Preface

Birth and clinical pregnancy from fresh and frozen oocytes fertilized with cryopreserved testicular spermatozoa

This is the first report showing a second clinical pregnancy of a couple who already have a baby from a previous frozen embryo transfer cycle when the embryos were generated from fresh oocytes that were fertilized by intracytoplasmic sperm injection (ICSI) using frozen testicular spermatozoa (the couple have unsuccessful fresh and frozen embryo transfer cycles). Fifty-two months after the first IVF/ICSI cycle the couple had their second IVF/ICSI cycle, but the collected oocytes (n=8) were frozen because no spermatozoa was obtained from the frozen testicular tissue samples which were cryopreserved prior to the first IVF/ICSI cycle. New testicular tissue samples were obtained and frozen. Finally, 58 months after the first IVF/ICSI cycle all of the 8 frozen oocytes of the couple were thawed and fertilized by ICSI using frozen testicular spermatozoa obtained from the newly cryopreserved testicular tissue. Three embryos were transferred and the couple has an ongoing pregnancy, which is in the 20(th) week of pregnancy. Our case report shows that: 1) developmentally competent embryos can be generated by ICSI of frozen-thawed testicular spermatozoa into both fresh and frozen human oocytes, and 2) clinical pregnancy and a healthy baby can be conceived from both frozen and fresh oocytes fertilized with cryopreserved testicular spermatozoa.