Stress ball morphogenesis: How the lizard builds its lung.

Area of Science:

• Comparative anatomy
• Developmental biology
• Biophysics

Background:

• Vertebrate lung function is linked to structural anatomy, which shows significant variation.
• Lizard lungs possess a cavernous lumen and honeycomb-shaped wall, suggesting complex airflow despite architectural simplicity.

Purpose of the Study:

• To elucidate the physical principles governing the self-assembly of the lizard lung's honeycomb architecture.
• To understand the interplay between fluid pressure, epithelial topology, and muscle mesh formation in lung development.

Main Methods:

• Transcriptomics and time-lapse imaging to study hexagonal meshwork self-assembly.
• Computational modeling to predict pressure-driven epithelial topology changes.
• Optogenetically driven contraction of 3D-printed engineered muscle to probe model predictions.

Main Results:

• The lizard lung wall forms from a smooth epithelial sheet pushed through a hexagonal smooth muscle mesh by fluid pressure.
• The hexagonal muscle mesh self-assembles in response to mechanical stresses (circumferential and axial) generated by fluid pressure.
• Computational models accurately predicted pressure-induced topological changes, validated by experiments with engineered muscle.

Conclusions:

• The study reveals the physical mechanisms, driven by fluid pressure and self-assembling muscle networks, that sculpt the unique honeycomb structure of lizard lungs.
• These findings offer insights into developmental processes and suggest potential strategies for bioengineering artificial tissues with complex architectures.