At gastrulation, mesoderm arises as a migratory germ layer that will participate to both foetal and placental development through region-dependant adaptation of cytoskeleton composition, cell shape and migration mode.
Following fertilization, the pioneering transcription factors GAGA factor (GAF) and Zelda are independently required to reprogram the zygotic genome of Drosophila and activate the first wave of gene expression.
Soon after fertilisation, a critical portion of the embryonic genome is switched on through the actions of maternally inherited Stella, in part through controlling the activation of transposable elements.
ME31B is a general repressor of gene expression in the Drosophila early embryo, repressing translation before the maternal-to-zygotic transition and stimulating mRNA decay after activation of the zygotic genome.
The Notch signaling pathway drives transitions in differentiation capacities during the gradual loss of potency that occurs in the preimplantation mouse embryo before the onset of the first lineage decisions.
Live imaging coupled with cell lineage tracing in chick and mouse embryos reveal that the cardiac regulatory gene Nkx2.5 is also transiently expressed in early extra-cardiac hemogenic angioblasts that migrate to the heart, yolk sac and dorsal aorta.
Lineage specification and commitment are synchronized in the developing trophectoderm lineage of the mouse embryo, but are asynchronous events in the maturing inner cell mass, revealing a window of plasticity in this lineage.