[Initial results of a cryopreservation program for human ova and embryos].

A human egg and embryo freezing program for non fertilized eggs and spare embryos was established recently in our ib vitro fertilization clinic. The first results are reported. Two cryoprotectants, glycerol and dimethylsulfoxid (DMSO) were used in an automatic computerized freezing program. DMSO gave us better results in terms of a 55% survival of all blastomeres (from 6 normal and 5 pathologic 2- to 16-cell embryos) after thawing. Some of the thawed embryos continued cleavage in vitro. Four embryo replacements were performed with the 6 normal embryos, but none of them resulted in pregnancy. The rapid technique using glycerol gave us less good results in terms of blastomere survival (34%); however, from 3 embryo replacements one "biochemical pregnancy" was obtained from a thawed four-cell embryo. At first attempts to freeze and thaw unfertilized eggs, DMSO seemed also to give better results. The presented cryopreservation techniques which are modifications of those published by Trounson et al. and Zeilmaker et al. need further improvement although the first results are encouraging.