Results 251 to 260 of about 48,631 (292)
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Oocyte activation in invertebrates and humans
Zygote, 1994Oocytes are metabolically repressed cells that, in most cases, require a signal from the fertilising spermatozoon to trigger activation. Physiological competence of the activated oocyte, a prerequisite for early embryogenesis, depends, therefore, not only on the quality of the oocyte, but also on the quality of the spermatozoon (Dale, 1983; Tosti &
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Age dependence of bovine oocyte activation
Gamete Research, 1989AbstractThe ability of bovine oocytes to undergo parthenogenetic activation using either a Ca++‐Mg++‐H+ ionophore (A23187) or electric shock was investigated, as a prelude to understanding activation potential following nuclear transfer into ooplasm. Oocytes were collected from slaughterhouse ovaries by aspiration of 1–5‐mm follicles.
C B, Ware +3 more
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The involvement of calcium in the activation of mammalian oocytes
Experimental Cell Research, 1978Mouse oocytes with cumulus cells intact were parthenogenetically activated following release from the oviduct into calcium-free medium. The proportion of activated oocytes increased with post ovulatory age both for oocytes initially exposed to calcium-free and calcium-containing medium (control).
D G, Whittingham, G, Siracusa
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2022
Against all expectations, the presence of a carefully selected normal spermatozoon does not guarantee oocyte activation/fertilization. In contrast, some ICSI cycles will have to face no or low fertilization in several consecutive cycles. Both sperm- and oocyte-derived problems may account for such a dilemma. In case of physiological activation problems,
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Against all expectations, the presence of a carefully selected normal spermatozoon does not guarantee oocyte activation/fertilization. In contrast, some ICSI cycles will have to face no or low fertilization in several consecutive cycles. Both sperm- and oocyte-derived problems may account for such a dilemma. In case of physiological activation problems,
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Activation of amphibian oocytes by sperm extracts
Zygote, 2008SummaryIn the fertilization of most animals, egg activation is accompanied by an increase in cytoplasmatic Ca2+; however, the mechanism through which the fertilizing sperm induce this phenomenon is still controversial. An increase in intracellular free Ca2+is required to trigger egg activation events, a process that includes cortical granule exocytosis,
F, Bonilla +5 more
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RNase A activity in Japanese quail oocytes
Zygote, 1996SummaryThe presence of RNase A activity was studiedin vitroin homogenates of quail oocytes and early embryos using [3H]poly(U) as a substrate. The activity was measured by adsorption of the undegraded substrate onto DE-81 filter paper discs and by chromatographic separation on a Sephadex G-50 column.
U, Stepińska +2 more
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Use of strontium for bovine oocyte activation
Theriogenology, 2005Strontium efficiently activates mouse oocytes, however, there is limited information on its use in cattle. Thus, the objective of this study was to establish a suitable protocol for activating bovine oocyte with strontium. For pronuclear development, the absence of calcium and magnesium in the activation medium (TALP) with 10 and 50 mM strontium (34.4 ...
Méo, Simone Cristina +4 more
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Sperm-activated currents in ascidian oocytes
Developmental Biology, 1987Using patch electrodes and the whole-cell recording technique to study fertilization currents in ascidian oocytes under voltage clamp, this paper shows that between -85 and 0 mV the currents are inward with an initial peak ranging from 50 to 600 pA. Voltages more positive than 0 mV inhibit initiation of the fertilization current, but by allowing the ...
L J, DeFelice, M J, Kell
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Acetylcholinesterase activity of Xenopus laevis oocytes
Neuroscience, 1983The cholinesterase activity of Xenopus laevis oocytes was assessed using [3H]acetylcholine in a simple radiometric procedure. The cholinesterase activity of mature (stage V-Vl) oocytes was very sensitive to inhibition by the specific acetylcholinesterase inhibitor, BW284-C5l, and relatively insensitive to an inhibitor of non-specific, or ...
C B, Gundersen, R, Miledi
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Strategies for activating nuclear transfer oocytes
Reproduction, Fertility and Development, 1999The technique of nuclear transfer can have enormous applications in the fields of agriculture and biomedicine. This is especially true if a cell line that has been transformed can be used as a source of nuclei for the nuclear transfer. One major aspect of the nuclear transfer procedures is that of oocyte activation.
Z, Macháty, R S, Prather
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