sperm and ova
Getting cells to revert to a stem-like state – creating so-called induced pluripotent stem (iPS) cells – was a true revolution, but the technique invented in 2006 is only half the game. The first challenges include getting enough adult cells to undergo the “reprogramming” in culture to be of use and removing those traces of “priming” that distinguish them from true embryonic stem cells. The second is keeping them in the iPS state – that is, holding back their urge to differentiate – in lab conditions. And then there is the challenge of directing their differentiation in the way that you want…