[Programmed pre-embryonic freezing in the pronuclear stage]

The authors discuss about freezing procedure of surplus pronuclear stage praeembryos in six cases. The total amount of praeembryos were 36. From these nine were thawing and were cultured further. The surviving rate was 88.8%, the development to blastocysts rate was 77.7%. The freezing procedure in pronuclear stage needs some extra methodological force. The success, increasing influence on pregnancy rate and the benefit that reduces the IVF-ET patient's intolerance procedure is also an important factor. Beneath the cost saving effect of this intervention, the cryopreservation technique for the institutes performing this way of assisted reproduction is highly suggested.