Artificial Shrinkage Method In The Vitrification Of Mouse Blastocyst

Background The slow cooling cryopreservation method for cleaved embryos has been widely used since the first human pregnancy resulted from cryopreserved 4- to 8-cell embryos, as reported in 1983. But time-consuming and laborious are its shortcoming. Vitrification is performed by suspending the embryo(s) in a solution containing a high concentration of cryoprotectants and then directly plunging the embryo(s) into liquid nitrogen. The advantage of this technique is the prevention of ice crystal formation within the embryo tissue or outside the cytoplasm. Several new techniques and applications were developed recently that improve the survival rate and hatching rate following vitrification. These procedures include the use of an electron microscope (EM) grid, cryoloops and an open pulled straw (OPS). These techniques attempt to accelerate the blastocyst cooling rate and decrease the cryosolution volume needed for this procedure. Recently, It reported an increase in the survival rate of blastocysts when the volume of the blastocoele was artificially reduced with a needle. However, this method is invasive because it makes a hole in the zona and trophectoderm. On the other hand, It reported that the blastocoele of expanded blastocysts could be artificially collapsed by mechanical pipetting with a glass pipette slightly smaller in diameter than the blastocyst. This artificial shrinkage method is thought to be non-invasive and useful for vitrification of expanded blastocysts, but the usefulness of this method has not been well documented.Object The study is designed to evaluate the survival rate and...