Abstract

The morphogenesis of embryos has been fascinating biologists, physicists, and mathematicians since the beginning 19th century. Yet, the precise physical principles governing the shape and dynamics of single cells and early embryos remain poorly characterized. Building on tension models of cell’s morphology, I will present here simple physical approaches on two fundamental morphogenetic processes in early embryogenesis: cell division and cell-cell interaction.

In the first part, I will show that cell division can be seen as a first order transition between two stable mechanical states, leading to an experimentally testable hysteresis behavior. I will then present a dynamic model for the cell surface, which can accurately reproduce essential features of cell division in embryos, such as the independence of division time with cell size. Finally, using recent active gel theories for motor-filament systems, I will show that the reorganization of the filamentous structure at the cell surface upon motor activity may play an important mechanical role in cell division.

In a second part, I will describe the physical process of cell positioning in early mammalian embryos. Using a simple cell doublet model, I will show that differences in surface tensions both within and between cells is enough to recapitulate the two first morphogenetic processes in the early mouse embryo: compaction and internalization. I will end up my talk by illustrating these two processes for a realistic 3-dimensional embryo with advanced multicellular numerical simulations.