The biological characteristics and differentiation of embryonic stem cells in vitro

Embryonic stem cells (ES cells), present in the early stages of embryo development, are capable of unlimited, undifferentiated proliferation in vitro. Along with the innovation of the methods for ES cell culture in vitro, many ES cell lines derivated from cultured primordial germ cells or inner cell mass of blastocysts of animals and human have been established recently. ES cells, with their potential to differentiate into a wide variety of cell types in chemically defined medium, would be invaluable for studies of some aspects of embryogenesis and cells differentiation. It will provide a powerful tool for biological research, transgenic animal making, transplantation therapies, and drug development.