Fig. 5. Widespread apoptosis in E9.5 Mll2^–/– embryos. Paraffin sections were taken from an Mll2^–/– embryo (A) and a Mll2^+/+ littermate (B), stained with TUNEL and then with Hematoxylin and Eosin. For greater contrast, A shows a section after TUNEL but before Hematoxylin and Eosin staining. (C) The average ratio of apoptotic cells to total cells from three embryos each yields the apoptotic index.