1. MRC Human Reproductive Sciences Unit, Centre for Reproductive Biology, The Queen’s Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, Scotland, United Kingdom, Research Group for Receptor Biology, Institute for Infectious Diseases and Molecular Medicine, The University of Cape Town, Anzio Road, Observatory 7925, South Africa, and School of Physiology, University of the Witwatersrand Medical School, 7 York Road, Parktown, 2193, South Africa