Mouse embryonic stem (ES) cells demonstrate two unique properties (pluripotency and self-renewal) that facilitate in vitro studies of cellular differentiation into cell types of all three embryonic germ layers. Much of the recent interest in ES cell research comes from the possibility of developing cell replacement therapies for a wide range of human disorders including neurodegenerative diseases and endocrinopathies. A variety of different cell types have been generated from ES cells, most commonly via the generation of cellular aggregates called embryonic bodies (EB). Their conversion into...