On the domain structure of shadow matter

The possibility is pointed out that shadow domains, i.e. regions of strong suppression of the density of the ordinary matter as compared to the shadow one, can exist in the framework of E8xE8' superstring theory. For homogeneous gravitational potential on the radiation dominancy stage, streaming of plasma and radiation into the shadow domain influences considerably light element abundances, as well as spectral and spatial properties of the relict radiation. It provides stringent restrictions on the possible parameters of small-scale domain structure of the shadow matter. The existence of shadow domains in scales, larger than the size of cosmological horizon in the period of recombination, would open new interesting possibilities in the description of super-scale structure of the Universe