Filimonow Katarzyna, Chołoniewska Anna, Chołoniewski Jan, Madeja Zofia E, Barłowska Katarzyna, Grabarek Joanna, Wenta-Muchalska Elżbieta, Plusa Berenika, Piliszek Anna
Department of Experimental Embryology, Institute of Genetics and Animal Biotechnology, Polish Academy of Sciences, Postępu 36A, 05-552 Jastrzębiec n/Warsaw, Poland.
Department of Neurogenetics and Functional Genomics, Mossakowski Medical Research Institute, Polish Academy of Sciences, 5 Pawinskiego Str, 02-106 Warsaw, Poland.
Biol Reprod. 2025 Jul 22. doi: 10.1093/biolre/ioaf157.
In the course of mammalian development, the initial state of totipotency must be lost to allow the acquisition of specific cell fates. The first differentiation event results in the formation of trophectoderm (TE) and the inner cell mass (ICM). In the mouse embryo, the cell fate of these two compartments is set quickly after blastocyst formation. However, recent reports suggest that the plasticity of these two lineages might be extended in species other than the mouse. Here, we investigated how the cellular plasticity of early mammalian embryos relates to developmental time scale and changes in gene expression using rabbit isolated ICMs. We studied the dynamics of rabbit blastocyst formation using time-lapse imaging and identified GATA3 as an early marker of rabbit TE and CDX2 as a marker of fully formed TE. We then analysed the developmental potential of rabbit ICMs isolated by immunosurgery and subsequently cultured in vitro. ICMs originating from early- to mid-blastocyst stage embryos are able to re-form a blastocyst-like structure, with a functional TE, and an ICM containing both SOX2-positive epiblast cells and SOX17-positive primitive endoderm cells. We further observed that rabbit ICMs isolated from later blastocyst stages lose the ability for TE specification, instead forming a halo-like cavity with an outer layer of SOX17-positive cells. Our data indicate that in mammalian embryos, the potential for TE differentiation gives way to the formation of a different type of extraembryonic epithelial layer, suggesting a potential common mechanism of pluripotency restriction between eutherian mammals.
在哺乳动物发育过程中，全能性的初始状态必须丧失，以便获得特定的细胞命运。第一次分化事件导致滋养外胚层（TE）和内细胞团（ICM）的形成。在小鼠胚胎中，这两个部分的细胞命运在囊胚形成后很快就确定了。然而，最近的报告表明，这两个谱系的可塑性可能在小鼠以外的物种中得到扩展。在这里，我们使用兔分离的内细胞团研究了早期哺乳动物胚胎的细胞可塑性与发育时间尺度以及基因表达变化之间的关系。我们使用延时成像研究了兔囊胚形成的动态过程，并确定GATA3为兔滋养外胚层的早期标志物，CDX2为完全形成的滋养外胚层的标志物。然后，我们分析了通过免疫手术分离并随后在体外培养的兔内细胞团的发育潜力。源自早期至中期囊胚阶段胚胎的内细胞团能够重新形成类似囊胚的结构，具有功能性的滋养外胚层，以及一个包含SOX2阳性上胚层细胞和SOX17阳性原始内胚层细胞的内细胞团。我们进一步观察到，从后期囊胚阶段分离的兔内细胞团失去了形成滋养外胚层的能力，而是形成了一个类似晕圈的腔，其外层为SOX17阳性细胞。我们的数据表明，在哺乳动物胚胎中，滋养外胚层分化的潜力让位于形成一种不同类型的胚外上皮层，这表明真兽类哺乳动物之间存在多能性限制的潜在共同机制。
