Alireza Fazeli, PhD, is a Professor of Reproductive and Developmental Medicine at the University of Sheffield, Department of Human Metabolism. His research interests focus on the cross-talk between gametes and embryos, and the maternal tract. Dr. Fazeli is a Trustee of the Infertility Research Trust, and a member of the Editorial Board for the journal Reproduction.William V. Holt, PhD, is a Visiting Professor in the Academic Unit of Reproductive and Developmental Medicine at the University of Sheffield, and former head of Reproductive Biology unit at the Institute of Zoology, Zoological Society of London. His research focuses on understanding the mechanisms governing sperm survival during the freeze-thaw process in small population breeding programs, as well as broader research on the cellular mechanisms involved in the processes leading to fertilization. Dr. Holt is the co-Chair of the Health and Safety subcommittee of the Companion and Domestic Animals and Endangered Species group of the International Embryo Transfer Society.