Mechanics of Embryonic Self-Organization and Plasticity – Embryonics
Mechanics of embryonic development
Characterization of the mechanical forces at play during the self-organized development of the vertebrate embryo
Characterization of the mechanical forces at play during the self-organized development of the vertebrate embryo
How molecular and mechanical cues interplay to coordinate the morphogenesis and cell differentiation during development is still largely unknown. This is largely due to the lack of approaches to probe the mechanics (forces involved and mechanical properties) of embryonic tissues. The avian embryo, which exhibits a highly regulated development and lends itself very well to dynamic imaging approaches as well as to mechanical perturbations, constitutes an ideal model for the study of such interactions. This project, by integrating experiments and theory, aimed to measure the mechanical forces and tissue material properties (elastic and/or viscous) that dictate the shape of the early embryo. To this end, we have developed a micromanipulator that can both measure and apply physical forces by interacting with the embryonic tissue. The development of such an approach characterizing the embryo from a physical point of view is the first step in the elucidation of the role of mechanical forces in cell fate acquisition. Eventually, these studies will reveal different levels of interaction between cellular, molecular and mechanical signals ensuring the robust, yet plastic, specification and assignment of cell fate.
To measure the forces that shape the embryo and its mechanical properties (i.e. the properties that dictate the deformation of tissues in response to these forces), it is necessary to interact in a controlled manner and in real time with the developing embryo. We have therefore built a motorized micromanipulator that allows us to come in contact with the embryo while its development is monitored in real time by video-microscopy. The development of this micromanipulator required to adapt to the constraints related to the culture of the embryo but also to those related to its imaging. Moreover, we have set up an image analysis and biophysical modeling system allowing us to extract physical quantities from the films obtained during the experiments.
The development of this approach (micromanipulator and biophysical analysis) allowed us to measure in absolute values the forces, elasticity and viscosity of the early embryo and thus to approach the formation of the embryo from a biophysical point of view. Our results indicate that the embryo behaves as an elastic material over short times (seconds, minutes), and as a fluid material over long times (tens of minutes).
These results will allow us to explore the cellular events underlying the elasticity and viscosity of the tissue or to apply controlled mechanical perturbations and observe the effects on the development of the embryo. These are areas of research that we are currently pursuing.
This approach, experimental and conceptual, will allow both the mapping and perturbation of the mechanical forces and material properties of the different embryonic territories that make up the early embryo, paving the way to understanding how mechanical and molecular signals interact to allow the emergence of cell fate, during embryonic self-organization.
- One publication in progress.
- One review on the role of mechanical force in patterning has been published: P.-F. Lenne et al., Phys Biol. 18 (2021), doi:10.1088/1478-3975/abd0db
How molecular and mechanical cues combine to coordinate the morphogenesis and patterning of embryonic structures is an open question in the field of developmental biology. The early avian embryo is an ideal model for the study of this interplay as it exhibits highly regulative development, is greatly amenable to live imaging approaches, and can be readily mechanically challenged. We have recently characterized the mechanical forces that shape the early avian embryo, identifying a tensile ring, at the margin between the embryonic and extra-embryonic territories, as the driver of morphogenetic movements within the embryonic disk. These findings suggest that mechanical stresses transmitted along the embryo margin and throughout the surrounding tissue could function as signals in embryonic regulation and in the establishment of embryonic territories. To pursue this hypothesis, we propose, through a tight integration of experiments and theory, to i) test whether a mechanical self-organizing system underlies the remarkable regulative potential of the early avian embryo; ii) elucidate the role of mechanical forces in cell fate specification. These studies will decipher the interplay between cellular, molecular, and mechanical cues that ensures the robust, yet plastic, specification and allocation of cell fate.
Project coordination
Jerome GROS (INSTITUT PASTEUR)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
Partnership
LPENS Laboratoire de physique de l'ENS
IP INSTITUT PASTEUR
Help of the ANR 130,680 euros
Beginning and duration of the scientific project:
March 2020
- 48 Months
