Rectified random cell motility as a mechanism for embryo elongation

Area of Science:

• Developmental Biology
• Biophysics
• Computational Biology

Background:

• Vertebrate embryonic body formation relies on posterior elongation from the tail bud.
• The presomitic mesoderm (PSM), derived from the tail bud, is crucial for elongation movements.
• PSM cells exhibit an anterior-posterior motility gradient linked to fibroblast growth factor (FGF) degradation.

Purpose of the Study:

• To quantify cell diffusive movements along the PSM motility gradient in chicken embryos.
• To develop and validate a model explaining tissue elongation based on cell motility and confinement.

Main Methods:

• Electroporation of fluorescent reporters into the PSM of chicken embryos.
• Time-lapse imaging to track cell movements.
• Development of microscopic and continuum models for cell motility and tissue extension.

Main Results:

• Quantified cell diffusive movements along the anterior-posterior motility gradient.
• A microscopic model incorporating FGF-induced motility and geometric confinement accurately predicts tissue elongation.
• A macroscopic mechano-chemical model couples FGF activity, cell motility, and tissue rheology, matching experimental observations.

Conclusions:

• FGF signaling and lateral confinement are key mechanisms converting cell addition into oriented movement.
• The study provides a unified model explaining how the tail bud drives vertebrate body elongation.
• Experimental data and theoretical models elucidate the biophysical principles of embryonic growth.