Fig. 3. Downregulation of Nanog expression in ES cells upon aggregation. Whole-mount X-Gal staining of Nanog ßgeo ES cells that were aggregated for the indicated number of days in the presence of LIF (LIF+) or the absence of LIF (LIF–). Rosa26 ES cells were stained as a positive control for whole-mount X-gal staining (Rosa). The paraffin sections were counterstained with eosin Y (pink). Bars, 50 µm.