Embryo-scale epithelial buckling forms a propagating furrow that initiates gastrulation

Area of Science:

• Developmental Biology
• Biophysics
• Computational Biology

Background:

• Cell apical constriction, driven by actomyosin forces, is key in embryonic tissue folding.
• The necessity and sufficiency of these forces for driving tissue folding remain unclear.
• Previous models suggested cell-specific forces, not just apical constriction, are needed for tissue furrowing.

Purpose of the Study:

• To investigate whether apical actomyosin contraction forces are necessary and sufficient for driving tissue folding.
• To challenge the prevailing hypothesis that active or passive cell apico-basal forces are required for cell wedging and tissue furrowing.

Main Methods:

• Utilized the Drosophila embryo model system.
• Employed 3D computational modeling.
• Performed in toto embryo image analysis and manipulation.

Main Results:

• Demonstrated that embryo-scale force balance at the tissue surface is necessary and sufficient for tissue folding.
• Showed that epithelial surface buckling initiates furrow formation.
• Challenged the idea that cell-autonomous shape changes are the primary drivers of tissue furrowing.

Conclusions:

• Embryo-scale force balance, not individual cell shape changes, drives tissue folding and gastrulation.
• Epithelial buckling is the critical event initiating furrow formation and mesoderm internalization.
• This finding redefines the understanding of the forces governing early embryonic morphogenesis.