[Hox-cluster and evolution of morphogeneses].

Comparative studies of genomes of lower Metazoa showed that many classes of transcription factors important for the development of bilateral animals appeared before the divergence of modem branches of the animal kingdom. The genes of the Hox-cluster appeared late, in the last common ancestor of Cnidaria and Bilateria. Structural expansion and perfection of mechanisms which integrate the Hox-cluster can be traced in the morphogenesis of modern bilateral animals. It is now evident that different strategies of using this regulator instrument led Bilateria to absolute domination in number and diversity of species among all Metazoa animals.