Abstract
Nuclear transfer techniques have been known to be useful for producing cloned embryos in animals. This study was designed to examine the ability of the mouse metaphase oocyte cytoplasm to support mitotic cell cycles under the direction of differentiated somatic cell nuclei of various mammalian species. Monkey amniotic epithelial cells, mouse yolk sac cells and fibroblast cells from mouse, pig and rabbit were used as sources of donor nuclei. Nuclear transfer units produced by fusion of enucleated mouse oocytes and individual somatic cells from all species examined underwent transition to interphase accompanied by nuclear swelling, further progression through the cell cycle, and completion of the first mitosis. Regardless of the species of donor somatic cell used, the fusion rate was uniformity. Reconstructed embryos produced by intraspecies nuclear transfer developed to advanced stages, as the evidenced by continuation of cell proliferation and formation of a blastocoele cavity. On the other hands, reconstructed embryos derived from nuclear transfer of interspecies were did not develop over 8-cell stage. These observations suggest that mechanisms regulating early embryonic development may be conserved among mammalian species and that mouse oocyte cytoplasm might be possible to support the introduced differentiated nucleus regardless of chromosome number, species, or age of the nuclear donor.
