Patient's question:
Because I have been unable to get pregnant, I am currently undergoing in vitro fertilization. However, during the egg retrieval, the doctor found there were 7 embryos, but the doctor also mentioned there was one blastocyst. What is a blastocyst?Doctor's answer:
A blastocyst is a type of embryo and represents the final stage of in vitro embryo culture. After sperm and egg combine to form a zygote, the zygote begins to undergo cell division. By the third day after fertilization, the zygote typically develops into a cleavage-stage embryo, which has 6-8 cells. Around the fifth day, the zygote further develops into a blastocyst-stage embryo. The blastocyst has a larger number of cells, generally dozens or even hundreds. The cell cluster differentiates into trophoblast cells and the inner cell mass. The embryo contains a cavity, appearing as an empty sac, hence the name "blastocyst."