LAUSR

Developmental Biology Gastrulation is an essential step in development in which the internal tissues of the body are set apart. In birds and mammals, a similar cascade of molecular events is known to specify embryonic territories, but how they are physically remodeled has remained elusive. Working with avian embryos, Saadaoui et al. identified a cable that encircles the embryo as the engine of gastrulation and described the collective cell movements as similar to the motion of a fluid. One side of this contractile ring pulls more strongly than the other, entraining the large-scale tissue movements that shape the early body plan. The embryo margin, previously known to function in molecular regulation, thus emerges as a dual mechanical and molecular organizer of development. Science , this issue p. [453][1] [1]: /lookup/doi/10.1126/science.aaw1965