Shape and size changes of adherent elastic epithelia

Area of Science:

• Biophysics
• Developmental Biology
• Cell Biology

Background:

• Epithelial tissues are crucial for development and embryogenesis.
• Existing 2D models of epithelial tissues lack key features like apical-basal polarity, variable thickness, and active, non-equilibrium properties.

Purpose of the Study:

• To develop a minimal continuum model of planar epithelial tissue as an active elastic material.
• To incorporate apical-basal polarity, variable cellular thickness, and active nature into a 2D model derived from 3D principles.
• To explain how active stresses and torques drive tissue shape changes and morphogenetic events.

Main Methods:

• Development of a minimal continuum model for planar epithelial tissue.
• Derivation of an effective 2D model from a 3D description, incorporating apical surface curvature.
• Identification of four distinct sources of active stresses and tensions.

Main Results:

• The model captures apical-basal asymmetry and spatial geometry through apical surface curvature.
• Active stresses across the apical-basal axis generate active torques, driving curvature transitions.
• Competition between bulk active stresses (actomyosin contractility, growth) and boundary active tensions (cables, lamellipodia) generates diverse epithelial states.

Conclusions:

• The model unifies 3D shape deformations via coupled apical curvature and in-plane tissue mechanics.
• Results provide insights into tissue folding and lumen formation during early development.
• The framework explains the morphospace of planar epithelia through active mechanics.