[Initial experience with cryopreservation of human embryos]. / První zkusenosti s kryokonzervací lidských embryí.

We present our first experience with human embryo cryopreservation. In our hands the best results were obtained with cryopreservation of pronuclear-staged embryos using propanediol as cryoprotectant. In this group 3 embryos out of 4 continued their development after thawing. The advantages of embryo cryopreservation in IVF programs are discussed.

[Developmental capacity of human embryos after cryopreservation in the unicellular zygote stage]. / Vývojová zpusobilost lidských embryí po kryokonzervaci ve stadiu jednobunecné zygoty.

This study deals with the developmental competence of human embryos after cryopreservation at the one-cell stage using propanediol as cryoprotectant. From 11 frozen zygotes, nine underwent cleavage after thawing. The occurrence of multinuclear blastomeres was the most frequent abnormality which, however, can often be observed in fresh embryos as well. The results of an ultrastructural analysis of the developing frozen-thawed embryos, with special attention to markers of embryonic genome expression, did not show any noticeable impairment of the developmental competence of these embryos as compared with parameters previously described for unfrozen embryos. The findings are discussed with particular reference to current freezing policies in human in-vitro fertilization programmes.