Fig. 4. Mll2 is cell autonomously required. Chimeras made with wild type +/+ (A,E,I), Mll2^+/– (B,F,J) or Mll2^–/– (C,D,G,H,K,L) ES cells were harvested at the times indicated and stained for ß-galactosidase expression after sectioning (E18.5) or not (E8.5, E9.5). Embryos with Mll2^–/– cells were divided into low (<50%) or high (>50%) percentage according to the intensity of staining. Blue stained cells were broadly distributed in all Mll2^+/– and low percentage Mll2^–/– embryos, except for E18.5^–/– (K), where only a few blue staining cells could be observed in the condensing oral cartilage (L, a magnification of the boxed region in K), as well as the endogenous ß-galactosidase activity in the gut (I,J,K).