THE IN-VITRO AND IN-VIVO DEVELOPMENTAL POTENTIAL OF FROZEN AND NON-FROZEN BIOPSIED 8-CELL MOUSE EMBRYOS

We investigated the in-vitro and in-vivo development of cryopreserved and non-cryopreserved biopsied 8-cell mouse embryos, from which one to seven blastomeres were removed by micromanipulation. The results clearly indicate that the in-vitro and in-vivo development of biopsied 8-cell mouse embryos depended on the number of blastomeres removed: the more blastomeres removed, the greater the effect. When five, six, or seven blastomeres were removed, fewer blastocysts were formed. Furthermore, when these blastocysts were transferred to pseudopregnant females, no living young were formed, indicating the abnormality of these blastocysts. When up to three blastomeres were removed, there was no significant effect on the rate of in-vitro blastocyst formation. Living young were found even after the biopsy of four blastomeres, and after biopsy of only one or two blastomeres, the same percentage of living young was obtained as in the non-biopsied control embryos. Biopsied 8-cell mouse embryos were frozen and thawed in straws with 1,2-propanediol (1.5 M) and sucrose (0.1 M) with slow-freezing and rapid-thawing protocols. The survival after cryopreservation, dermed as the percentage of embryos with the same number of blastomeres intact as the number of blastomeres before freezing, was excellent and no different from non-biopsied embryos, independent of the number of blastomeres biopsied. Furthermore, cryopreservation had no further impact on the in-vitro and in-vivo development of the biopsied embryos.