Schematic representation of the derivation of monkey embryonic stem cells. ART-produced embryos are cultured to the expanded blastocyst stage before the trophectoderm is selectively lysed by immunosurgery. The ICM is recovered and cultured on mitotically-inactivated, mouse fetal fibroblasts. Epithelial outgrowths are harvested and dissociated before replating on the coculture. Eventually, ES cell colonies emerge that are selected, expanded and eventually subcloned before characterization .