Novel flow‐cytometric method for separating cell types in differentiated F9 embryoid bodies

The differentiation of F9 teratocarcinoma cells mimics the formation of a mouse embryonic tissue, the primitive endoderm. In vitro, small aggregates of F9 cells, termed embryoid bodies, differentiate in response to retinoic acid and develop a surface epithelium that is characterized by the production of α‐fetoprotein. In the present study, cellular autofluorescence profiles obtained by fluorescence‐activated cell sorting demonstrated that undifferentiated embryoid bodies were composed of a single type of cell. In contrast, retinoic acid‐induced embryoid bodies were composed of two cell types: a major population displaying autofluorescence levels similar to those of cells from undifferentiated embryoid bodies and a second population displaying higher autofluorescence. RNA analyses demonstrated that the transcription of α‐fetoprotein was associated only with the more highly autofluorescent population, indicating that flow cytometry provides a novel mechanism for the separation of undifferentiated cells from differentiated endoderm cells in F9 embryoid bodies. © 1995 Wiley‐Liss, Inc.