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  • 1
    Electronic Resource
    Electronic Resource
    The structure of the chromosomes in human primordial oocytes (1967)
    Springer
    Chromosoma 22 (1967), S. 358-377 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Primordial oocytes (oocytes in primordial follicles) from human ovaries aged 51/2 months post conception to 11 3/4 years post partum were examined in: (a) squash preparations of fresh and fixed tissue; (b) histological preparations; and (c) thin sections by electron microscopy, in order to study the structure of the chromosomes. — The light microscope shows that the chromosome consists of a thread bearing numerous fine lateral appendages. Cytochemical tests indicate that the thread contains DNA, and is surrounded by material containing RNA and protein. — The electron microscope shows that there are three main structural components in the chromosome: (i) an axis or “core” containing at least two longitudinal strands about 200 Å thick; (ii) a surrounding sheath composed of coiled fibrils which form symmetrically arranged columns and loops, and (iii) clusters of large granules which are associated with the outer parts of the sheath. Small nucleoli and other granular bodies are also present. — These observations indicate the presence of lampbrush chromosomes in the human oocyte. The significance of this type of chromosome in mammals is discussed in relation to the differential radiosensitivity of the oocytes, and to the form of chromosomes at the dictyate stage in rodents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319880
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  • 2
    Electronic Resource
    Electronic Resource
    Radiosensitivity of Oogonia and Oocytes in the Foetal and Neonatal Monkey (1967)
    [s.l.] : Nature Publishing Group
    Nature 214 (1967), S. 981-983 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Germ cells in developing female monkeys are considerably more resistant to radiation-induced cell death than those at equivalent stages of gametogenesis in rats and ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/214981a0
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  • 3
    Electronic Resource
    Electronic Resource
    Organ culture of the rat thyroid gland (1973)
    Springer
    Cellular and molecular life sciences 29 (1973), S. 1548-1550 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Die Ultrastruktur der Rattenschilddrüse wird bis zu 8 Tagen in Organkulturen erhalten, was für radioautografische Studien der Ultrastruktur vorteilhaft ist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01943911
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  • 4
    Electronic Resource
    Electronic Resource
    Dissociation of response to injected gonadotropin between the Graafian follicle and oocyte in pigs (1976)
    [s.l.] : Nature Publishing Group
    Nature 260 (1976), S. 156-158 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Mature Large White gilts with 20- or 21-d oestrous cycles were assigned to one of four groups and given a single intramuscular injection of 500 or 1,000 IU of HCG (Organon) in saline on day 17, 18, 19 or 20 of the cycle. Ovulation occurs 40?42 h after such an injection given during prooestrus8,9. ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/260156a0
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  • 5
    Electronic Resource
    Electronic Resource
    The effects of X-irradiation on mammalian oocytes in organ culture (1969)
    Springer
    Radiation and environmental biophysics 6 (1969), S. 39-45 
    Details
    ISSN: 1432-2099
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Summary A technique for maintaining mammalian ovaries in organ culture is described. Ovaries of rats, mice, monkeys and humans have been maintained in a histologically normal condition for up to 20 days in culture, during which many were X-irradiated. The doses of X-rays required to destroy all the primordial oocytes in organ cultures are similar to those reported forin vivo studies. The human foetal ovary is resistant to X-irradiation. Some oocytes survive for 7 days following exposure to 4000 R in organ culture. The radiation sensitivity of the human ovary is discussed: it would appear that it is amongst the most resistant to oocyte-killing known.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01403867
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  • 6
    Electronic Resource
    Electronic Resource
    Studies on the maintenance of porcine graafian follicles in organ culture (1975)
    Springer
    Cellular and molecular life sciences 31 (1975), S. 133-135 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Résumé Nous avons étudié les follicules de Graaf dans différents milieux de culture organique classique, le but éventuel étant de voir comment le LH provoque la reprise de la méiose. Les follicules ont été prélevés de l'ovaire de 16 truies se trouvant à différents stades du cycle oestrien et mis en culture sous pression augmentée (0.703 kg/cm2). En général, les couches de cellules et même l'ovocyte supportèrent bien la mode de culture décrit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01924721
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  • 7
    Electronic Resource
    Electronic Resource
    Fluxes of elements in rain passing through forest canopies in south-eastern Australia (1987)
    Springer
    Biogeochemistry 4 (1987), S. 27-39 
    Details
    ISSN: 1573-515X
    Keywords: canopy interception ; elemental fluxes ; Eucalyptus ; leaching ; Pinus radiata ; precipitation chemistry ; throughfall ; stemflow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The elemental content of rainfall (bulk deposition), throughfall and stemflow was measured inPinus radiata D. Don andEucalyptus forests in Gippsland, Victoria. Accessions in rainfall (mg m−2 year−1) averaged: organic-C 551, NO3 −-N 96, NH4 +-N 62, total-N 303, K+ 382, Na+ 2250, Ca2+ 1170, and Mg2+ 678. The mean pH of rainfall was 5.9. Concentrations of all elements were greater in throughfall than in rainfall, and generally greater in stemflow than in throughfall. However, pH of pine throughfall was higher than that of rainfall, and pH of eucalypt throughfall was lower than that of rainfall. There was a net efflux of inorganic-N from pine crowns to rainfall, whilst in eucalypts there was generally net sorption of inorganic-N from rainfall. In both species organic-N was leached from the crowns and the net efflux of total-N from eucalypt crowns (50 mg m−2 year−1) averaged one-quarter of that in pines. Increases in the organic-C content of throughfall relative to rainfall in eucalypts were two to four times those in pines. Increases in the content of other elements in throughfall were comparable in pines and eucalypts and within the ranges K+ 615–1360, Na+ 480–-1840, Ca2+ 123–780 and Mg2+ 253–993 mg m−2 year−1. However, enrichment of Ca2+ may have been due to dust trapped in the canopies. Stemflow contributed significantly to the total amounts of elements reaching the forest floor in water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02187360
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  • 8
    Electronic Resource
    Electronic Resource
    Accession and cycling of elements in a coastal stand ofPinus radiata D. Don in New Zealand (1985)
    Springer
    Plant and soil 86 (1985), S. 303-307 
    Details
    ISSN: 1573-5036
    Keywords: Aerosols ; Bulk precipitation ; Coastal ; Cycling ; Elements ; Filtering ; Leaching ; Literfall ; Nutrients ; Pinus radiata ; Throughfall
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The accession and cycling of elements in a 14-year-old coastal stand ofPinus radiata D. Don was measured for one year. The element contents (mg m−2 year−1) of bulk precipitation and throughfall respectively were: NO3−N 41, 12; NH4−N 133, 154; organic-N 157, 396; Na 4420, 9700; K 387, 2900; Ca 351, 701; Mg 486, 1320. Of the increase in element content of rainwater beneath the forest canopy 20% (NH4−N), 70% (organic-N), 3% (Na), 90% (K), 20% (Ca) and 30% (Mg) was attributed to leaching; the remainder to washing of aerosols filtered from the atmosphere by the vegetation. The canopy absorbed approximately 40 mg m−2 year−1 of NO3−N. Litterfall was the major pathway for the above-ground biogeochemical cycle of N (93%), Ca (96%) and Mg (74%), and leaching was the major (73%) pathway for K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02182910
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  • 9
    Electronic Resource
    Electronic Resource
    The origin of cytoplasmic inclusions from the nuclear envelope of mammalian oocytes (1968)
    Springer
    Cell & tissue research 93 (1968), S. 45-55 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Oocytes in foetal and neonatal human, monkey and cow ovaries have been examined by electron microscopy. Dilatations of varying size and form are present between the two nuclear membranes in cells from the pre-leptotene stage to the early diplotene stage of meiosis. In the early part of this period the dilatations are limited in size and appear empty. At pachytene and early diplotene they are more complex and contain membrane-bound inclusions of two types: groups of small irregular profiles, or round to oval bodies which contain material at times resembling nuclear chromatin. The possible significance of these structures in relation to the early growth and differentiation of the cytoplasm of the oocyte is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325022
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  • 10
    Electronic Resource
    Electronic Resource
    Electron microscope studies of radiation-induced degeneration in oocytes of the sexually mature rhesus monkey (1972)
    Springer
    Cell & tissue research 133 (1972), S. 435-454 
    Details
    ISSN: 1432-0878
    Keywords: Oocytes ; Monkey ; Radiation damage ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This study describes the effects of acute X-irradiation of the ovaries upon the structure of primordial follicles in mature rhesus monkeys. Doses of 1000 r to 12000 r, and post-irradiation intervals of 7 hours to 30 days were used. Oocytes in biopsies from irradiated ovaries were compared with those removed from the same ovaries prior to treatment or from contra-lateral controls. The results of the treatment were assessed using light and electron microscopy. The fine structural features of normal primordial oocytes are described, with particular reference to mitochondria and dense granular bodies. Some observations on spontaneous degenerative changes are included. Irradiated ovaries are classified into four arbitrary groups according to the severity of cellular damage visible in primordial follicles with the light microscope. Effects are more marked following higher doses and/or longer intervals; the most obvious changes are pyknosis of nuclei and accumulation of dense granules in the follicle cell cytoplasm. Early changes in oocytes are relatively difficult to detect, but lead to clumping of cytoplasmic and nuclear contents at more advanced stages of degeneration. Alterations in oocyte fine structure consist mainly in swelling and disruption of membrane-bound organelles, and condensation of nuclear and nucleolar chromatin. They thus resemble those occurring during spontaneous atresia, although the damage to follicle cells is evident much sooner after irradiation. These findings are compared with those made for species in which primordial follicles are known to be destroyed by much lower doses of X-rays than were used here. The contribution to the radiation-response made by the relative radiosensitivities of oocytes and follicle cells in different species is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307127
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