EN
The development of non-surgical methods of embryo collection and transfer, primarily in cattle, has led to the commercialization of these techniques, including the production of genetically identical twins. The aim of this paper is to review the progress of the studies on the production of monogenetic progeny using microsurgical bisection of embryos, with a special emphasis put on factors affecting the efficiency of this method. We have also described our new alternative method of monogenetic twin production in cattle based on modified bisection of specifically hatching blastocysts, whose zona pellucida had been perforated.