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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 115 (1971), S. 165-183 
    ISSN: 1432-0878
    Keywords: Rotifer ; Ovary ; Oogenesis ; Reproduction ; Fine Structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The reproductive systems of mictic and amictic females of the rotifer, Asplanchna, were examined in the electron microscope. No significant anatomical differences could be detected. The ovary consists of a syncytial vitellarium, a germarium containing primary oocytes, and a syncytial follicular layer surrounding the oocytes and joined to them and to the vitellarium. The entire structure is surrounded by an oviduct which expands distally to form a “uterus” and becomes continuous with the integument at the urogenital pore. The oviduct has three morphologically distinct regions and does not appear to be syncytial. All oocytes are joined by cytoplasmic bridges to the vitellarium, but are not connected to each other. Cortical granules arise in the vitellarium and are subsequently transported to growing oocytes through the bridges. The chromosomes of young amictic oocytes are highly condensed while those of mictic oocytes are more diffuse before the onset of growth. The nuclear envelope is quite regular in amictic oocytes, whereas it is highly convoluted in oocytes of mictic females. Nucleolar extrusions are abundant in the perinuclear cytoplasm of the vitellarium and young oocytes. These extrusions incorporate 3H-uridine and 3H-leucine; it is suggested that they function in ribosome biosynthesis.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 115 (1971), S. 184-195 
    ISSN: 1432-0878
    Keywords: Oogenesis ; Rotifer ; RNA synthesis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Oocyte development in Asplanchna brightwelli was studied by observation through the transparent body wall of living females and by electron microscopy. During oogenesis, which requires four to six hours, the oocyte increases in volume approximately 1000-fold. Most of its cytoplasm appears to be derived from the vitellarium by direct flow through the cytoplasmic bridge. This flow is rapid enough to be easily observed in the living female at low magnifications. Ribosomes, mitochondria, cortical granules, and lipid droplets were observed in the bridge area in electron micrographs. RNA synthesis during oogenesis was studied by means of autoradiography. Very little synthesis could be demonstrated in oocyte nuclei at any period of oogenesis, whereas the vitellarium nuclei show active incorporation of 3H-uridine throughout the reproductive life of the adult female. Most of this RNA is subsequently transferred to developing oocytes.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 187 (1977), S. 219-240 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The differentiation of leukocytes in the bone marrow and blood of normal adult male rats was studied by electron microscopy and peroxidase cytochemistry. Tissue samples were fixed in glutaraldehyde, or paraformaldehyde-glutaraldehyde, and incubated in a peroxidase medium containing 3,3′-diaminobenzidine and H2O2 at pH 7.6. Mature cells of blood were identified, and then the earlier stages of maturation in bone marrow were analyzed. In immature cells of four cell lines, neutrophils, monocytes, basophils, and eosinophils, peroxidase is synthesized and could be demonstrated in the rough endoplasmic reticulum (RER), Golgi complex, and in cytoplasmic granules. Later in maturation, reaction product for peroxidase could not be found in RER or Golgi complex, indicating that peroxidase synthesis had ceased. In two cell lines, neutrophils and monocytes, peroxidase-negative granules were formed, and the mature cells contained two populations of cytochemically distinct granules. All granules of mature eosinophils were peroxidasepositive. In mature basophils, some granules were clearly peroxidase-positive; others displayed variable density, making interpretation uncertain. Mast cells were never seen in blood, but were abundant in bone marrow; peroxidase was never found in their granules by either electron microscopic cytochemistry or a variety of light microscopic methods. Hence, these cells differ from basophils, not only in morphology but also in the enzyme content of their granules.
    Type of Medium: Electronic Resource
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