Obtainment of chimeric blastocysts of mice by methods of laser nanosurgery

The procedure of obtainment of chimeric blastocysts of mice by laser nanosurgery methods with� out using any other techniques is described. To perform the experiments, a special laser micromanipulator was invented. The murine embryonic stem cells (ESC), which were transformed with pEFGFP vector, encoding the green fluorescent protein, were used in the experiments. ESC were introduced into the perivi� telline space of murine embryos at the stage of 8 cells using the laser micromanipulator. The operated embryos were cultured in vitro until the stage of emergence from zona pellucida. The fluorescence and its precise local� ization were registered using a confocal microscope. It was shown for the first time that the inclusions of ESC introduced with the lased micromanipulator were found not only in the inner cell mass (ICM) but also in the trophectoderm of the chimeric blastocyst. The technology of nanosurgical operations at early stage preim� planted mammalian embryos using laser techniques opens great opportunities not only for solution of funda� mental tasks of experimental embryology of mammals but also for obtainment of chimeric and transgenic animals with predetermined genotype.