Effect of Ca2+/Mg2+-free medium on the biopsy procedure for preimplantation genetic diagnosis and further development of human embryos

In this study, the use of Ca2+/Mg2+ -free medium for biopsy of human embryo s at the 4- to 10-cell stage on the third day of development was evaluated, When compared with control medium containing normal concentrations of Ca2 and Mg2+ ions, the use of Ca2+/Mg2+-free medium allows an easier removal o f blastomeres as illustrated by a lower rate of cell lysis as well as by a shorter time needed to perform the procedure. Subsequent embryo development to the blastocyst stage is not affected by the choice of biopsy medium, no t even when embryos are exposed to the medium for 45 min. The use of Ca2+/M g2+-free medium thus allows for an easier biopsy procedure during preimplan tation genetic diagnosis, while it does not result in a loss of development al potential of the embryo to the blastocyst stage.