Oct-4 expression in inner cell mass and trophectoderm of human blastocysts.
The expression of the transcription factor Oct-4 is thought to be one of the decisive factors that maintain totipotency in embryonic and germ cells. In mice, oct-4 is exclusively expressed in germ cells and totipotent cells of the embryo. In humans, Oct-4 is expressed in germ cells, embryonic stem cells and whole embryos at various stages of development. However, there is limited information about the distribution of Oct-4 expression in human embryos. In an attempt to address this issue, the inner cell mass (ICM) and trophectoderm (TE) of 17 human blastocysts were separated and Oct-4 mRNA expression individually assessed by reverse transcription-polymerase chain reaction (RT-PCR). In discarded blastocysts that developed from two pronuclear zygotes, the mean Oct-4 expression was 31 times higher in totipotent ICM cells than in differentiated TE cells. This finding suggests that, in accordance with data from the mouse, Oct-4 is highly expressed in human ICM cells as opposed to TE cells; this in turn supports the hypothesis that Oct-4 plays a similar role to maintain totipotency in these two species.
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
Grifo
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JA
Krey
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LC
D001755:Blastocyst / Q000166:cytology* / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics*; D004475:Ectoderm / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D050814:Octamer Transcription Factor-3; D016133:Polymerase Chain Reaction / Q000379:methods; D014157:Transcription Factors / Q000235:genetics*; D015053:Zygote
D004268:DNA-Binding Proteins; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; D014157:Transcription Factors