Scaling Law for Epithelial Tissue Rheology

Area of Science:

• Physics of biological systems
• Developmental biology
• Biophysics

Background:

• Epithelial morphogenesis shapes tissues and organs during development.
• Understanding tissue mechanics requires knowledge of active forces and material rheology.
• Rheological properties of embryonic tissues have been difficult to determine.

Purpose of the Study:

• To develop a minimal theory explaining rheological measurements of early fly embryo epithelia.
• To provide a comprehensive explanation of epithelial tissue mechanics.
• To identify the key physical properties governing tissue rheology.

Main Methods:

• Developed a minimal theoretical framework for epithelial mechanics.
• Applied the theory to rheological measurements of the fruit fly (Drosophila melanogaster) embryo epithelium.
• Constrained theoretical parameters using direct experimental measurements.

Main Results:

• The theory explains the observed power-law deformation (exponent 1/2) of embryonic epithelia under pulling force.
• Estimated the spring constant of individual cellular edges.
• Identified stress relaxation (actin turnover), edge elasticity, and network topology as key factors.

Conclusions:

• The minimal theory comprehensively explains epithelial tissue rheology in the early fly embryo.
• Key physical properties governing tissue mechanics on a 1-10 minute timescale have been identified.
• This work advances our understanding of the physics of tissue morphogenesis.