Hydrodynamic simulation of multicellular embryo invagination.

Area of Science:

• Developmental Biology
• Biophysics
• Computational Biology

Background:

• Embryonic morphogenesis, particularly invagination, is crucial for development.
• Previous numerical simulations used finite element models, treating tissue as a continuous medium.
• These models captured global invagination but lacked cellular-level mechanical insights.

Purpose of the Study:

• To develop a novel simulation of multicellular embryo invagination.
• To analyze both cellular and multicellular mechanical behaviors during embryo development.
• To identify minimal structural and force elements sufficient for mesoderm invagination.

Main Methods:

• Developed a simulation model of multicellular embryo invagination.
• Modeled tissue as individual adhesive cells with internal acto-myosin forces.
• Incorporated hydrodynamic flow associated with membrane movements.

Main Results:

• Identified minimal structures: cell membranes with acto-myosin cortical tension and apical/basal junctions.
• A contractile ring connected to apical junctions was also essential.
• A single parameter change—increased apical-cortical surface tension—recapitulated key Drosophila gastrulation shape changes.

Conclusions:

• The model accurately predicts in vivo behaviors like apical junction movements, cell elongation/shortening, and thickness gradients.
• These complex morphogenetic events are passive mechanical consequences of increased apical surface tension.
• The simulation demonstrates accurate structure description at both global and single-cell scales.