The percentage of ES cells differentiates into TH-positive cells in vitro culture. (A) GFAP (red) and tyrosine hydroxylase (green) immunostaining after exposure FGF8b and Shh. At this stage almost no GFAP-positive glia cells were detected in the differentiating ES cells on day 10. (B) TH and DAT staining are two markers of dopamiergic neurons. (C) The efficiencies of the dopaminergic neuron induction: 18.7 ± 4.3% (Shh/FGF8b-treated ES cells) v.s. 2.4 ± 1.1% (mock-treated ES cells). The TH-positive cells were manually counted in total cells. The scale bar is 15 μm.