FIG. 1.

hESC colonies contain two different cell types based on Oct4 or GATA6 expression. (A) Phase-contrast image of hESCs forming SD-ESCs (black arrow). The right image was magnified in the red box of the left image. (B) Phase-contrast (a) and fluorescent immune-staining (b–d) analysis was conducted after cell culture for 5 days. OCT4 (green) (b) and GATA6 (red) (c) were detected in the two distinctive colonies consisting of pluripotent and primitive endoderm cells, respectively. Nuclei were stained with DAPI (blue) (d). Scale bar represents 50 μm. (C) Expression of marker genes for pluripotency (OCT3/4, SOX2, and NANOG), primitive endoderm (GATA6 and GATA4), and three germ cell layers (NEUROD1, HAND1, BMP4, and AFP) was examined by RT-PCR (a) and western blot (b) in undifferentiated and SD-hESCs. SD-hESC, spontaneously differentiated human embryonic stem cell; RT-PCR, real-time–polymerase chain reaction. Color images available online at www.liebertpub.com/scd