Athanasios Lontos, PhD student
University Joseph Fourier, Grenoble, France
laboratory TIMC-IMAG, team CAMI (GMCAO)

3D biomechanical simulation of the gastrulation/invagination process

The process of gastrulation is an important early stage of embryogenesis. It is a very complex procedure, during which the organs of the foetus take their initial shape. It is controled by genetic, chemical and mechanical factors, but the precise contribution of each one of them, is still unknown.

Invagination is the initial step of gastrulation. During this stage, the cells are partly guided by chemotaxis, in order to supply their energy demand. It has been observed that some cells start to take the shape of a bottle (bottle-cells), decreasing the surface of their interface with the nourishment fluid. As a result of this surface reduction, the neighboring cells are pulled toward the bottle cells. This results in the blastula performing an inner folding to finally "surround" the nourishment.

The movement of cells during gastrulation is seriously impacted by the centrosome, the cadherins and the cytoskeleton. They are inner-cell structures composed essentially by proteins. More specifically, the centrosome in animal cells is made of two orthogonally arranged centrioles surrounded by proteins. The understanding of the effect of these structures on cell behavior, is a crucial step towards explaining the entire procedure of embryogenesis.

We propose an approach of the phenomenon of invagination based exclusively on the laws of physics and mechanics. For this purpose, we have created a three-dimensional biomechanical model and attempted to simulate the initiation of the procedure of invagination.

Three videos showing the obtained geometry of the area of the embryo where the invagination begins:

The structure from a top point of view

The structure from a side point of view

The structure from a bottom point of view

Video of the contraction of an individual cell located at the flat area:

Cell contraction

Instances of the simulation

Four videos showing the deformation of the whole blastula:

from a top point of view

from a 45 degrees point of view

from a side point of view

from an inside point of view

Three videos of the model of the invaginating blastula based on the Finite Element Method:

from a dorsoventral point of view

from an anteroposterior point of view

and a video of an invaginating cell located at the medial apical cortex of the blastula:

individual cell