在小鼠胚胎发育早期，外胚层的概念已提出多年。然而到目前为止，外胚层分化和发育的内部机制仍然所知甚少。我们在体内确立了外胚层存在的位置与时期，通过激光显微切割以及单细胞测序等技术，在全基因组水平上考察和分析了外胚层的转录表达图谱。我们进一步考察了外胚层区域的表观遗传修饰与转录组之间的调控关系。同时，在体外建立了外胚层干细胞系。本项目拟在上述研究基础上，结合体内体外的实验手段，继续深入研究原肠运动过程中外胚层命运决定的重要分子机制，在全基因组水平上详细阐释表观遗传调控对外胚层模式建成的影响和分子调控。这些工作的完成将有助于加深人们对胚胎发育早期外胚层细胞谱系的认识，并对外胚层细胞命运决定的分子机制研究和外胚层干细胞的临床应用打下坚实的基础。

Early mammal embryonic development is very important for proper patterning of animal bodies. All the specific tissues and organs are derived from three germ layers which are generated during embryo gastrulation. Ectoderm is one of the three classic germ layers in the early mouse embryo, with the capacity to develop into both the central nervous system and epidermis. Because it is a transient phase of development with few molecular markers, the early ectoderm is the least understood germ layer in mouse embryonic development. In our study, we identified E7.0 as a key developmental stage when ectoderm cells exist transiently in the anterior/proximal domain of the ectodermal layer. Through the combination of laser microdissection and single cell sequencing technology, we analyzed the whole transcriptome of mouse embryo at E7.0. We compared the global transcriptome changes with important epigenetic modifiers and characterized the regulation network directing ectoderm development. Furthermore, the ectoderm cell line was established as an in vitro cell model to study the molecular mechanism underlying the ectoderm lineage commitment. Next, we will carry the analysis in the early and late gastrulation stage. We will construct a temporal and spatial regulation map with high resolution for ectoderm patterning. Based on this findings, we are close to understand the signaling networks and epigenetic regulations that lead to ectoderm identity in very much details. Our study will greatly facilitate the understanding of the ectodermal layer development in early mouse embryos and provide a framework for the ectoderm-based regenerative medicine.