The Cryodamage To The Further Growth And Cell Numbers In Mice Frozen-thawed Embryos

Background Embryo cryopreservation is a well estabilished technique in most in-vitro fertilization embryo transfer(IVF-ET)clinics. It allows for storage and later transfer of supernumerary embryos obtained from IVF treatment. It can indeed achieve the high cumulative pregnancy rates and decrease the expenses of the patients. But compared with the fresh embryos,the implatation rates of cryopreservation embryo is yet low. And it is well-recognized that the cryodamage influence the embryo's survival rates and pregnancy rates , the concrete causes have been researching. Some scholars think that it is not all frozen embyos having the properties to persist with the ultralow temperature,the better the embryos further develop, the stronger their resistant abilities are,so the survival rates and the pregnancy rates will high, vice versa. Others consider that the cryodamage has nothing to do with the cryopreservation per se,but with the cell lysis during the frozen-thawed. If the cryodamage exists,the survival rates and the implantation rates will be decreased.Objective The present study firstly examines the influence of blastomeres lost after thawing on subsequent preimplantation development in vitro by means of the mouse 4-cell and 8-cell embryos. Then compares with the development between the fresh and thawed embryos(including fully intact and≤50% patially intact embryos). At last,the total cell number of the expanded blastocysts are observed.Method The 4-cell mouse embryos(group 1) after 60 hours of injecting the HCG and 8-cell ones(group 2) after 68 hours with no more than 50% anucleate fragment are further divided into the test group and the control group. The test group,is the frozen group including the fully intact...