EDITOR’S CHOICE IN DEVELOPMENTAL BIOLOGY
J. Zenker et al., “Expanding actin rings zipper the mouse embryo for blastocyst formation,” Cell, 173:776–91.e17, 2018.
Not long after egg meets sperm, the resulting mulberry-like mass of cells morphs into a hollow sphere called a blastocyst, sealing itself off from the external environment before implantation. If such sealing doesn’t happen, pregnancy can fail, but “the precise mechanisms that give rise to embryo sealing prior to blastocyst formation remained incompletely understood,” says cell biologist Maté Biro of the University of New South Wales.
Biro and his colleagues used advanced imaging techniques to study live, fully intact mouse embryos as they developed in a Petri dish and found that rings of the protein actin form across the ball of cells and help to zipper the embryo closed in a multistep process. First, microtubules at the outward-facing poles of the cells pull actin proteins into rings that ...
