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The method of vitnilcation has various merits. It needs neither seeding nor slow freezing. It can freeze embryo by putting it directly into liquid nitrogen at the indoor temperature to 0℃. The operation process is quite easy. Moreover, higher promise of survival can be expected as there is no physical damage by any lumps of ice with the exception of cells. In Kasal’’’’s experiment (1990) using EFS liquid and Kang’’’’s experiment (1991) using GFS liquid the ratio of the damaged embryo was only 2-3%. But, the method of vitrification is now on the process of improvement, and the final or united method is not yet established. At the present time, most of the major institutes all over the world are using the traditional freezing method in the preservation of mouse embryo, but it is very likely that the vitrification will prevaIl in the near future considering the various merits of it. Calves can be begotten from the embryo by means of vitriilcated preservation in the cases of cow, rat, and rabbit as well as of mouse. In addition, recent experiments have shown that vitrificated preservation was successful in the case of drosophila embryo which was much bigger than mammalian embryo, which fact tells that this method is expected to be preferably used even in the preservation of living organs in the near future.
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