase cell consists of fluid protoplasm traversed by fine, invisible interzonal connections joining the distal ends of sister chromosomes. Its elongation during anaphase is an intrinsic process that is independent of any attachment of the spindle to the adjacent cell membrane by astral rays and appears to be responsible for much of the anaphase separation of sister chromatids. 3. Early anaphase separation of sister chromatids begins at the centromere and progresses distally. 4. Polarization of the neuroblast is largely independent of the spindle and chromosomes. 5. Formation of the cleavage furrow is independent of the spindle and chromosomes, but its position depends to a limited extent on their position at late anaphase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01271487
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  • 2
    Electronic Resource
    Electronic Resource
    Anaphase chromosome movement in the unequally dividing grasshopper neuroblast and its relation to anaphases of other cells (1977)
    Springer
    Chromosoma 64 (1977), S. 191-206 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The positions of the two sets of chromosome kinetochores, the spindle poles, cell membrane adjacent to the poles, and cleavage furrow of grasshopper neuroblasts in culture at 38°C were determined at short-time intervals during anaphase. The percent of motion due to poleward movement and spindle elongation, which coincide in time, were calculated for each minute, the former falling from 61% in the first minute to 15% in the seventh minute, and increasing to 86% in the final minute, probably as a result of pressure and bending of the spindle. Of the total chromosome movement during anaphase 44.6% is due to poleward movement of the daughter kinetochores and 55.4% to spindle elongation. The maximum velocity of a set of kinetochores is 3.41 μm/min and the mean velocity 1.86 μm/min (one-half the rate of separation). Various studies of anaphase chromosome movement in different cells and different species suggest certain generalizations, some of which are based on very small samples and so must be considered quite tentative: (1) The combination of poleward movement and spindle elongation is much more frequent than either acting alone. (2) These components of movement may coincide in time, overlap, or spindle elongation may follow poleward movement, but spindle elongation never begins before poleward chromosome movement. (3) There is an optimum temperature for the rate of chromosome movement, above and below which the rate gradually decreases. (4) In homoiothermic animals this optimum occurs at normal body temperature. (5) In homoiothermic animals the velocity falls more rapidly with a decrease in temperature than in poikilothermic animals. (6) Animals with large chromosomes (amphibia, grasshoppers) have higher chromosome velocities than those with small chromosomes. (7) Non-meiotic cells and secondary spermatocytes have higher velocities than primary spermatocytes of the same species. (8) Chromosome velocity is lower in malignant than non-malignant cells. (9) Chromosome velocity tends to be positively correlated with the distance the chromosomes travel during anaphase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328077
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  • 3
    Electronic Resource
    Electronic Resource
    THE GRASSHOPPER NEUROBLAST CULTURE TECHNIQUE AND ITS VALUE IN RADIOBIOLOGICAL STUDIES (1961)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 95 (1961), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1961.tb50088.x
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  • 4
    Electronic Resource
    Electronic Resource
    Intensity effects of ultraviolet radiation of wavelength 2537 A on mitosis in the grasshopper neuroblast (1945)
    Philadelphia : Wiley-Blackwell
    Journal of Cellular and Comparative Physiology 26 (1945), S. 165-173 
    Details
    ISSN: 0095-9898
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1030260304
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  • 5
    Electronic Resource
    Electronic Resource
    Mitotic effects of ultraviolet radiation of the 2250 Å region, with special reference to the spindle and cleavage (1948)
    Philadelphia : Wiley-Blackwell
    Journal of Cellular and Comparative Physiology 31 (1948), S. 149-173 
    Details
    ISSN: 0095-9898
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1030310205
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  • 6
    Electronic Resource
    Electronic Resource
    Immediate effects of low doses of ultraviolet radiation of wavelength 2537 a on mitosis in the grasshopper neuroblast (1944)
    Philadelphia : Wiley-Blackwell
    Journal of Cellular and Comparative Physiology 23 (1944), S. 157-169 
    Details
    ISSN: 0095-9898
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1030230304
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  • 7
    Electronic Resource
    Electronic Resource
    Immediate effects of 250 R of X-rays on the different stages of mitosis in neuroblasts of the grasshopper, Chortophaga viridifasciata (1940)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 66 (1940), S. 11-23 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1050660104
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  • 8
    Electronic Resource
    Electronic Resource
    Immediate effects of 31 r of x-rays on the different stages of mitosis in neuroblasts of Chortophaga (1942)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 71 (1942), S. 449-462 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1050710303
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  • 9
    Electronic Resource
    Electronic Resource
    The intergeneric homology of an atypical euchromosome in several closely related Acridinae (order orthoptera) (1936)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 59 (1936), S. 123-161 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An atypical euchromosome, characterized by the large size and deep stainability of its chromomeres during the meiotic prophase, occurs in representatives of seven genera of Acridinae, viz., Chorthippus curtipennis, Euchorthippus pulvinatus, Stenobothrus lineatus, Omocestus ventralis, Stauroderus biguttulus, Gomphocerus rufus, and Aeropedellus clavatus. This element, which is termed the ‘megameric chromosome,’ stains more deeply than the other euchromosomes also during interkinesis and early spermiogenesis. The megameric chromosomes of the individual exhibit striking similarity in the number, size, and arrangement of their chromomeres through successive stages of the meiotic prophase. All the evidence from cytological study indicates that these chromosomes are intergenerically homologous. This is chiefly significant in the support it gives to the theory of chromosome individuality. The heteromorphic megameric tetrad of one individual of S. biguttulus - unequal because of a deficiency - usually undergoes segregation in the second division. The megameric chromosomes display splits previous to synapsis. Pairing begins at their proximal ends and proceeds distally. All the euchromosomes of the spermatid nucleus show splits in preparation for the first cleavage division of the zygote.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1050590107
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  • 10
    Electronic Resource
    Electronic Resource
    Intercellular bridges and factors determining their patterns in the grasshopper testis (1988)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 196 (1988), S. 173-185 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Intercellular bridges joining cells contained in cysts of Chortophaga viridifasciata testes were studied with light and electron microscopy. Preparations consisted of expressed whole cells (living, or fixed and stained) as well as sections. The secondary spermatogonia of each cyst are joined centrally by persisting fused interzonal bodies (fusomes) of incompletely cleaved cells. Shifts in cell orientation during anaphase are apparently responsible for central as opposed to chain linkage of cells. In the primary spermatocytes, the central fusome is replaced by a chain linkage, apparently resulting from the breakdown of the fusome into its original interzonal body components. Intercellular bridges are also present in spermatids, but there is no evidence to indicate the time of their formation (in the immediately preceding meiotic divisions or in the secondary spermatogonial divisions). The function of the compact centrally situated fusome in the secondary spermatogonial cyst is discussed as it relates to synchrony, number of cell divisions, spermatodesm formation, and fertility.
    Additional Material: 40 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051960206
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