最初の胎盤が光ったキメラの免染はExtended Data Figure1-b,cだね。これしか
論文には無いからね。Yolk sac は小保方さんの語彙選択の間違いで、笹井さんが
本文で使っている fetal membranes が正しいね。
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Surprisingly, injected STAP cells contributed not only to the embryo but also to the placenta and fetal membranes (Fig. 1b and Extended Data Fig. 1a–c) in 60% of the chimaeric embryos (Fig. 1c).
yolk sacという言葉は
①Figure1-cのブルーの四角の説明にEmbryo+placenta+yolk sac
②同上リジェンドにc, Percentages of fetuses in which injected cells contributed only to the embryonic portion (red) or also to placental and yolk sac tissues (blue). ***P < 0.001 with Fisher’s exact test.
③Extended Data Figure1-bの写真の上2枚のキャプチャーにYolk sac
④同上cの写真のタイトルにSTAP chimaeric yolk sac
⑤同上リジェンドのすべてにa, Chimaeric mouse with STAP cells derived from CD45+ cells of B6GFP × 129/Sv mice (B6GFP, C57BL/6 line with cag-gfp transgene). Arrows indicate a placenta and a yolk sac. b, Cross-sections of yolk sac (top) and placenta (bottom). GFP-positive cells (arrows) were seen only in yolk sac and placenta of the STAP cell chimaera. Scale bars, 50 μm. c, Co-immunostaining showed that these GFP-positive cells (right) were found in the extra-embryonic endoderm-derived epithelial cells (pan-cytokeratin+ and overlying laminin+ basement membrane; left) of the yolk sac. Scale bar, 10 μm.
もう少し先まで引用しとこうかしらね。
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#12 Peer 5 commented 5 years ago
The authors claim that "Surprisingly, injected STAP cells contributed not only to the embryo but also to the placenta and fetal membranes (Fig. 1b and Extended Data Fig. 1a??"c) in 60% of the chimaeric embryos (Fig. 1c)." and they show the analysis of chimaeric embryos with placentas at E12.5. I'm sorry to say but that is normal in E12.5 chimaeric embryos produced by injection of wt ES cells into blastocyst, since the placental FETAL blood vessels and yolk sac mesoderm cells are derived from the ES-cell derived epiblast. For a wide explanation of the different ways of making chimaeras and developmental limitations of cells in chimaeras and contributions you can consult the book "Mouse phenotypes: a Handbook of mutation analysis" Cold Spring Harbor Press. Chapter 8, in specific Box 8.3.
In that sense what is surprising to me is that in their chimaeras (fig 1a and 1c) produced by injection of GFP expressing ES cells (Rosa26GFP or CAG-GFP) into blastocyst none showed fluorescence in the placenta (fetal blood vessels) or yolk sac (yolk sac mesoderm). The extent of GFP depends on how good the chimaeras were. I would expect that a chimaera like the one they show in figure 1a should have a great amount of GFP positive cells in the placental and yolk sac fetal blood vessels (mesoderm=GFP). I really find hard to explain how in 50 out of 50 control chimaeras they just found "embryo specific" contribution of ES cells without contribution to extraembryonic mesoderm.
One possibility is that if the wt ES cells used in their work had a reduced pluripotency as a consequence of bad karyotype or bad culture conditions, that would produce low chimaerism (bad chimaeras) and the contribution of GFP positive ES-derived cells to extraembryonic mesoderm would in consequence be reduced. I predict that if they had looked more carefully their ES-cell derived chimaeras, they would find the normal contribution of ES cells to the extraembryonic mesoderm in the placenta and yolk sac.
A big complication of doing their analysis in chimaeric embryos between E9-E12.5 (stages shown in their figures) is that the supposed contribution of STAP cells to the trophoblast in the placenta and yolk sac could have been mistaken due to the presence of GFP-positive extraembryonic mesoderm. To solve this complication they should have used a bigger combination of molecular markers and lineage tracing experiments to prove that STAPs differentiated into trophoblast derivatives or visceral endoderm cells in vivo. Convincing demonstration of STAPs differentiation into these cell types in vivo was not achieved in my opinion.
