The limited importance of pronuclear scoring of human zygotes

James, Amy; Hennessy, Sasha; Reggio, B.C.; Wiemer, Klaus E.; Larsen, F.W.; Cohen, Jacques

doi:10.1093/humrep/del013

Cited by 54 publications

(38 citation statements)

References 44 publications

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“…Finding the most reliable marker of developmental competence in early embryos is still a matter of quest and debate among researchers. The number, morphology and position of pronuclei are often evaluated to estimate embryo quality in humans [5]; however, controversial data regarding these selection markers have also been reported [6,7]. Moreover oocytes of large farm animals such as pigs and cattle contain a high number of lipid droplets that completely block the visibility of pronuclei using traditional microscopy.…”

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confidence: 99%

Relationship Between the Length of Cell Cycles, Cleavage Pattern and Developmental Competence in Bovine Embryos Generated by <i>In Vitro</i> Fertilization or Parthenogenesis

Somfai

Inaba

Aikawa

et al. 2010

Journal of Reproduction and Development

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Abstract. This study was conducted to study the kinetics of initial cell divisions in relation with the cleavage patterns in viable (with the ability to develop to the blastocyst stage) and non-viable bovine embryos and parthenotes. The kinetics of in vitro development and cleavage patterns were observed by time lapse cinematography. The length of the first and second but not third cell cycle differed significantly between the viable and non-viable embryos after IVF or parthenogenesis. Viable embryos had significantly shorter first and second cell cycles than non-viable ones. The presence of fragments, protrusions and unequally-sized blastomeres was associated with an extended one-cell stage and reduced ability to develop to the blastocyst stage; however, the lengths of the second and third cell cycles were not altered. Oocytes showing direct division from one cell to 3 or 4 blastomeres showed similar developmental ability and embryonic cell numbers to those showing normal division, although, with a high frequency of chromosomal abnormalities. Our results suggest that the differences in the first cell cycles between viable and non-viable embryos were not sperm-related, whereas direct cleavage of 1-cell embryos to 3 or more blastomeres and protrusion formation are related to sperm-driven factors. The length of the first and second cell cycles and the cleavage pattern should be examined simultaneously to predict developmental competence of embryos at early cleavage stages. Key words: Bovine, Cleavage pattern, Developmental kinetics, Embryo, In vitro culture, Time lapse cinematography (J. Reprod. Dev. 56: [200][201][202][203][204][205][206][207] 2010) ecent progress in the improvement of in vitro embryo production (IVP) systems allows us to produce large quantities of bovine embryos [1]. Nevertheless, the developmental competence of embryos produced by IVP is still inferior to that of in vivo produced embryos due to by different stresses resulting from the imperfection of the IVP systems in imitating in vivo conditions [2,3]. Selection of embryos with good developmental competence is essential to achieve high success rates by transfer of embryos, especially when only one or a very few embryos are transferred into a surrogate mother at one time, such as in humans and cattle. The transfer of mammalian embryos at early cleavage stages (e.g., at the 1-8 cell stage) may have the advantage of avoiding stresses caused by the culture systems. Human embryos produced by assisted reproduction technology are still often selected and transferred at the cleavage stage [4]. Finding the most reliable marker of developmental competence in early embryos is still a matter of quest and debate among researchers. The number, morphology and position of pronuclei are often evaluated to estimate embryo quality in humans [5]; however, controversial data regarding these selection markers have also been reported [6,7]. Moreover oocytes of large farm animals such as pigs and cattle contain a high number of lipid droplets that completely blo...

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mentioning

confidence: 99%

Relationship Between the Length of Cell Cycles, Cleavage Pattern and Developmental Competence in Bovine Embryos Generated by <i>In Vitro</i> Fertilization or Parthenogenesis

Somfai

Inaba

Aikawa

et al. 2010

Journal of Reproduction and Development

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“…An important contribution in this field comes from studies on pronuclear or nucleolar behavior and morphology (11)(12)(13)(14)(15)(16)(17)(18)(19). Nucleoli are the sites of the synthesis of pre-rRNA, and ribosomal RNA (rRNA) is necessary for the translational process whereby the embryonic genome becomes fully activated (20).…”

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confidence: 99%

Limited importance of pre-embryo pronuclear morphology (zygote score) in assisted reproduction outcome in the absence of embryo cryopreservation

Nicoli

Valli

Girolamo

et al. 2007

Fertility and Sterility

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“…However, other studies highlighted the limited prognostic value of the pronuclear score in assisted reproduction outcome [31][32][33][34].…”

Section: Discussionmentioning

confidence: 99%

The combination of pronuclear and blastocyst morphology: a strong prognostic tool for implantation potential

Braga

Setti

Figueira

et al. 2013

J Assist Reprod Genet

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Purpose To (i) investigate a possible association between different features of pronuclear (PN) morphology and different features of blastocyst morphology, (ii) evaluate the combination of PN and blastocyst morphologies as a predictive factor for ICSI outcomes and (iii) identify possible contributing factors to poor PN morphology. Methods This study included 908 normally fertilised zygotes reaching full blastocyst stage, obtained from 350 patients undergoing ICSI cycles, in which the implantations rates were 0 % or 100 %. The influence of PN morphology on blastocyst morphology and on the rates of pregnancy and miscarriage was investigated. Embryos were graded and split into three groups, taking into consideration both the PN and the blastocyst status. The pregnancy rate was compared among these groups. Results Inner cell mass (ICM) alterations were correlated with the number of nucleolar precursor bodies (NPB), while trophectoderm alterations were correlated with the size of the pronuclei and the distribution of the NPB. The distribution of the NPB had an impact on the chances of pregnancy. A significant difference was observed among the groups regarding the pregnancy rate. The maternal age, number of aspirated follicles and number of retrieved oocytes influenced the incidence of PN defects. Conclusions These findings suggest that a lower oocyte yield may lead to higher-quality PN zygotes. In addition, different PN features may influence further embryo development, especially the quality of the blastocyst. Moreover, the association between PN and blastocyst morphology may be used as a prognostic tool for implantation.

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The limited importance of pronuclear scoring of human zygotes

Cited by 54 publications

References 44 publications

Relationship Between the Length of Cell Cycles, Cleavage Pattern and Developmental Competence in Bovine Embryos Generated by <i>In Vitro</i> Fertilization or Parthenogenesis

Relationship Between the Length of Cell Cycles, Cleavage Pattern and Developmental Competence in Bovine Embryos Generated by <i>In Vitro</i> Fertilization or Parthenogenesis

Limited importance of pre-embryo pronuclear morphology (zygote score) in assisted reproduction outcome in the absence of embryo cryopreservation

The combination of pronuclear and blastocyst morphology: a strong prognostic tool for implantation potential

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