|「Early mammalian lineages and stem cell lines」
|Jennifer Nichols 先生
MRC Human Genetics Unit, Institute of Genetics and Cancer,
University of Edinburgh, UK
〈 演題要旨 〉
To enable implantation in the uterus, mammalian embryos form blastocysts comprising trophectoderm surrounding epiblast and hypoblast. The mode of implantation varies considerably between species. Mouse embryos are initially cushioned by thick deciduum, whereas human blastocysts attach directly to the uterine wall via polar trophectoderm. We observed multi-layering of human trophectoderm before implantation, presumably required for rapid invasion to secure the developing embryo and initiate formation of the placenta. We used sequential fluorescent labelling to investigate the source of the extra trophectoderm. Preliminary results implicate that division and inward displacement from the polar region contributes substantially to trophoblast thickening. Interestingly, some embryos donated to our project exhibit disproportionate growth of trophoblast. We hypothesise that these represent embryos in which the rapid proliferation has become out of control and that such structures may implant, but either fail to develop or cause molar pregnancies. In mouse embryos or embryonic stem cells ectopic trophoblast formation requires Oct4 deletion. We recently showed that in Oct4 null mouse embryos Stat3 signalling is the most significant pluripotency-associated pathway to be affected during the transition to trophoblast, but it remains to be determined if a similar mechanism exists in the context of human naïve pluripotency.