Fig. 8. Distribution of Me(3)K20H4 in oocytes and one- and two-cell mouse embryos. (A,D,G,J,M,P) Oocytes and one- and two-cell embryos stained with DAPI. The sperm (sp), maternal (ma), paternal (pa) and polar body (pb) DNA stains intensely with DAPI compared with the cytoplasm. (B,E,H,K,N,Q) The same embryos were stained using the anti-Me(3)K20H4 antibody and the immunofluorescence (FITC) is shown in green. (C,F,I,L,O,R) Merged images of the embryos in the left and the middle columns. DAPI is pseudocoloured in red; colocalisation is yellow. (A-C) Me(3)K20H4 is enriched in the maternal centromeres of a metaphase II-arrested oocyte. (D-F) Approximately 1 hour after fertilisation (n=10) the sperm nucleus is found in the ooplasm and lacks Me(3)K20H4, while the polar body and the maternal chromosomes contain Me(3)K20H4. (G-I) Me(3)K20H4 is present in the maternal pronucleus but undetectable in the paternal pronucleus (pronuclear stage: n=32). (J-L) At syngamy (n=33) the difference in Me(3)K20H4 between the parental chromosomes is clear. (M-O) Me(3)K20H4 staining is partitioned in the late telophase/early G1 phase two-cell embryo (early two cell; n=15). (P-R) At late two-cell embryos (n=35) the intensity of Me(3)k20H4 staining is very weak. Scale bars: 10 µm (A-L); 10 µm (M-R).