A) Sep+/+ or Sep-/- oocytes were matured in vitro until metaphase II. Sep-/- oocytes were injected with wild-type separase or cleavage mutant separase encoding mRNAs in metaphase II. Oocytes were either fixed in metaphase II or activated and fixed in anaphase II. Spreads were stained with Rec8 antibody (red), CREST serum (green), and DAPI (blue) to label DNA. n indicates the number of oocytes with the shown phenotype (e.g. in anaphase II, after successful activation) and the total number of oocytes analysed 