There are three basic approaches that are used for the induction of dedifferentiation of somatic cell nuclei: i/ somatic cell nucleus transfer (SCNT): where nuclei are reprogrammed in the oocyte cytoplasm, ii/ production of heterokaryons: where differentiated cells are fused to embryonic stem cells and iii/ the production of induced pluripotent stem cells by enhanced expression of certain transcription factors (OKSM). SCNT seems be the most efficient method. We suggest that SCNT differs from other two approaches and that the main reason is that the transferred nucleus uses some oocyte nuclear organelles that are integrated into newly formed nuclei. In our project we will track the fate of these organelles and analyze their importance for reprogramming.We will analyze the fate of oocyte nucleoli, nuclear membrane and speckles and some nucleolus associated factors (i.e. telomerase). In conclusion, we suppose that nuclei in SCNT embryos are not simply reprogrammed, rather this dedifferentiation represents a combination of two processes: reprogramming and remodeling.