395 Bulletin UASVM Animal Science and Biotechnologies, 65(1-2)/2008 pISSN 1843-5262; eISSN 1843-536x NEW POSSIBILITIES OF MAMMAL CLONING Vintilă I.*, Ana Claudia Stanca**, B. Cârstea**, Cornelia Vintilă*, Roxana D. Vintila***, Elen Gocza** *USAMVB Timisoara, ** Institute of Agricultural Biotehnologies Godollo-Hungary, ***UMFT Timisoara Key words: mammal cloning, embryonic stem cells, chimeras, lab mice Abstract. Knowing the role of human genes in cell and tissue, economy can't be achieved only if genes of interests are transferred into the genome of animals realizing the humanization of experimental animal models. Because until this moment this can't be achieved only at the beginning of life of the individual, there was the need of creating embryos from cells which genome contained previously transferred genes of interest. In conclusion, in creating and developing cloning methods we have to consider specific methods used in embryology, molecular biology and transgenesis. Pluripotent embryonic stem cells or even adult stem cells can be used not only for realizing transgenesis for genes of interests, but also for their further” transformation” into embryos. INTRODUCTION Finding new ways of mammal cloning would help us very much understanding the role of each human gene in the cell and tissue structure and function, on one side, and would make a huge step in animal science efficiency. Many methods have been already tried in order to solve this issue. Preimplanational embryo blastomeres totipotency has suggested the idea that their repeated dissociation from morulas and their separate „in vitro” cultivation could become a way of mammal cloning. Experiments performed by Willadsen et al (4) demonstrated that this is possible until the stage of 4-8 cells. Because these are losing stepwise their totipotency, this method of cloning stays valable until the embryo reaches 4-8 blastomeres. Embryonic bisection in the stage of blastocyst and their transfer, after a previous cultivation of few hours in the thermostat, into the uterine corns of foster mothers, reproductively synchronous with the embryonic age, has constituted a remarkable progress in domestic animal cloning progress, applicable even in bull farms in order to obtain identical twins (1). Embryonic nuclear transfer or transfer of primitive somatic cells (fibroblasts) or specialized cells (mammary cells) and their cultivation in the vitellus of enucleated oocytes has constituted the third generation of methods in which farm animal cloning has been tried. This method was successfully applied both in sheep cloning (sheep Dolly and Polly), as well as in bull cloning and other mammal species (2, 3, 1). In our work we will describe a method used by our team to obtain lab mice from embryonic stem cells. Because until this moment, embryonic stem cells can be achieved from mice, humans, sanguine monkey and bovines (cells similar to embryonic stem cells), it is reasonable to say that this method can be used in animal cloning.