Extraembryonic tissues have pivotal roles in morphogenesis and patterning of the early mammalian embryo. Developmental programmes mediated through signalling pathways and gene regulatory networks determine the sequence in which fate determination and lineage commitment of extraembryonic tissues take place, and epigenetic processes allow the memory of cell identity and state to be sustained throughout and beyond embryo development, even extending across generations. In this Review, we discuss the molecular and cellular mechanisms necessary for the different extraembryonic tissues to develop and function, from their initial specification up until the end of gastrulation, when the body plan of the embryo and the anatomical organization of its supporting extraembryonic structures are established. We examine the interaction between extraembryonic and embryonic tissues during early patterning and morphogenesis, and outline how epigenetic memory supports extraembryonic tissue development.

胚外组织在早期哺乳动物胚胎的形态发生和模式化中起着关键作用。通过信号通路和基因调控网络介导的发育计划决定了胚外组织的命运决定和谱系承诺发生的顺序，而表观遗传过程使细胞身份和状态的记忆在整个胚胎发育过程中和之后得以维持，甚至延伸到几代人之间。在这篇综述中，我们讨论了不同胚外组织发育和功能所必需的分子和细胞机制，从它们的初始规格到原肠胚形成结束，此时胚胎的身体计划和其支撑胚外结构的解剖组织已经建立。我们研究了早期模式化和形态发生过程中胚外组织和胚胎组织之间的相互作用，并概述了表观遗传记忆如何支持胚外组织发育。