Cell Progeny | © Edmond Alexander
Stem cells are found in most multi-cellular organisms. They are capable of retaining the ability to reinvigorate themselves through mitotic cell division and can differentiate into a diverse range of specialized cell types. There are three main types of mammalian stem cells: embryonic stem cells, derived from blastocysts; adult stem cells, which are found in some adult tissues; and cord blood stem cells, which are found in the umbilical cord. For Heart Healthy Living magazine, Better Homes & Gardens, Inc.