We studied mixing in the initially separated binary mixture of polystyrene/5CB liquid crystal and ternarymixtures of water/surfactant C12E5/polymer PEG system. In both systems the domains of one phase werecharacterized by a much higher viscosity than the solvent matrix. We demonstrated experimentally that duringmixing these domains decrease their size linearly with time without a visible change of the optical contrast(i.e., without a rapid change of their compositions). Computer simulations and a theoretical model explainquantitatively our experimental observations.