Figure 1: Maintenance of the H1 hESC line. (a) Colony of H1 hESC showing the morphology typical of pluripotent stem cells, including prominent boarders (×20 magnification). (b) Expression by H1 hESC of the transcription factor Oct-4 and the surface marker SSEA-4, both of which correlate with pluripotency. Dead cells were removed from flow cytometric analysis using 7-AAD staining. Open histograms represent appropriate isotype controls.