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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructure of Human Unfertilized Oocytes and Polyspermic Embryos in an IVF-ET Program (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 541 (1988), 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.1749-6632.1988.tb22274.x
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  • 2
    Electronic Resource
    Electronic Resource
    Human zona pellucida during in vitro fertilization: An ultrastructural study using saponin, ruthenium red, and osmium-thiocarbohydrazide (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 32 (1992), S. 51-61 
    Details
    ISSN: 1040-452X
    Keywords: Oocyte ; Polypronuclear ovum ; Fertilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The human zona pellucida (ZP) and its changes during in vitro fertilization in oocytes at different maturational stages and polypronuclear ova at one- to four-cells stages were studied by transmission electron microscopy (TEM) and correlative scanning electron microscopy (SEM). To define the microstructure of the ZP, its amorphous masking material was removed using a detergent (saponin), and its structural glycoproteins were stabilized with a cationic dye, ruthenium red, followed by osmium-thiocarbohydrazide treatment. These methods allowed in all samples the clear visualization of variously arranged networks of filaments composing the outer and inner surfaces of the ZP. These filaments were straight or curved, 0.1-0.4 μ in length and 10-14 nm thick as seen via TEM or 22-28 nm thick as seen via SEM (the difference in thickness was due to the presence of the metal coating for SEM). The filament arrangement was remarkably different between the inner and outer surfaces of the ZP and among the various stages studied. The filaments of the outer surface of the ZP were basically arranged in “large” and “tight” meshed networks. Mature oocytes and fertilized (polypronuclear) ova had a regular alternating pattern of wide and tight meshed networks of filaments. On the other hand, immature and atretic oocytes displayed almost exclusively a tight meshed network of filaments. The inner surface filaments of the ZP of unfertilized oocytes at any stage were arranged in repetitive structures characterized by numerous short and straight filaments anastomosing with each other and sometimes forming at the intersections small, rounded structures. After fertilization, the inner surface of the ZP displayed numerous areas where filaments fused together. Collectively, these data clearly reveal that oocyte maturation and fertilization in humans are accompanied by changes of ZP filaments arrangement, which may be relevant in the processes of binding, penetration, and selection of spermatozoa. © 1992 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080320109
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  • 3
    Electronic Resource
    Electronic Resource
    Is the sperm-binding capability of the zona pellucida linked to its surface structure? A scanning electron microscopic study of human in vitro fertilization (1988)
    Springer
    Journal of assisted reproduction and genetics 5 (1988), S. 134-143 
    Details
    ISSN: 1573-7330
    Keywords: oocyte ; zona pellucida ; in vitro fertilization ; scanning electron microscopy ; gamete interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The structure of the zona pellucida and the early interactions between human oocytes and spermatozoa were investigated in an in vitro fertilization program. Thirty-five mature (preovulatory) oocytes, 10 immature oocytes lacking a germinal vesicle, and 11 atretic oocytes which had not undergone fertilization at 10–20 hr after insemination were studied by light and scanning electron microscopy. Observed through employment of these techniques, the zona pellucida showed two basically different patterns: a mesh-like, spongy structure having wide and/or close meshes; and a compact, smooth surface. The smooth-surfaced zona was most commonly seen in the cultured oocytes belonging to the immature and atretic groups. These observations seem to show that the spongy appearance of the zona pellucida is related mainly to oocyte development and maturity. In this study, greater numbers of penetrating spermatozoa were noted on oocytes showing the mesh-like zona, in contrast to the presence of a few sperm flattened against its surface or the frank absence of sperm associated with oocytes having the more compact, smooth zona. It is likely that the condensation of the outer aspect of the zona pellucida causes a disorientation of sperm-binding sites, which would probably result in markedly reduced binding and penetration capacity with spermatozoa. These changes might ultimately lead to impairment of in vitro oocyte fertilizability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01131175
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  • 4
    Electronic Resource
    Electronic Resource
    The three-dimensional structure of the zona pellucida in growing and atretic ovarian follicles of the mouse (1989)
    Springer
    Cell & tissue research 257 (1989), S. 247-253 
    Details
    ISSN: 1432-0878
    Keywords: Zona pellucida ; Ovarian follicles ; Atresia ; Ultrastructure ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present study provides further details on the fine-structural three-dimensional architecture of the zona pellucida (ZP) in growing and atretic follicles of mice by use of ruthenium red in combination with the detergents Triton X100 and saponin. These detergents were used for extraction of the “soluble” fraction of the zonal proteins in an attempt to expose the “structural” zonal glycoproteins, which in turn can be viewed as minute three-dimensional networks upon transmission- and scanning electron-microscopic examination. By use of these methods, the ZP of growing follicles appeared to be formed by interconnected filaments which also bind to globular structures building up a three-dimensional lattice. In contrast, the ZP of stage I as well as other (II and III) stages of atretic follicles showed a structure characterized by the presence of closely packed granules connected with short filaments to form a close-mesh reticulum. This structural change of the ZP, which in the present study is also associated with the disappearance of “gap junctions” within the granulosa and cumulus cell population, might represent one of the early events involved in the onset of atresia. These changes, most probably depending on an altered secretory activity of both oocytes and follicle cells, might lead to a degradation of the ZP network structure and to its subsequent increased density (condensation). All these morphodynamic events eventually contribute to a sequestration of the oocyte in the early stage of atresia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261827
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  • 5
    Electronic Resource
    Electronic Resource
    Morphological studies of polycystic mouse ovaries induced by dehydroepiandrosterone (1985)
    Springer
    Cell & tissue research 240 (1985), S. 519-528 
    Details
    ISSN: 1432-0878
    Keywords: Polycystic mouse ovaries ; Hormone treatment ; Morphometry ; Gap junctions ; Ovary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Morphological alterations induced by dehydroepiandrosterone (DHA) were studied in polycystic mouse ovaries (PCO). Treated mice showed ovulatory failure and cystic changes; cysts and follicles in various stages of growth and atresia were present although corpora lutea were absent. The levels of testosterone, dihydrotestosterone, 3α- and 3β-androstanediol, estrone and androstenedione increased, whereas estradiol was not detectable. The ultrastructure of granulosa cells in healthy and atretic follicles was similar to that of control animals, although the membrana granulosa in cysts was reduced to a monolayer of flattened cells. The theca interna of healthy and atretic follicles and ovarian cysts showed ultrastructural signs of abnormal steroidogenic stimulation. No significant differences (0.7〈P〈0.8) were found between the extensive surface area of gap junctions of healthy follicles of control and DHA-treated animals. On the P-face of granulosa cells of large healthy follicles, meandering strands of tight junctional particles were observed; their average length was significantly longer than those in healthy follicles of control animals (P〈0.001). This increase was probably related to the large amounts of androgens present in the treated animals. Theca interna cells possessed small gap junctions; no significant differences (P〉0.9) in gap-junction surface area were observed between DHA-treated and control animals. These results suggest that the size of gap junctions is probably unrelated to the steroidogenic activities of theca cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216340
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