Embryo transfer method and apparatus

In a method for thawing and transferring embryos frozen in a volume of a cryoprotective solution containing a cryoprotective agent to a suitable recipient at a synchronized time wherein the cryoprotective solution is diluted in a onestep process, the improvement comprising:

• (a) preparing a premeasured diluent solution for combining with said volume to form a dilution mixture, said diluent solution having a volume effective, when combined with the volume of cryoprotective solution, to reduce the concentration of the cryoprotective agent in solution to a nonharmful level, said diluent solution having a concentration of a nontoxic, nonpermeating compound sufficient to be substantially isosmolal with the cryoprotective solution;
• (b) thawing the volume of cryoprotective agent;
• (c) combining the thawed volume with the premeasured diluent solution to form said dilution mixture;
• (d) allowing sufficient time for dilution to occur;
• and
• (e) delivering said dilution mixture to the recipient where washing of said dilution mixture from said embryo occurs.

A method for storing, thawing and transferring an embryo frozen in a volume of cryoprotective agent comprising:

• (a) freezing said volume containing said embryo in a container containing an effective amount of a diluent solution separated from said volume;
• (b) storing said container at freezing temperatures until such time as transfer is desired;
• (c) thawing said diluent solution and said volume and combining said diluent solution with said volume of cryoprotective agent to effect dilution of said agent;
• and
• (d) transferring the contents of said container to the recipient.