Anatomy

Physics

Mathematics

Mechanics

Biology

Gene

Biophysics

Induced pluripotent stem cell

Embryonic stem cell

Gastrulation

Mathematical analysis

Germ layer

Mesoscopic physics

Chemistry

Embryo

Geometry

Vertebrate

Quantum mechanics

Amniote

Primitive streak

Embryogenesis

Cell biology

Traveling wave

Morphogenesis

Biochemistry

Science

Tissue morphogenesis is driven by local cellular deformations that are powered by contractile actomyosin networks. How localized forces are transmitted across tissues to shape them at a mesoscopic scale is still unclear. Analyzing gastrulation in entire avian embryos, we show that it is driven by the graded contraction of a large-scale supracellular actomyosin ring at the margin between the embryonic and extraembryonic territories. The propagation of these forces is enabled by a fluid-like response of the epithelial embryonic disk, which depends on cell division. A simple model of fluid motion entrained by a tensile ring quantitatively captures the vortex-like "polonaise" movements that accompany the formation of the primitive streak. The geometry of the early embryo thus arises from the transmission of active forces generated along its boundary.

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