Gradient versus geometrical encoding of information for cell fate decision in early embryogenesis

Cells in embryos need to decode extracellular signals to regulate their genes and eventually acquire the desired fate. In vertebrates, morphogen gradients typically control cell fate inductions, with cells expressing different genes depending on the morphogen concentration they detect. The role of the gradient can also be fulfilled by different contact areas between the cells and the signaling molecules. Cells exposed to the same concentration of signaling molecules can tune the level of signal they receive, and therefore acquire different fates, according to the surface area they expose to the morphogen. We developed minimal conceptual models to compare these two opposite frameworks for cell differentiation. We explored under what conditions, such as system size, cell number, and cell geometry, one mechanism is more efficient than the other in terms of information transmission.