Examination of colonies derived from the colony-forming assays using fetal liver cells at E12.5. (A, C, E, G, and I) The appearance of the colonies at the 7th and (B, D, F, H, and J) at 14th days of culture. Arrows indicate small colonies that had appeared at 14th day of culture in Mll^mu/mu. (E through J) Magnified views of single colony. (A, B, E, and F) Mll^+/+; (C, D, G, H, I, andJ) Mll^mu/mu.