Analysis of Oct-4 expression and ploidy in individual human blastomeres.
Oct-4, a decisive factor that maintains totipotency in murine embryonic and germ cells, is exclusively expressed in such cells. In mice, different levels of oct-4 expression in blastomeres predict development towards inner cell mass (ICM) (high oct-4) or trophectoderm (TE) (low oct-4). To address whether the mouse model also applies to human embryos, the cytoplasm of individual human blastomeres from normally and abnormally fertilized embryos was tested for Oct-4 expression by reverse transcription-polymerase chain reaction (RT-PCR). The nuclei of the same blastomeres were subjected to fluorescence in-situ hybridization (FISH) to determine ploidy. A significant difference in Oct-4 mRNA levels was revealed between blastomeres. The distribution of blastomeres with high Oct-4 levels varied according to the cleavage stage of the embryo: the more blastomeres, the lower the percentage with high Oct-4 levels. Aneuploid blastomeres did not exhibit lower Oct-4 mRNA levels than diploid ones. Thus, differential Oct-4 expression in individual human blastomeres appears to direct cells towards the ICM or TE lineages without regard to chromosomal status. Oct-4 might be used as a marker in preimplantation genetic diagnosis to identify embryogenic blastomeres.
Hansis
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Program for In Vitro Fertilization, Reproductive Surgery and Infertility, New York University Medical Center, 660 First Ave, 5th floor, New York, NY 10016, USA. ChrHansis@aol.com
Tang
Y X
YX
Grifo
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JA
Krey
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LC
D000818:Animals; D001483:Base Sequence; D001757:Blastomeres / Q000378:metabolism*; D002970:Cleavage Stage, Ovum / Q000166:cytology / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D051379:Mice; D050814:Octamer Transcription Factor-3; D011003:Ploidies; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics*
D017931:DNA Primers; D004268:DNA-Binding Proteins; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; C494174:Pou5f1 protein, mouse; D012333:RNA, Messenger; D014157:Transcription Factors