This protocol describes the culture of embryonic stem (ES) cells using mitotically inactivating primary mouse embryonic fibroblast (MEF) cells as a feeder layer (preparation described in Preparation of Mouse Embryonic Fibroblast (MEF) Feeder Plates). The ES culture medium is supplemented with recombinant leukemia inhibitory factor (LIF) to help maintain the cells as pluripotent stem cells. This protocol has been optimized for the ES-D3 cell line.
