What is an Embryo?

Most scientific and medical advances are accompanied by new terms to describe the new processes. Unfortunately, that has not happened with the new tasks eggs are being asked to perform. As a consequence, the term embryo has been mistakenly applied to all forms of activated eggs, and that is causing rancorous debate. The biology of reproduction provides natural guidelines for when an egg becomes an embryo. Increased public understanding of eggs and embryos will allow the development of appropriate research guidelines.