Scientists use cellular programming to mimic first days of embryonic development

The earliest days after fertilization, once a sperm cell meets an egg, are shrouded in scientific mystery. The process of how a humble single cell becomes an organism fascinates scientists across disciplines. For some animals, the entire process of cellular multiplication, generation of specialized cells, and their organization into an ordered multicellular embryo takes place in the protective environment of the uterus, making direct observation and studies challenging.