Figure 1: The pluripotent state of hESCs maintained under the defined culture is associated with an acetylated chromatin. (A) High level of expression and nuclear localization of acetylated histone H3 (acH3, green) in undifferentiated hESCs, as indicated by Oct-4 (red) expression, inside the colony, and significantly reduced immune-reactivity of differentiated cells outside the colony. (B) High level of expression and nuclear localization of acetylated histone H4 (acH4, green) in undifferentiated hESCs, as indicated by Oct-4 expression, inside the colony, and significantly reduced immunereactivity of differentiated cells outside the colony. (C) Moderate histone H3 K4 methylation (meH3K4, red) and H3 K27 methylation (meH3K27, green), and undetectable histone H3 K9 methylation (meH3K9, red) in hESCs maintained under the defined culture. All cells are shown by DAPI staining (blue). High-resolution microscopic images in the bottom panel reveal cellular localization patterns.