FIGURE 1.

Schematic illustration of the SCNT process. Somatic cells from the desired donor mammal are cultured for SCNT. Oocytes are recovered from the ovaries obtained from the slaughterhouse and allowed to mature into metaphase (M)II oocytes. MII oocytes are enucleated, and donor somatic cells are transferred into the perivitelline space of oocytes. After the fusion and activation of cell–cytoplast complexes, the reconstructed cloned embryos begin to develop, undergoing nuclear condensation and nuclear swelling, followed by pseudo-pronucleus, 2-cell, 4-cell, etc. stages and form blastocysts in vitro. Cloned embryos are transferred into surrogates and develop into cloned mammals.