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  • 1
    Electronic Resource
    Electronic Resource
    Developmental control of human preimplantation embryos: A comparative approach (1988)
    Springer
    Journal of assisted reproduction and genetics 5 (1988), S. 347-362 
    Details
    ISSN: 1573-7330
    Keywords: developmental control ; human preimplantation embryo ; embryonic genome activation ; cell lineage segregation ; regulation of ploidy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The period for which oocyte-derived factors are engaged in the control of human embryonic development involves at least the first four cell cycles after fertilization. The maternal-embryonic transition in human 8-to 16-cell embryos is a relatively vulnerable process, the failure of which entails developmental arrest of the given blastomere. The very early cellular differentiative events in human embryos, including blastomere surface polarization and segregation of the inner cell mass and trophectoderm cell lineages, appear to be dependent largely on the maternal genetic program. However, the embryonic genome is required for the formation of the blastocyst cavity, which is necessary to allow further differentiation of the first two embryonic tissues. Blastomeres with major developmental defects are removed by fragmentation and their loss is compensated by proliferation of remaining normal blastomeres. This mechanism is also mainly responsible for the regulation of ploidy through elimination of aneuploid blastomeres. The data presented suggest that embryos of individual mammalian species may differ in the timing of relevant developmental changes at the cellular and molecular levels. This should be taken into account when findings obtained on embryos of one species are used to anticipate the behavior of embryos of another species under identical conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01129571
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  • 2
    Electronic Resource
    Electronic Resource
    Control of the fertilization process by the egg coat: How does it work in humans (1992)
    Springer
    Journal of assisted reproduction and genetics 9 (1992), S. 313-317 
    Details
    ISSN: 1573-7330
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01203952
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  • 3
    Electronic Resource
    Electronic Resource
    Mouse oocyte maturation is affected by lithium via the polyphosphoinositide metabolism and the microtubule network (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 38 (1994), S. 187-199 
    Details
    ISSN: 1040-452X
    Keywords: Mouse oocyte ; Meiosis ; Lithium ; InsP3 ; myo-inositol ; Chromatin ; Microtubules ; Cell cycle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The incubation of mechanically denuded mouse oocytes in medium containing LiCl delayed both germinal vesicle breakdown (GVBD) and polar body extrusion in a dose-dependent and reversible manner. When myo-inositol alone was added to the culture medium, we observed that it accelerated GVBD and increased the rate of polar body extrusion, whereas, when combined with LiCl, the normal timing of GVBD was recovered. In the same way, when inositol trisphosphate (InsP3) was microinjected into the ooplasma, we observed an important improvement of the rate of GVBD, as compared to control oocytes, and prevention of lithium inhibition. However, neither myo-inositol nor InsP3 were able to rescue totally the oocytes from the negative effect of lithium on polar body extrusion. Moreover, lithium induced some important changes in microtubule and chromosome organizations. Before extrusion of the first polar body, the reduction of the spindle size or the appearance of short individualized chromosomes dispersed around a large aster of microtubules were often observed, whereas, after polar body extrusion, the spindle appeared smaller and chromosomes were often trapped in the midbody. Thus lithium affects mouse oocyte maturation at two different levels: GVBD and polar body extrusion. Whereas the former seems to be affected via polyphosphoinositide turnover, the latter is InsP3-independent and seems to be influenced negatively via underdevelopment of microtubular structures. © 1994 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080380210
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  • 4
    Electronic Resource
    Electronic Resource
    Differential sensitivity of progesterone- and zona pellucida-induced acrosome reactions to pertussis toxin (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 34 (1993), S. 183-189 
    Details
    ISSN: 1040-452X
    Keywords: Progesterone ; Zona pellucida ; Acrosome reaction ; Ca2+ influx ; Pertussis toxin ; G proteins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Pertussis toxin-sensitive guanine nucleotide-binding regulatory proteins (G proteins) have previously been shown to mediate the zona pellucida-induced acrosome reaction in mammalian sperm. In this study we compared the inhibitory effect of pertussis toxin on the zona-induced acrosome reaction in human spermatozoa with that on the reaction induced by progesterone, another physiological acrosome reaction-promoting stimulus associated with the ovulated oocyte. Up to the concentration of 1 μg/ml, pertussis toxin did not produce any direct effects on the acrosome reaction frequency nor did it influence sperm movement and viability. However, preincubation of spermatozoa with the toxin at a concentration of 100 ng/ml completely abolished the increase in the acrosome reaction frequency upon subsequent exposure to solubilized zona pellucida material. In contrast, the same treatment did not impair the ability of spermatozoa to initiate the acrosome reaction in response to progesterone. Moreover, the preincubation with pertussis toxin did not modify the changes in the intracellular concentration of calcium ions occurring after progesterone addition. These data suggest that different physiological stimuli may utilize different signal transduction pathways to induce the human sperm acrosome reaction. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080340210
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  • 5
    Electronic Resource
    Electronic Resource
    Sperm-induced calcium oscillations of human oocytes show distinct features in oocyte center and periphery (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 41 (1995), S. 259-263 
    Details
    ISSN: 1040-452X
    Keywords: Ca2+ stores ; Ca2+ oscillations ; Ca2+-induced Ca2+ release ; Fertilization ; Oocyte activation ; Human ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Temporal and spatial characteristics of explosive periodic increases (spikes) of intracellular free Ca2+ concentration ([Ca2+]i) induced by sperm in human oocytes (Ca2+ oscillations) were analyzed by confocal laser scanning microscopy and compared to Ca2+ oscillations induced in oocytes by the thiol reagent thimerosal. During the steady-state period of sperm-induced Ca2+ oscillations, each individual [Ca2+]i spike invariably began from a focus in oocyte periphery and spread throughout the entire peripheral region before propagating to the central ooplasm. This peripheral Ca2+ wave was immediately followed by an explosive [Ca2+]i increase in the central ooplasm. However, this central [Ca2+]i rise only peaked when [Ca2+]i in the peripheral ooplasm was already on the decline. Moreover, the peak [Ca2+]i values were always considerably higher in the oocyte center than in the periphery. In contrast, thimerosal-induced Ca2+ oscillations did not show this particular form of propagation. These data show that sperm-induced Ca2+ oscillations have a unique pattern of spatial dynamics and suggest that the bulk of Ca2+ mobilized during each spike is released from stores that have a relatively high threshold for Ca2+-induced Ca2+ release (CICR). These stores are poorly developed, if not absent, in the oocyte cortex, and CICR from them is triggered by previous CICR from another type of store with a lower threshold that are preferentially located in the oocyte cortex and act as a detonator. © 1995 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080410217
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  • 6
    Electronic Resource
    Electronic Resource
    Calcium Signaling in Human Preimplantation Development: A Review (1999)
    Springer
    Journal of assisted reproduction and genetics 16 (1999), S. 216-220 
    Details
    ISSN: 1573-7330
    Keywords: calcium signaling ; preimplantation development ; human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: Cell cycle-related calcium signals, bearing some similarity to those previously described in other animal species, have also been observed in human preimplantation embryos. These signals follow those occurring in both gametes during the period preceding fertilization and those induced by the fertilizing spermatozoon in the oocyte after gamete fusion. Even though the signals occurring during each of these distinct developmetal periods have different temporal and spatial characteristics, there may be a relationship between them; in fact, abnormalities of calcium signals occurring in an earlier developmental period may be at the origin of abnormal signals during later developmental periods. Methods: Possible mechanisms by which inadequate or truncated calcium signals can impair embryo development are discussed. Results: These mechanisms include complete failure of the second meiotic division, leading to triploidy; incomplete failure of the second meiotic division, leading to de novo chromosomal numerical abnormalities; abnormal pronuclear development and function; abnormalities of the blastomere cell cycle, possibly leading to embryo cleavage arrest; and problems with blastomere allocation to embryonic cell lineages, leading to disproportionate development of the inner cell mass and trophectoderm derivatives, which can be the origin of implantation failure or miscarriage. Conclusions: Future research should make it possible to decipher the nature of normal developmental signals, to determine the key checkpoints at which these signals are required to prevent the switch to apoptosis, and to examine the possibilities of therapeutic action at these checkpoints to rescue the endangered embryo for normal development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020321024973
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  • 7
    Electronic Resource
    Electronic Resource
    Nucleolar transformations in the human oocyte after completion of growth (1983)
    New York, NY : Wiley-Blackwell
    Gamete Research 8 (1983), S. 267-277 
    Details
    ISSN: 0148-7280
    Keywords: nucleolar structure ; RNA metabolism ; oocyte ; human ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Nucleolar ultrastrure was studied in fully grown human oocytes obtained from multilaminar preantral follicles and from follicles at different stages of antrum formation. Selective staining for ribonucleoproteins and 3H-uridine labeling were used in attempt to better understand the nature and functional significance of homogeneous dense nucleoli found in oocytes from large antral follicles.There was an apparent increase in the radio of nucleonema to nucleolar interstices, accompanied by a gradual degranulation of the nucleolonema during early stages of antrum fromation. The process of nucleolar homogenization continued in oocytes from medium-size antralfollicles, island of more tightly packed fibrils being hybothesized to represent persisting active transcription units. Entirely filamentous and homogeneous nucleoli were typical for oocytes from large antral follicles. They were demonstrated to ribonucleoprotein filaments embedded in pale- staining matrix. They were demonstrated to contain newly synthesized RNA after a 30-min pulse with 3H-uridine. The described nucleolar transformations are interpreted as acorrelate of nucleolar transition from a site of RNA synthesis into a site of RNA Storage during in human oocyte preovulatory development.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120080307
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  • 8
    Electronic Resource
    Electronic Resource
    Development of human male pronucleus: Ultrastructure and timing (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 24 (1989), S. 135-149 
    Details
    ISSN: 0148-7280
    Keywords: sperm nucleus ; nucleolar development ; zona-free eggs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The process of human male pronuclear formation was studied using an experimental model based on in vitro inseminated human zona-free eggs prepared from oocytes that failed to fertilize in a clinical in vitro fertilization program. The main ultrastructural changes in penetrated sperm nuclei transforming into pronuclei were used to define four stages of pronuclear development. The first two stages, representing partial (Stage 1) and total (Stage 2) sperm chromatin decondensation, appeared as early as 1 hr after mixing of gametes. This rapid initial phase was followed by a more lengthy array of events leading to transformation of decondensed sperm nuclei into fully developed male pronuclei (Stages 3 and 4). Stage 3 was characterized by reformation of the nuclear envelope, reorganization of chromatin, and the assembly of nuclcolar precursors. It was not completed until 12 hr after in vitro insemination when fully developed male pronuclei (Stage 4) were first observed. In some eggs pronuclei did not reach Stage 4 at all. The results of this study provide a morphological background for further research into molecular aspects of human male pronuclear development and its regulation.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120240203
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  • 9
    Electronic Resource
    Electronic Resource
    From the cellular to the molecular dimension: The actual challenge for human fertilization research (1986)
    New York, NY : Wiley-Blackwell
    Gamete Research 13 (1986), S. 47-89 
    Details
    ISSN: 0148-7280
    Keywords: human fertilization ; molecular biology ; sperm capacitation ; egg preovulatory development ; gamete interaction ; gamete antigens ; humster test ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120130106
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  • 10
    Electronic Resource
    Electronic Resource
    Human nonovulatory oocyte-cumulus complexes: Ultrastructure, macromolecular synthesis, and developmental potential (1984)
    New York, NY : Wiley-Blackwell
    Gamete Research 9 (1984), S. 153-165 
    Details
    ISSN: 0148-7280
    Keywords: nonovulatory follicle ; oocyte ; cumulus ; RNA ; protein ; human ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Human nonovulatory oocyte-cumulus complexes were obtained from large antral follicles 34 h after the injection of hCG. Their ultrastructure, RNA and protein synthesis, and the ability of oocyte maturation and subsequent fertilization in vitro were the subject of this study. The oocyte nucleus was situated in the cell periphery, possessing one or two dense nucleoli. Intranucleolar vacuoles were sometimes present. Mitochondria and smooth endoplasmic reticulum were the most abundant cytoplasmic structures. The number of cortical granules was rather low. Cumulus cells showed responsiveness to exogeneous hCG/endogeneous LH stimulation as morphologic signs of the oocyte-cumulus uncoupling and of the early luteinization. Furthermore, the oocytes were capable of meiotic maturation in vitro, and following subsequent in vitro insemination the majority of them were penetrated by spermatozoa. However, polyspermy was detected in most cases, and cleavage was not achieved. A developmental defect of nonovulatory oocytes was suggested by an extremely low level of RNA synthesis while continuing active protein synthesis by nonovulatory oocytes was demonstrated. In contrast, the associated cumulus cells synthesized both RNA and protein, suggesting that the majority of granulosa cells of the nonovulatory follicles was probably unaltered. It is hypothesized that the development of nonovulatory follicles after induction of ovulation might reveal the developmental pattern which would lead, in some cases, to ovulation of nonviable human oocytes both in stimulated and natural cycles.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120090205
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