PRODUCTION OF CHIMERIC MICE FROM CRYOPRESERVED BLASTOCYSTS

Mouse blastocysts derived from in vivo fertilization were cryopreserve d by a simple vitrification method. Most of the cryopreserved blastocy sts survived while demonstrating a normal morphology after warming (88 .1%). The rate of cryopreserved blastocysts which developed to term as normal young was 56.8%, and chimeric mice were also produced from cry opreserved blastocysts injected with ES cells. As a result, 3.4% of th e injected embryos developed to term as germ line chimeric mice.