Preparation of pregnancy knowledge (7)

Q: why did I take 12 eggs in a test tube and end up with only seven embryos?

A: the eggs obtained first are not always fully mature, only mature eggs can be fertilized; Secondly, not all of them can complete cleavage and develop into embryo after fertilization. Third, even if the eggs are fertilized and split, the resulting embryos are of mixed quality, and only embryos of good quality can be transplanted and frozen, so it's not as if there are as many eggs as there are embryos.