A non-linear reaction-diffusion model of the epigenetic system involvi
ng the synthesis and simultaneous intercellular self and cross-diffusi
on of the activator and inhibitor during embryogenesis has been propos
ed. It has been observed that the system spontaneously emerges into a
stationary dissipative (Turing) structure only in the presence of posi
tive cross-diffusion. That the stationary structure, thus envolved, ha
s been shown to be globally asymptotically stable by using a suitable
Liapunov's function.