[Cryopreservation of early human embryo stages]

A short review of freezing procedures applied to early human embryos is given. It is noted that human embryos survived freezing and thawing at a developmental stage of 1. cell to blastocyst. But it seems to be necessary to use for any developmental stage of early embryo a special freezing and thawing method. Embryo survival is correlated with their morphologic features where as neither age of embryos nor developmental stage were involved in freezing and thawing ability.