How embryos develop – News from the web

Initially, the embryo of an animal looks like a microscopic hollow sphere. Then, at different stages of its development, invaginations give rise to structures such as the brain and the digestive tract.

Invaginations are folds of a tissue on itself.

The way in which these invaginations are triggered to create the different structures of the body was yet to be confirmed. Biologists agreed that the mechanism that triggers these invaginations is buckling, a lateral deformation of a material subjected to compression.

This explanation has long been a consensus in the scientific community, but it remained complex to prove due to the difficulty of measuring the tiny forces involved.

Prof. Aurélien Roux and his colleagues from the Department of Biochemistry of the Faculty of Sciences of the University of Geneva have just taken up the challenge.

The question at the base of our work is to know how we give shape to a cellular tissue.

Aurelien Roux

To answer this, experts in biological experimentation, analytical theoretical physics and computer simulation participated in this work, the conclusions of which are published in the journal Developmental Cell (New window) (in English).

Already, observation of the development of embryos made it possible to describe several mechanisms that are at work, explain the researchers in a press release published by the University.

One of them is apical constriction, that is, a local curvature of the surface of the embryo under the effect of a coordinated deformation of the cells themselves (their Mountain peak tightens and their base relaxes).

However, this mechanism cannot be the only one responsible for the appearance of intussusception in one of the early stages of the development of the embryo called blastocyst.

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The buckling theory

Biologists have therefore proposed that buckling is the physical mechanism for generating these deep folds.

The phenomenon is the same as when placing a sheet of paper flat and bringing the two opposite edges together: the middle of the sheet rises., explain the researchers.

In the case of embryos, the lateral force comes from the cells which, by proliferating, exert an increasing pressure on the surface, a surface which is moreover confined in a vitelline envelope, admittedly elastic, but which prevents any spatial expansion.

Authors of the works

While the theory of buckling quickly gained consensus, the ability to measure the forces present on the surface of embryos to verify this hypothesis was a real headache for researchers.

It is thanks to the intervention of the three research fields that the researchers succeeded in assembling the pieces.

We were able to demonstrate […] that buckling is a possible mechanism to explain the formation of intussusception in embryos.

Aurelien Roux

Source: Radio-Canada | Science

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