1. Reproductive Molecular Research Group, Department of Pathology, University of Cambridge (J.M.H., D.R.L., D.S.C.-J., S.K.S.), Cambridge, United Kingdom CB2 1QP
2. Department of Anatomy, University of Cambridge (G.J.B.), Cambridge, United Kingdom CB2 3DY
3. Department of Obstetrics and Gynecology, Rosie Hospital (D.S.C.-J., S.K.S.), Cambridge, United Kingdom CB2 2QH