Induction of cellular differentiation by retinoic acid in vitro

Cellular differentiation by the vitamin A derivative retinoic acid (RA) has been studied with undifferentiated pluripotent embryonic carcinoma (EC) an d embryonic stem (ES) cells in vitro. Both cellular systems are suitable to study differentiation of various cell types, because they recapitulate ear ly stages of mouse embryogenesis, In vivo, RA was identified as a morphogen ic and teratogenic compound and furthermore as a signalling molecule influe ncing gene expression in a complex manner via a family of RA receptors, Her e, we summarize in vitro studies with ES and EC cells in comparison to in v ivo studies that have contributed to our understanding how lRA influences d ifferentiation and regulates gene expression. We demonstrate that modulatio n of ES cell differentiation in vitro by RA depends on the concentration an d developmental stage of application which is comparable to its stage-depen dent influence on embryonic development in vivo. Copyright (C) 1999 S. Karg er AG, Basel.