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  • 1
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    Centrioles in the beginning of human development. (1991)
    National Academy of Sciences
    Details
    Publication Date: 1991-06-01
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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    PAPER CURRENT
  • 2
    Electronic Resource
    Electronic Resource
    Centriolar dynamics in the bovine embryo: inheritance and perpetuation of the sperm centrosome during fertilization and development (1999)
    Springer
    Protoplasma 206 (1999), S. 263-269 
    Details
    ISSN: 1615-6102
    Keywords: Centriole ; Centrosome ; Cow ; Embryo ; Fertilization ; Transmission electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Inheritance of the centrosome (centriole) and its behaviour during fertilization and embryogenesis of cattle is presented. The bovine embryo follows the human pattern of centriole behaviour, which is common to most animals including large mammals. Thus, most mammals obey Boveri's rule of paternal centrosomal inheritance and perpetuation, whereas the mouse is an exception to the rule, showing maternal inheritance. The sperm centrosome was traced from fertilization to the hatching blastocyst stage in the cow and its presence was confirmed at every stage of cleavage, as reported in the human. It is concluded that the bovine embryo is a more appropriate model than the mouse for research in fertilization and assisted-reproduction technology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01288214
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructural observations on cortical granules in human follicular oocytes cultured in vitro (1982)
    New York, NY : Wiley-Blackwell
    Gamete Research 5 (1982), S. 191-198 
    Details
    ISSN: 0148-7280
    Keywords: cortical granules ; ultrastructure ; oocyte maturation ; in vitro culture ; fertilizability ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The fine structure, distribution, and fate of cortical granules in human oocytes cultured in vitro are reported.Follicular maturation in women with blocked Fallopian tubes was induced by clomiphene citrate and human chorionic gonadotropin, and preovulatory eggs were obtained by improved methods of laproscopy and oocyte recovery. These oocytes were then inseminated and cultured in a modified Ham's F10 medium for 3 to 72 hr to assess their fertilizability.Cortical granules were observed in all 17 unfertilized oocytes investigated, which had completed various stages of meiotic maturation. A marked increase in their numbers was observed in oocytes cultured for 3 to 6 hr. There was no evidence of spontaneous cortical granule release in any of the oocytes studied.It is concluded that cortical maturation expressed by proliferation of cortical granules is as significant a criterion as nuclear maturation in assessing maturity and fertilizability of oocytes cultured in vitro. A short sojourn in culture before insemination could improve chances of normal fertilization and embryo development, which has been recently achieved in our laboratory.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120050209
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  • 4
    Electronic Resource
    Electronic Resource
    The effects of ultrarapid freezing on meiotic and mitotic spindles of mouse oocytes and embryos (1988)
    New York, NY : Wiley-Blackwell
    Gamete Research 21 (1988), S. 385-401 
    Details
    ISSN: 0148-7280
    Keywords: spindles ; oocytes ; embryos ; microtubules ; cryopreservation ; electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Preovulatory mouse oocytes and 2-cell embryos were frozen with dimethyl sulfoxide and propanediol by an ultrarapid method. The survival of frozen oocytes was low (33-34%) compared to that of 2-cell embryos (78-79%) with either cryoprotectant. Development to blastocysts after postthaw culture was about 7-15% for oocytes and 79-80% for the embryos.Ultrarapid freezing preserves cell structure quite well as revealed by electron microscopy, but meiotic oocytes and late 2-cell embryos undergoing mitosis showed evidence of spindle disorganization involving loss or clumping of microtubules resulting in some scattering of chromosomes. Embryos developed from frozen eggs showed clear evidence of micronuclear formation and incomplete incorporation of chromosomal material into main nuclei. These experiments confirm our observations on freezing of human oocytes and show that spindle microtubules are sensitive to freeze-thawing and that cryopreservation could cause chromosomal aberrations during early development. A cautious approach to the introduction of oocyte freezing in human in vitro fertilization (IVF) programs is advocated.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120210407
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  • 5
    Electronic Resource
    Electronic Resource
    The human pronuclear ovum: Fine strcture of monospermic and polyspermic fertilization in vitro (1985)
    New York, NY : Wiley-Blackwell
    Gamete Research 12 (1985), S. 385-398 
    Details
    ISSN: 0148-7280
    Keywords: in vitro fertilization ; pronuclear ova ; one-cell embryo ; monospermy ; polyspermy ; syngamy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The fine structure of pronuclear ova (monospermy and polyspermy) and one-cell embryos has been investigated in our IVF programme. Sixteen oocytes were collected at laparoscopy after appropriate hormonal stimulation and were matured and fertilized in vitro by methods that have given rise to normal pregnancies.Pronuclear ova showing monospermic fertilization had two vesicular pronuclei surrounded by aggregations of cellular organelles. The male pronucleus was closely associated with a sperm axoneme, while the female pronucleus was dismantling its envelope and condensing its chromatin ahead of its counterpart in late pronuclear ova. Each pronucleus had dispersed chromatin, dense compact nucleoli, and intranuclear annulate lamellae. Smooth endoplasmic reticulum, annulate lamellae, Golgi complexes, and mitochondria formed a conspicuous part of the perinuclear ooplasm. The one-cell embryos were either in syngamy or in the process of undergoing first cleavage. Positive evidence of cortical granule release and second polar bodies were detected in the perivitelline space. A block to polyspermy seemed to operate at the level of the inner zona.Dispermic and polyspermic ova had 3-16 pronuclei resembling those of monospermic ova and had sperm tails in the ooplasm. Sperm were also seen penetrating the inner zona and were occasionally found in the perivitelline space. Incomplete cortical granule release and early signs of cytoplasmic fragmentation were noted in polyspermic ova.Both normal and abnormal features of these ova are reported and compared with pronuclear structure in vivo and in vitro.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120120406
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  • 6
    Electronic Resource
    Electronic Resource
    Ultrastructure of cortical granule release and zona interaction in monospermic and polyspermic human ova fertilized in vitro (1982)
    New York, NY : Wiley-Blackwell
    Gamete Research 6 (1982), S. 225-234 
    Details
    ISSN: 0148-7280
    Keywords: in vitro fertilization ; electron microscopy ; cortical reaction ; zona reaction ; monospermy ; polyspermy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cortical granule release and interaction with the zona pellucida are reported in monospermic and polyspermic fertilized ova and early human embryos cultured in vitro.Twenty-seven preovulatory oocytes from women with tubal or idiopathic infertility were recovered by laparoscopy, after induction of follicular maturation with clomid and human chorionic gonadotropin. These were then inseminated with husband's or donor sperm, cultured for 3-72 hr, routinely fixed in glutaraldehyde/osmium and examined ultrastructurally.Evidence of cortical granule release was observed in all ova and embryos investigated and their contents were identified either at the egg surface or in the perivitelline space or interacting with the inner zona, apparently reinforcing its structure. The latter is very likely the morphological expression of the zona reaction.Delayed release was seen in certain regions of normally fertilized ova and particularly in polyspermic ova, where massive “explosions” of granules occurred. This was attributed to delayed cortical maturation. The mechanics of release were similar in both monospermic and polyspermic ova. Spontaneous dehiscence was also described in one injured unfertilized oocyte.The significance of the cortical and zona reactions as an effective block to polyspermy at the level of the inner zona, which becomes more impenetrable to supplementary sperm, is discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120060306
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  • 7
    Electronic Resource
    Electronic Resource
    Subzonal transfer of multiple sperm (MIST) into early human embryos (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 26 (1990), S. 253-260 
    Details
    ISSN: 1040-452X
    Keywords: Microinsemination ; Micromanipulation ; Fertilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Micronsemination sperm transfer (MIST) is a technique whereby sperm are transferred into the perivitelline space (PVS) with the aid of a micromanipulator. MIST is now used to investigate whether blastomere membranes of early human embryos are capable of fusing with the sperm as in the metaphase II oocyte. Between 10 and 30 sperm were transferred into 11 donated human embryos between pronuclear and 16 cell stage. After culture for 6-24 hr in vitro, the embryos were fixed for transmission electron microscopy (TEM). Both acrosome-intact and acrosome-reacted sperm were located in the PVS and between blastomeres. Sperm in the PVS were sometimes penetrating the inner regions of the zona. Sperm-blastomere membrane fusion was not observed, but sperm tail incorporation by phagocytosis was occasionally evident. Sperm heads incorporated into blastomeres were often located in membrane-bound vesicles. Both acrosome-intact and acrosome-reacted sperm heads were found in vacuoles. Acrosome-reacted sperm heads were lying passively in vacuoles or were undergoing degenerative changes at their surfaces. Sperm chromatin decondensation was not observed in any of the sperm heads that were detected in the blastomeres. The evidence presented clearly shows that sperm heads are incapable of expanding their chromatin to form typical male pronuclei following MIST into early human embryos.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080260309
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  • 8
    Electronic Resource
    Electronic Resource
    Assessment of the human sperm acrosome reaction using concanavalin a lectin (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 25 (1990), S. 247-257 
    Details
    ISSN: 1040-452X
    Keywords: Human spermatozoa ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A method for assessment of the human sperm acrosome reaction is reported using fluorescein isothiocyanate (FITC)-conjugated Concanavalin A (ConA). The technique involved labelling prefixed spermatozoa, where only those spermatozoa that showed a complete loss of the acrosome bound FITC-ConA to the acrosomal region. Competitive sugar binding studies demonstrated that binding of ConA lectin to the acrosomal area of human spermatozoa was inhibited in the presence of 0.2 M D-mannose. Staining with the supravital stain Hoechst 33258 (H258) concomitantly with FITC-ConA allowed determination of only those spermatozoa that had undergone a true and not degenerative acrosomal loss. Incubation of human spermatozoa with 0, 1, 5, and 25 μM calcium ionophore, A23187, for 60 min demonstrated that changes in acrosomal status due to the different treatment protocols may be determined by the dual-staining method. Electron microscopy studies revealed that gold-conjugated ConA bound specifically to the surface of the inner acrosomal membrane of acrosome-reacted spermatozoa. A significant correlation (r = +.97) between transmission electron microscopy (TEM) and FITC-ConA labelling methods of acrosomal status assessment was achieved. The simple ConA labelling procedure reported here therefore provides a reliabale method for quantitation of the physiological acrosome reaction of a population of human spermatozoa.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080250306
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  • 9
    Electronic Resource
    Electronic Resource
    Ultrastructure of early cleavage and yolk extrusion in the marsupial Antechinus stuartii (1988)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 195 (1988), S. 327-344 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fertilized egg and the two-cell stage and four-cell stage of the marsupial Antechinus stuartii were studied by transmission electron microscopy. The features that make the fertilized egg of Antechinus stuartii different from those of any eutherian mammal are (1) the presence of a shell and (2) the relatively large quantity and polarized distribution of cytoplasmic inclusions, including lipid, protein yolk bodies, and protein fibers. Mitochondria and vesicles of smooth endoplasmic reticulum are also polarized in distribution. Early cleavage differs from that of eutherians in several ways: (1) it occurs in the uterus; (2) there is extrusion of a large, single, membrane-bound yolk mass at first cleavage; and (3) blastomeres become separated after the second cleavage division and thus do not adhere by cell-to-cell contacts. Prior to the second division, blastomeres are connected to each other by remnants of the midbody and to the yolk mass by remnants of a cytoplasmic bridge. The yolk mass after extrusion is surrounded by plasma membrane and contains inclusions of lipid, protein yolk bodies, and fibers, as well as mitochondria and smooth endoplasmic reticulum. The blastomeres of the two-cell and four-cell stages also show intracellular polarization in the distribution of retained inclusions and organelles. Vesicles developing at the periphery of blastomeres and discharging their contents extracellularly increase in size and number from the fertilized egg to the four-cell stage. The discharged contents may be implicated in early development of the blastula cavity.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051950307
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  • 10
    Electronic Resource
    Electronic Resource
    Fine structure of early human embryos frozen with 1,2 propanediol (1988)
    New York, NY : Wiley-Blackwell
    Gamete Research 19 (1988), S. 253-263 
    Details
    ISSN: 0148-7280
    Keywords: cryopreservation ; IVF ; in vitro fertilization ; embryo-freezing ; ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Previous studies by a French group (Fertil Steril 44:645-651, 1985) have shown that two-to eight-cell human embryos can survive slow freeze-thawing with propanediol in a biological freezer. These embryos were assessed for morphological appearance by phase-contrast microscopy. We assessed the structure of 25 frozen-thawed one- to 12-cell embryos, obtained from our in vitro fertilization (IVF) and GIFT programmes, by phase-contrast and electron microscopy, using the same method of cryopreservation. One-fourth of the embryos examined had all cells intact, and more than one-half the embryos had over 50% of their cells well preserved. Some of these embryos had unequal blastomeres and cytoplasmic fragments. Ultrastructural assessment revealed good preservation of fine structure in the intact blastomeres of all embryos and maintenance of cell-to-cell contacts. Most cytoplasmic organelles, cell membranes, and nuclei were well preserved compared to nonfrozen controls. The cells that were cryoinjured showed varying degrees of disorganization of the cell membrane, cytosol, and cellular membranes, including swelling and disruption of the nuclear envelope. Disruption of the zona was somewhat rare. Small cytoplasmic fragments were less prone to cryoinjury than blastomeres. The use of propanediol for embryo cryopreservation seems to be feasible; frozen embryos with more than 50% cells intact have produced 10 pregnancies after embryo transfer (Fertil Steril 46:268-272, 1986). Replacement of 17 frozen embryos in seven patients has resulted in a twin pregnancy in Singapore. However, the effects of freezing on the mitotic spindles of embryonic cells need to be investigated further.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120190305
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