ABSTRACT
In 1981, ESCs were isolated from early mouse embryos, which later led to the development of a method to derive stem cells from human embryos, which can grow in the laboratory. Stem cells that are isolated from the human embryo are called human ESCs. Furthermore, human embryos used in these studies are created for reproduction by using in vitro fertilization procedures. When these embryos are no longer needed by the patients, they can be donated for research with the informed consent of the donor. Moreover, stem
cells are important to living organisms for many reasons. The 3-to 5-day-old embryo that is called a blastocyst contains cells normally referred to as the inner cells. The inner cell mass contains stem cells that give rise to the entire body of the organism, including many specialized cell types and organs such as the skin, sperm, eggs, heart, lung, and other tissues. Stem cells are unique in many aspects as explained in Figure 7.3 as well as in Table 7.1.
