1,2 1Department of Molecular Biology, MGH Research Institute, Massachusetts General Hospital, Boston, Massachusetts 02114, USA; 2Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; 3Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology, and Research (A*STAR), Proteos, Singapore 138673, Republic of Singapore; 4Reproductive Biology Group, Division of Developmental Biology, Department of Biology, Faculty of Science, Utrecht University,...