Scientists at the University of Cambridge working with the Weizmann Institute have created primordial germ cells – cells that will go on to become egg and sperm – using human embryonic stem cells. Although this had already been done using rodent stem cells, the study, published today in the journal Cell, is the first time this has been achieved efficiently using human stem cells.
When an egg cell is fertilised by a sperm, it begins to divide into a cluster of cells known as a blastocyst, the early stage of the embryo. Within this ball of cells, some cells form the inner cell mass – which will develop into the foetus – and some form the outer wall, which becomes the placenta. Cells in the inner cell mass are ‘reset’ to become stem cells – cells that have the potential to develop into any type of cell within the body. A small number of these cells become primordial germ cells (PGCs) – these have the potential to become germ cells (sperm and egg), which in later life will pass on the offspring’s genetic information to its own offspring.