Reconstruction of mouse embryos was performed by injection of donor genetic material from differentiated cells of various types (cumulus cells, cardiomyocytes, and epithelial cells) into recipient cells (mature oocytes and zygotes). A medium for microsurgery was selected, which enhanced survival of both embryonic and somatic cells during the reconstructive manipulations. Special preparation of somatic cells to transplantation was carried out, which employed factors synchronizing the cells in a certain phase of the cell cycle in order to enhance their capacity to maintain the development of reconstructed embryos. The processes of nucleus reprogramming in specialized cells under the action of cytoplasmic factors of oocytes and zygotes were examined. During in vitro culturing of reconstructed embryos, the most successful development was observed in embryos implanted with donor material from cumulus cells. Mouse embryos reconstructed with a certain genome and subsequent production and use of stem cells are considered as the model system for developing the basic principles of replacement therapy.