Abstract:Embryonic stem (ES) cells derived from blastocyst stage eary mammlian embryos are unique cell populations with the ability to undergo both self renewal and differentiation into all types of somatic cells. A wide variety of adult tissues harbors stem cells, yet called "adult" stem cells may be capable of developing into a limited number of cell types. Based on this property and combination with clone technique,the stem cell technology could be applied mainly in the following fields: (1) ES cells will provide a useful culture system for cell differentiation to study the mechnism underlying many facets of mammalian development; (2) ES cells represent one of the most important materials in genetic manipulation including the targeted mutation of specific genes; (3) Human ES cell based transplantation therapy will hold great promise to treat successfully a veriety of diseases though many barries remain in the way of successful clinical trials; (4) Human ES cells and adult stem cells could potentially provide an unlimited supply of tissue for transplantaion, as a seed cell sourse.