ABSTRACT
A stem cell can replicate itself and produce cells that take on more specialized functions. The breadth of function adopted by the more differentiated daughter cells and their progeny is commonly referred to as the developmental potential or potency of the stem cell. The inner cell mass gives rise to two groups of cells. The hypoblast, which contributes to extraembryonic endoderm, and the epiblast, which further differentiates during gastrulation to form the three germ layers of the embryo: ectoderm, mesoderm, and endoderm. Embryonic germ (EG) cells are a lesser-known type of embryonic pluripotent stem cell, as compared with embryonal carcinoma (EC) and embryonic stem cells. EG cells are derived from primordial germ cells. The status of human EC cells as chromosomally abnormal and neoplastic make their differentiated post-mitotic cell products an unlikely candidate for human cell therapy. However, the strong desire to treat certain diseases has led to their use in clinical trials.
