A tensile ring drives tissue flows to shape the gastrulating amniote embryo

Abstract

Shaping the early amniote embryo 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