The secret to the longevity of oocytes is in their'self-washing' system. The oocyte (immature precursor of the ovum) has special structures dedicated to capturing and retaining protein aggregates, which are toxic to him.
That is, it has its own self-cleaning system that allows them to live for years. A virus from 500 million years ago is now key in the formation of the embryo. They present the complete model of a human synthetic embryo created in a laboratory.