The potential for derivation of embryonic stem cells in vertebrates.

An analysis of embryonic stem cell (ESC) derivation in vertebrates has revealed that the potential to form ESC is dependent on the setting aside of a pluripotent lineage from extraembryonic lineages early in development. Derivation of ESCs from all amniotes and also many lower vertebrates with that pattern of lineage allocation is thus predictable. Culture conditions during derivation in all groups share some similar characteristics, most of which are related to retaining potency coupled with extensive proliferative capacity. This in turn probably reflects the environment that maintains and causes the primordial germ cells (PGC) to proliferate in vivo. Hence culture usually involves feeder layers and serum or factors derived from them and the use of small clumps of pluriblast or epiblast cells instead of total dissociation, to facilitate cell-cell signalling. Currently addition of FGF has proven to be important but that of LIF has not been fully explored. Copyright 2005 Wiley-Liss, Inc