Control of Modular Tissue Flows Shaping the Embryo in Avian Gastrulation.

Area of Science:

• Developmental Biology
• Cellular Dynamics
• Biophysics

Background:

• Avian gastrulation involves complex cell movements to establish the body plan.
• The Dynamic Morphoskeleton (DM), comprising attractors and repellers, governs these flows.
• The origins of repellers and their role in embryonic shape changes were previously unclear.

Purpose of the Study:

• To elucidate the mechanistic origins of repellers in the avian Dynamic Morphoskeleton (DM).
• To understand the role of repellers in shaping embryonic development and cell flow dynamics.
• To investigate the modularity of gastrulation flows and their underlying physical principles.

Main Methods:

• Active matter physics principles were applied to model cell flow dynamics.
• Experimental manipulations in chick embryos were used to test theoretical predictions.
• Inhibition of mesendoderm induction and mechanical confinement were employed to alter repeller activity.

Main Results:

• Repeller 1 arises from the interplay between extraembryonic epiboly and embryonic active stress.
• Repeller 2 originates from myosin-driven intercalation in the mesendoderm, influencing embryo shape.
• Experimental perturbations successfully eliminated repellers, validating the model's predictions.

Conclusions:

• Avian gastrulation flows exhibit modularity, governed by distinct physical mechanisms.
• The study uncovers the roles of extraembryonic epiboly, embryonic active constriction, and mesendoderm dynamics in gastrulation.
• Findings provide insights into synthetic morphogenesis and deconstructing complex developmental processes.