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  • 1
    Electronic Resource
    Electronic Resource
    A light- and electron-microscopic investigation of gametogenesis in Typosyllis pulchra (Berkeley and Berkeley) (Polychaeta: Syllidae) (1981)
    Springer
    Cell & tissue research 218 (1981), S. 641-658 
    Details
    ISSN: 1432-0878
    Keywords: Gametogenesis polychaete ; Oogenesis ; Peritoneum ; Nurse cell ; Vitellogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Oogenesis in Typosyllis pulchra begins with a short proliferative gonial phase. Gonial clusters, consisting of six to eight syncytial sibling cells, are surrounded by gonial peritoneum and are eventually liberated into the coelom. At about the same time as the onset of the coelomic phase, one gonial cell in each cluster differentiates, begins to accumulate yolk and increases in size, eventually to become a mature oocyte. Yolk is composed of lipid droplets and membranebound protein granules. The protein component appears to be at least partially synthesized by the oocyte although there are some signs of endocytosis. Nurse cells and peritoneal cells are apparently able to manufacture some protein that may also be utilized by the oocyte. The nurse cells maintain cytoplasmic continuity with the oocyte, and mitochondria and ribosomes are often seen within the intercellular bridges between oocyte and nurse cell. Immediately prior to spawning, oocytes undergo prematuration and cytoplasmic reorganization. Ultrastructural changes which occur during oocyte growth and maturation are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00210121
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  • 2
    Electronic Resource
    Electronic Resource
    A light- and electron-microscopic investigation of gametogenesis in Typosyllis pulchra (Berkeley and Berkeley) (polychaeta: Syllidae) (1981)
    Springer
    Cell & tissue research 218 (1981), S. 623-639 
    Details
    ISSN: 1432-0878
    Keywords: Gametogenesis polychaete ; Stolonization ; Gonad ; Gonial cell ; Spermiogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Typosyllis pulchra reproduces by the production of three to four gamete-bearing stolons (schizogamy) during consecutive 30-day periods. Although gonads are found in a large number of segments, only those in the posterior-most segments produce gametes and become incorporated into the developing stolon. The more anterior gonads remain undifferentiated and probably sexually undetermined until they are needed in future stolonizations. Gonial cells, which will eventually become either male or female, are ultrastructurally identical at the onset of each stolonization period. Spermatogenesis is marked by a short proliferative period followed by differentiation and spermiogenesis. The first ultrastructural signs of spermatogenesis were found in coelomic spermatogonia on day 10 of stolon formation. Spermatogonia are joined by intercellular bridges, which are maintained until the early spermatid stage. Synaptonemal complexes mark the onset of meiosis, which is apparently synchronized in the syncytial clusters of primary spermatocytes. Spermiogenesis occurs during the final 10 days of stolonization and a variety of stages is present within a single animal. All sperm mature by the time the stolon detaches. Acrosome formation and nuclear condensation are described in addition to the ultrastructure of mature sperm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00210120
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of nonionizing radiation on the purkinje cells of the uvula in squirrel monkey cerebellum (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 2 (1981), S. 241-246 
    Details
    ISSN: 0197-8462
    Keywords: monkey cerebellum ; Purkinje cells ; nonionizing radiation ; microwaves ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Pregnant squirrel monkeys were exposed to 2450-MHz (CW) microwaves at an equivalent power density of 10 mW/cm2 (SAR 3.4 mW/g) for three hours daily in a cavity-cage module. The exposure began when pregnancy was determined by a hormonal method, and continued through the offspring's first 9.5 months. After irradiation, the brains of the offspring were fixed with formaldehyde, and the inferior vermis of each cerebella was removed and processed for histologic observations. Purkinje cell density in the uvula was determined in sagittal serial sections. There was no significant difference between control and experimental animals in the number of Purkinje cells per mm of Purkinje cell line (linear density), as well as in the density of Purkinje cells in the Purkinje cell layer.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250020305
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of nonionizing radiation on the purkinje cells of the rat cerebellum (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 2 (1981), S. 247-257 
    Details
    ISSN: 0197-8462
    Keywords: nervous system ; rat cerebellum ; nonionizing radiation ; Purkinje cells ; microwaves ; radiofrequency ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: In one experiment, Sprague Dawley rats (16-21 days of gestation) and their offspring were exposed to 100-MHz (CW) electromagnetic radiation at 46 mW/cm2 (SAR 2.77 mW/g) for 4 h/day for 97 days. In another experiment, the pregnant rats were irradiated daily from 17 to 21 days of gestation with 2450-MHz (CW) microwaves at 10 mW/cm2 (SAR 2 mW/g) for 21 h/day. In a third experiment, 6-day-old rat pups were irradiated 7 h/day for five days with 2450-MHz radiation at 10 mW/cm2. Equal numbers of animals were sham irradiated in each group. Quantitative studies of Purkinje cells showed a significant and irreversible decrease in rats irradiated during fetal or fetal and early postnatal life. In animals exposed postnatally, and euthanized immediately after irradiation, significant decrease in the relative number of Purkinje cells was apparent. However, restoration apparently occurred after forty days of recovery.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250020306
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