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Advances in embryo selection methods.

Ajduk A, Zernicka-Goetz M - F1000 Biol Rep (2012)

Bottom Line: Despite many recent advances in the field of reproductive biology and medicine, the efficiency of in vitro fertilization procedures remains relatively low.Here, we compare various methods currently used for assessing embryonic viability, such as examination of embryonic morphology, quality of the genetic material, or metabolism.Additionally, we discuss novel procedures for embryonic assessment based on advanced time-lapse imaging techniques, which show great promise and may lead to increased in vitro fertilization efficiencies.

View Article: PubMed Central - PubMed

ABSTRACT
Despite many recent advances in the field of reproductive biology and medicine, the efficiency of in vitro fertilization procedures remains relatively low. There is a need for a reliable and non-invasive method of embryo selection to ensure that only embryos with the highest developmental potential are chosen for transfer to mothers-to-be. Here, we compare various methods currently used for assessing embryonic viability, such as examination of embryonic morphology, quality of the genetic material, or metabolism. Additionally, we discuss novel procedures for embryonic assessment based on advanced time-lapse imaging techniques, which show great promise and may lead to increased in vitro fertilization efficiencies.

No MeSH data available.


Analysis of fertilization-triggered cytoplasmic movements in mouse zygotesMouse eggs are subjected to time-lapse imaging (1 frame every 10 seconds for 2.5 hours) immediately after fertilization [37]. Acquired images are analysed by the particle image velocimetry method that follows patterns of contrasts between subsequent images and calculates how they move. The sum of all displacement vectors calculated for the zygote in a given time-point (i.e. mean cytoplasmic speed) is plotted over time. The graph shows when fast cytoplasmic movements occurred in the embryo. Mean interval between the fast movements (in red) and mean speed in periods inbetween the fast movements (mean basal speed, in blue) are indicative of developmental potential of the embryo.
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fig-002: Analysis of fertilization-triggered cytoplasmic movements in mouse zygotesMouse eggs are subjected to time-lapse imaging (1 frame every 10 seconds for 2.5 hours) immediately after fertilization [37]. Acquired images are analysed by the particle image velocimetry method that follows patterns of contrasts between subsequent images and calculates how they move. The sum of all displacement vectors calculated for the zygote in a given time-point (i.e. mean cytoplasmic speed) is plotted over time. The graph shows when fast cytoplasmic movements occurred in the embryo. Mean interval between the fast movements (in red) and mean speed in periods inbetween the fast movements (mean basal speed, in blue) are indicative of developmental potential of the embryo.

Mentions: Due to recent advances in non-invasive time-lapse imaging established in mouse embryos [32], we can now follow the dynamics of embryo divisions and other fertilization-triggered events and correlate them with the developmental potential of the embryos. The last two years have seen two studies employing this technique in a very different way. A team at Stanford University has shown that the timing and synchrony of the first two embryonic divisions are predictive of developmental potential of human embryos (Figure 1) [33]. The authors reported that embryos with a very long first cytokinesis, with a prolonged or an atypically short interval between first and second division or with highly asynchronous divisions of two-cell blastomeres, fail to reach the blastocyst stage. This accords with previous observations, in which timely pronuclear formation and subsequent first cleavage correlated with higher quality of human embryos [34-36]. A completely different approach has been developed by our team at University of Cambridge working collaboratively with teams at Oxford and Cardiff Universities (Figure 2) [37]. In this work, we showed that fertilization of mouse eggs triggers abrupt, repetitive cytoplasmic movements that correlated with Ca2+ oscillations (also triggered by sperm) and depended on the functionality of the cytoskeleton. Moreover, the cytoplasmic flows were predictive of the developmental potential of the embryos. Embryos that showed very frequent increases in cytoplasmic movements (indicating very frequent Ca2+ oscillations) and low cytoplasmic speeds in the intervening periods (reflecting low quality of the actin cytoskeleton) were three-fold less successful in developing to pups than embryos displaying average values of these parameters. Although both methods still have to be tested in a clinical environment and subjected to randomised controlled trials to demonstrate improved live birth outcomes, they offer great hope for more reliable assessment of embryonic quality.


Advances in embryo selection methods.

Ajduk A, Zernicka-Goetz M - F1000 Biol Rep (2012)

Analysis of fertilization-triggered cytoplasmic movements in mouse zygotesMouse eggs are subjected to time-lapse imaging (1 frame every 10 seconds for 2.5 hours) immediately after fertilization [37]. Acquired images are analysed by the particle image velocimetry method that follows patterns of contrasts between subsequent images and calculates how they move. The sum of all displacement vectors calculated for the zygote in a given time-point (i.e. mean cytoplasmic speed) is plotted over time. The graph shows when fast cytoplasmic movements occurred in the embryo. Mean interval between the fast movements (in red) and mean speed in periods inbetween the fast movements (mean basal speed, in blue) are indicative of developmental potential of the embryo.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3369238&req=5

fig-002: Analysis of fertilization-triggered cytoplasmic movements in mouse zygotesMouse eggs are subjected to time-lapse imaging (1 frame every 10 seconds for 2.5 hours) immediately after fertilization [37]. Acquired images are analysed by the particle image velocimetry method that follows patterns of contrasts between subsequent images and calculates how they move. The sum of all displacement vectors calculated for the zygote in a given time-point (i.e. mean cytoplasmic speed) is plotted over time. The graph shows when fast cytoplasmic movements occurred in the embryo. Mean interval between the fast movements (in red) and mean speed in periods inbetween the fast movements (mean basal speed, in blue) are indicative of developmental potential of the embryo.
Mentions: Due to recent advances in non-invasive time-lapse imaging established in mouse embryos [32], we can now follow the dynamics of embryo divisions and other fertilization-triggered events and correlate them with the developmental potential of the embryos. The last two years have seen two studies employing this technique in a very different way. A team at Stanford University has shown that the timing and synchrony of the first two embryonic divisions are predictive of developmental potential of human embryos (Figure 1) [33]. The authors reported that embryos with a very long first cytokinesis, with a prolonged or an atypically short interval between first and second division or with highly asynchronous divisions of two-cell blastomeres, fail to reach the blastocyst stage. This accords with previous observations, in which timely pronuclear formation and subsequent first cleavage correlated with higher quality of human embryos [34-36]. A completely different approach has been developed by our team at University of Cambridge working collaboratively with teams at Oxford and Cardiff Universities (Figure 2) [37]. In this work, we showed that fertilization of mouse eggs triggers abrupt, repetitive cytoplasmic movements that correlated with Ca2+ oscillations (also triggered by sperm) and depended on the functionality of the cytoskeleton. Moreover, the cytoplasmic flows were predictive of the developmental potential of the embryos. Embryos that showed very frequent increases in cytoplasmic movements (indicating very frequent Ca2+ oscillations) and low cytoplasmic speeds in the intervening periods (reflecting low quality of the actin cytoskeleton) were three-fold less successful in developing to pups than embryos displaying average values of these parameters. Although both methods still have to be tested in a clinical environment and subjected to randomised controlled trials to demonstrate improved live birth outcomes, they offer great hope for more reliable assessment of embryonic quality.

Bottom Line: Despite many recent advances in the field of reproductive biology and medicine, the efficiency of in vitro fertilization procedures remains relatively low.Here, we compare various methods currently used for assessing embryonic viability, such as examination of embryonic morphology, quality of the genetic material, or metabolism.Additionally, we discuss novel procedures for embryonic assessment based on advanced time-lapse imaging techniques, which show great promise and may lead to increased in vitro fertilization efficiencies.

View Article: PubMed Central - PubMed

ABSTRACT
Despite many recent advances in the field of reproductive biology and medicine, the efficiency of in vitro fertilization procedures remains relatively low. There is a need for a reliable and non-invasive method of embryo selection to ensure that only embryos with the highest developmental potential are chosen for transfer to mothers-to-be. Here, we compare various methods currently used for assessing embryonic viability, such as examination of embryonic morphology, quality of the genetic material, or metabolism. Additionally, we discuss novel procedures for embryonic assessment based on advanced time-lapse imaging techniques, which show great promise and may lead to increased in vitro fertilization efficiencies.

No MeSH data available.