How to Study Embryos, No Embryo Required

A representation of a blastoid, which is a synthetic embryo formed in the lab, from stem cells. The green cells are the trophoblast stem cells (the future placenta), whereas the red cells are the embryonic stem cells (the future embryo). (Credit: Nicolas Rivron) Studying human development — especially the earliest stages of pregnancy — can be a tricky thing. Usually, scientists need embryos to examine these early stages. The problem is, embryos are an expensive, limited resource and working with them is fraught with ethical dilemmas. Now, a new study in Nature details the development of a synthetic embryo that can help researchers avoid these issues and better understand the earliest days of development.