French Flag Morphogenetic Gradient

Wolpert positional information model vs Turing reaction-diffusion patterning

Gradient Parameters

∂c/∂t = D∇²c − kc
Steady: c(x) = S·e^(−x/λ), λ=√(D/k)
Decay length λ = 0.000
Blue width = 0%
Mode: Wolpert gradient
Wolpert (1969): cells read positional information from a morphogen gradient and adopt fates by threshold comparison. Turing mode shows spontaneous pattern formation from two interacting species (activator-inhibitor).

Blue fate (high conc.) White fate (mid) Red fate (low)

Morphogen Concentration Profile

Cell Fate Pattern (1D tissue row)

Reaction-Diffusion (Turing) Activator Field