[Derivation of germ cells from mouse embryonic stem cells in culture]

Mouse embryonic stem cells derive from the inner cell mass of the blastocyst and give rise to the three primitive embryonic layers, which later will form all the different tissue types of an adult. Embryonic stem cells are thus defined as totipotent cells. In vitro, these cells can give rise to all the somatic cells. Different laboratories have now shown that cultured embryonic stem cells can also differentiate into germline cells. By using the transcription factor Oct-4 as a tool for the visualization of germ cells, it has been shown the derivation of oocytes from mouse embryonic stem cells. These works should contribute to various areas, including therapeutic cloning which associates nuclear transfer and selective production of a specific cell type.