What is blastocyst culture and transfer?
A blastocyst is an embryo that has developed for 5 to 7 days after fertilization and has just started to differentiate. It has developed two different cell types and a central cavity. One group of cells will become the placenta, and the other group will become the fetus. A healthy blastocyst will begin hatching from its outer shell by the sixth or seventh day. Shortly after hatching from the shell, it should begin to implant into the lining of the mother’s uterus. In past years, the majority of embryo transfers were done on day 3 (after the egg retrieval) at the “cleavage stage” when the embryos have four to eight cells. One problem with this is that day 3 embryos normally are found in the fallopian tubes, not in the uterus. The embryo first moves into the uterus at about 80 hours after ovulation. The embryo implantation process begins about 3 days later, after blastocyst formation and hatching have occurred. The other problem with transferring on day 3 is that many embryos at that sta
