Fig. 4. Fluorescent images of 2-cell embryos stained with antibodies that recognized acetylated histones. Histone H3 acetylated on lysine 9 (H3K9) and H4K8, but not H3K14, are known to be sensitive to histone deacetylases. HSC clone embryos were more intensely stained for H3K9 and H3K14 than cumulus clone embryos or intracytoplasmic sperm injection (ICSI) embryos. Dot-like areas were frequently noted in HSC clone embryos (arrowheads). In HSC clone embryos, the two blastomeres were often stained differentially for H4K8. There was no difference in the staining pattern for H3K14 among the three types of embryos. 6-12 embryos were observed in each group.