In the twentieth and early twenty-first centuries, Gail Roberta Martin specialized in biochemistry and embryology, more specifically cellular communication and the development of organs. In 1981, she named any cell taken from inside a human embryo at the blastocyst stage an embryonic stem cell. During development, an embryo goes through the blastocyst stage just before it implants in the uterus. Embryonic stem cells are useful for experiments because they are self-renewing and able to develop into almost any cell type in the body. Martin later identified a key chemical component in limb development and continues to study embryogenesis, or the growth of embryos over time. Martin’s work on embryonic stem cells has allowed scientists to further research and treat human diseases, and her study of how organs form has helped scientists learn about the healthy growth of embryos.