1. Division of Reproductive Biology (S.M., C.K., J.R., A.J.W.H.), Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California 94305-5317
2. Developmental and Reproductive Biology Program (N.K.-O., D.G.M., O.R.), Biomedicum Helsinki and Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, 00014 Helsinki, Finland
3. Department of Cellular Biochemistry (O.K.), Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands