Morphologies of compressed active epithelial monolayers.

Area of Science:

• Biophysics
• Developmental Biology
• Computational Biology

Background:

• Epithelial tissues form complex structures crucial for organ function.
• Understanding the physical forces driving tissue morphogenesis is key to developmental biology.
• Active processes, like myosin dynamics, are known to influence cell and tissue mechanics.

Purpose of the Study:

• To investigate the role of active junctional noise and mechanical strain in shaping epithelial monolayers.
• To determine the conditions under which villus-like structures form in unsupported epithelia.
• To explore the relationship between tissue fluidization, strain, and emergent morphologies.

Main Methods:

• Numerical simulations using a three-dimensional active vertex model.
• Analysis of epithelial monolayers under various in-plane compressive strain conditions (uniaxial, biaxial, isotropic).
• Inclusion of active junctional noise representing myosin dynamics and stochastic binding/unbinding.

Main Results:

• Compressive strains induce distinct fold patterns: longitudinal, herringbone, and labyrinthine.
• Villus morphology emerges when junctional tension fluctuations are sufficiently high to fluidize the epithelium.
• Fluidized epithelia form villi even without compressive strain if apico-basal surface tension is significant.
• Tissue thickness modulation across folds and the role of strain rate were analyzed.

Conclusions:

• Active junctional noise and tissue fluidization are critical for generating complex epithelial morphologies like villi.
• Epithelial tissues can develop intricate structures independent of external patterning or significant compressive forces.
• The findings provide insights into the physical mechanisms governing tissue morphogenesis and the potential for self-organization.