1. 1MRC Human Reproductive Sciences Unit, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, Scotland, U.K., and School of Clinical Sciences and Community Health, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, Scotland, U.K.
2. 2MRC Human Reproductive Sciences Unit, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, Scotland, U.K., and School of Clinical Sciences and Community Health, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, Scotland, U.K.