Day 5 or 6 blastocysts grow in culture and expand over time. Before the cryopreservation procedure takes place they have to shrink allowing the fluid inside the blastocyst to come out. The extraction of this fluid before cryopreservation has demonstrated to favor embryo survival. This minimizes embryo damage avoiding the formation of ice crystals inside the embryo. The video shows how the blastocysts shrink after a laser shot performed using a microscope at 400X magnification.