Micro-insemination sperm transfer (MIST) and its application to male subfertility: current strategies to improve...

It can be difficult to achieve a pregnancy for patients with severe male factor subfertility. Hence, micro-manipulation techniques, have been applied to this problem. Direct deposition of sperm into the oocyte under the zona (micro-insemination sperm transfer, MIST) has improved the fertilisation rates, but pregnancy rates have been very low. This paper describes the possible new strategies to improve the technique currently. They include methods to improve sperm recovery, to improve acrosome reaction, to improve the quality of embryos by using co-cultures and to wait for good cleavage before transfer, and to improve luteal phase support. There are also many new techniques being developed which may contribute to further pregnancy successes. They include the use of electro-fusion, laser-fusion and the Xenopus cell-free system.