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  • 1
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    Effects of actinomycin D and cycloheximide on the nucleolar ultrastructure of porcine oocytes (1984)
    Wiley
    Details
    Publication Date: 1984-01-01
    Print ISSN: 0248-4900
    Electronic ISSN: 1768-322X
    Topics: Biology
    Published by Wiley
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    PAPER CURRENT
  • 2
    Electronic Resource
    Electronic Resource
    Ultrastructural aspects of in vitro fertilization in sheep
    Amsterdam : Elsevier
    Journal of Ultrastructure Research and Molecular Structure Research 98 (1988), S. 1-10 
    Details
    ISSN: 0889-1605
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0889-1605(88)80929-7
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  • 3
    Electronic Resource
    Electronic Resource
    Activity of maturation promoting factor in mammalian oocytes after its dilution by single and multiple fusions
    Amsterdam : Elsevier
    Developmental Biology 118 (1986), S. 176-181 
    Details
    ISSN: 0012-1606
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0012-1606(86)90085-0
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  • 4
    Electronic Resource
    Electronic Resource
    The site of the acrosome reaction during in vivo penetration of the sheep oocyte (1984)
    New York, NY : Wiley-Blackwell
    Gamete Research 10 (1984), S. 97-105 
    Details
    ISSN: 0148-7280
    Keywords: ultrastructure ; fertilization ; sheep ; oocytes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In vivo fertilization of sheep eggs has been studied by electron microscopy. Remnants of the acrosome reaction were present at the zona surface of every penetrated egg, indicating that the acrosome reaction in sheep occurs at the surface of the zona pellucida.To determine whether follicular oocytes could specifically bind spermatozoa, oocytes isolated from different size classes of antral follicles were transferred into the oviducts of mated ewes, recovered 4 hr 30 min later, and analyzed by electron microscopy. Oocytes from follicles up to 1 mm in diameter failed to bind spermatozoa and were not penetrated. In contrast, the zona of oocytes from follicles ≥ 2 mm in diameter induced the acrosome reaction. These oocytes were penetrated but failed to achieve cortical granule exocytosis and so to mount a block to polyspermy. Moreover, sperm nuclei incorporated into the ooplasm did not decondense although the sperm nuclear envelope was dispersed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120100202
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructure of in vivo fertilization in the goat (1987)
    New York, NY : Wiley-Blackwell
    Gamete Research 18 (1987), S. 191-199 
    Details
    ISSN: 0148-7280
    Keywords: caprine ; egg ; sperm penetration ; electron-microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In vivo fertilization of goat eggs has been studied by electron microscopy. Eggs were recovered from superovulated or natural cyclic goats, 32 to 52 hours after the onset of oestrus; only eggs recovered between 46 and 52 hours were fertilized.Spermatozoa penetrated the zona pellucida tangentially leaving vesiculated products of the acrosome reaction at the zona surface.As sperm penetrated into the ooplasm, the second meiotic division completed and cortical granule exocytosis occurred. However a few unreacted cortical granules usually remained in the cortex of the two fertilized eggs, adjacent to the plasma membrane.After swelling the two pronuclei presented similar ultrastructural morphology: they contained small, compact, agranular nucleoli and unevenly distributed chromatin. The cytoplasm in close vicinity to the apposed pronuclei contained large stacks of annulate lamellae, smooth endoplasmic reticulum, prominent Golgi complexes, as well as dense areas of unidentified material. The abundance of cytoplasmic organelles near the pronuclei might be the expression of intensive metabolic activity. Conversely, in the cortex of fertilized ova several large organelles-free cytoplasmic areas were randomly distributed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120180209
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  • 6
    Electronic Resource
    Electronic Resource
    Fine structure of sheep fertilization in vitro (1988)
    New York, NY : Wiley-Blackwell
    Gamete Research 19 (1988), S. 291-303 
    Details
    ISSN: 0148-7280
    Keywords: ultrastructure ; ovine egg ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The fertilization events of the sheep oocyte have been investigated by electron microscopy. Thirty-two oocytes recovered from the oviducts of superovulated ewes were fertilized in vitro by a procedure that has given rise to full embryonic development (Crozet et al.: Gamete Res 16:159-170, 1987) and were analyzed at different stages of fertilization.Sperm incorporation in the ooplasm occurred as early as 2 h postinsemination (PI). One hour later, a fertilization cone containing very few cytoplasmic organelles developed above the decondensing sperm chromatin. It was a transitory structure which disappeared when the male pronucleus (PN) was formed. The second meiotic division of the oocyte resumed soon after sperm incorporation; abstriction of the second polar body occurred by 3-4 h PI; the polar body constriction was associated with microfilaments.Both the male and female PN were formed at 5 h PI and were surrounded by nuclear envelopes containing pore complexes. The female PN was characterized by patches of condensed chromatin; the male PN was closely associated with the sperm neck and proximal midpiece. Thereafter the PN migrated toward the center of the egg, where the spindle of the first cleavage division was observed at 21 h PI.Dispermic ova analyzed at 2-4 h PI contained 2 decondensing sperm heads and 2 fertilization cones which have reached the same stage, thus suggesting that a few sperm may penetrate quite simultaneously. Multipronucleate eggs were characterized by disturbance of the PN migration.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120190308
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  • 7
    Electronic Resource
    Electronic Resource
    In vitro fertilization in the sheep: Effect of elevated calcium concentration at insemination (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 119-125 
    Details
    ISSN: 0148-7280
    Keywords: ovine ; in vitro fertilization ; calcium ; semen ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Oocytcs (n = 273), collected from superovulated ewes, were inseminated with in vitro capacitated spermatozoa from four rams [Crozet et al., 1987]. In each experiment, paral lel insemination was performed using aliquants from a single ejaculate in either our stan-dard fertilization medium DM-H-SS (a modification of Bracken's defined medium, buffered with HEPES and containing 20% v/v sheep serum) or in the same medium supplemented with calcium lactate (DM-H-SS + Ca). The measured total calcium con centrations were Ca++T = 2.74 mM in DM-H-SS medium and Ca++T = 8.74 mM in DM-H-SS + Ca; the ratio of free to total calcium in DM-H-SS was Ca++F/Ca++T = 0.85. Fertilization was assessed at 17 hours postinsemination.Variations in the ejaculates were observed for each of the four rams tested. When DM-H-SS + Ca was used, the percentages of fertilized (75% vs. 50%) and monospermic (58% vs. 41%) eggs were significantly enhanced compared with use of DM-H-SS. No improve ment was observed in control medium DM-H-SS + lac containing neutralized lactic acid. Supplementing the fertilization medium with calcium had no apparent effect on the inci dence of polyspermy.These experiments show that the fertilization rate achievable in vitro by individual ejaculates from various rams can be increased by raising the calcium concentration in the fertilization medium to a value much higher than that present in tuba! fluids from estrous ewes. Extended incubation in such a high calcium concentration is unnecessary for in vitro capacitation of ram spermatozoa.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120230111
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  • 8
    Electronic Resource
    Electronic Resource
    Distribution and role of microfilaments during early events of sheep fertilization (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 22 (1989), S. 411-425 
    Details
    ISSN: 0148-7280
    Keywords: actin ; egg ; cytochalasin D ; NBD-phallacidin ; anti-actin antibody ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The distribution of actin was studied during early events of sheep fertilization by fluorescence microscopy after staining with 7-nitrobenz-2-oxal-1.3 diazole (NBD)-phallacidin and anti-actin antibody and by electron microscopy after heavy meromyosin labelling. Unfertilized and fertilized eggs exhibited a continuous band of fluorescence with both NBD-phallacidin and anti-actin antibody. Unlike in mice, no high concentration of actin overlying the spindle was detected in ovulated sheep oocytes. At the site of sperm head incorporation, the fertilization cone developed above the decondensing male chromatin and was underlined by a submembranous area rich in microfilaments. A similar actin network was observed in the cortex of the second polar body.Cytochalasin D was used to investigate the role of actin during the fertilization process. This drug did not prevent sperm fusion and incorporation but inhibited polar body abstriction and fertilization cone development and retarded sperm tail incorporation. Moreover, in the presence of the drug, the anchorage of the metaphase II spindle at the surface of the egg was destroyed. The role of microfilaments in these early events is discussed.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120220407
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  • 9
    Electronic Resource
    Electronic Resource
    Electron microscopic study of the in vivo zona pellucida binding ability of epididymal ram spermatozoa (1986)
    New York, NY : Wiley-Blackwell
    Gamete Research 14 (1986), S. 225-234 
    Details
    ISSN: 0148-7280
    Keywords: spermatozoa-epididymis ; capacitation ; intrauterine insemination ; intratubal ova ; ram ; ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In the ram, spermatozoa develop the ability to initiate pregnancy only after reaching the body of the epididymis. To determine the zona pellucida binding ability of ram spermatozoa collected from different levels of the epididymis, sufficient numbers of motile sperm cells of different epididymal origin were inseminated surgically below the uterotubal junction of ewes at the time of ovulation. Intratubal ova were recovered 24 hr later, and those having spermatozoa attached to the zona were examined by transmission electron microscopy to assess the characteristics of the bound spermatozoa. Data indicate that the ability of the capacitated spermatozoa to adhere to the zona pellucida depends on sperm egg binding sites that develop on the acrosomal membranes from the apex to equatorial segment during epididymal transit.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120140306
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