Iowa

STEM CELLS GIVE rise to many different cell types that make up an organism. They can be classified according to their origin as embryonic stem cells, fetal stem cells, or adult stem cells. Embryonic stem cells are harvested through in vitro extraction of the inner cell mass of a blastocyst, the earliest stage following fertilization, when the embryo consists of only a few cells.

Fetal stem cells are collected from various regions of the fetus later in development. As such, fetal cells are partially differentiated at the time of harvest and are therefore more limited in their ability to give rise to tissues in the body compared to embryonic stem cells. Adult stem cells are harvested from an individual any time after birth and maintain their ...