Comparison of Cryoprotectants and Stages of Human Embryo

Human embryos can be cryopreserved successfully by protocols using 1,2 propanediol (PROH), dimethylsulfoxyde (DMSO) or glycerol as cryoprotective agents. Each of these cryoprotectants give the optimal efficacy when used at a defined stage of embryo development, namely pronucleated or early cleavage (PROH), cleavage (DMSO) and blastocyst (glycerol). The aim of the present paper was firstly to review the success rates of each protocol from the data published by different teams. We wish also to present results obtained in Clamart using PROH for cryopreservation of 1- or 2-day embryos and to analyze the influence of several factors on these results.