Pregnancy and live birth following the transfer of vitrified-warmed blastocysts derived from zona- and corona-cell-free oocytes.
This study reports two clinical pregnancies and one live birth following the transfer of vitrified blastocysts developed from oocytes with neither zona pellucida nor corona cells. Two zona-free oocytes obtained from two patients of advanced maternal age undergoing minimal stimulation were normally fertilized after intracytoplasmic sperm injection. In case 1, all four blastomeres of the zona-free embryo were loosely associated and inserted back into ruptured zona on day 2. Zona-free embryo from case 2 had tight contacts between blastomeres and was cultured without zona. Both embryos derived from zona-free oocytes progressed to blastocyst stage and were cryopreserved by vitrification. When patients came back for a cryopreserved embryo transfer, both vitrified blastocysts survived warming. In case 1, transfer of a warmed blastocyst with reconstructed zona resulted in a clinical pregnancy that ended in a spontaneous abortion at 22 weeks. In case 2, live birth was achieved with a normal healthy baby (male) weighing 2381 g at 40 weeks' gestation. This report emphasizes the importance of maintenance of normal cell arrangement on the subsequent embryonic development for a zona-free oocyte. Zona-free oocytes may provide a valuable source of embryos for infertility patients, especially for those with a limited number of oocytes.
Shu
Yimin
Y
New Hope Fertility Center, 784 Park Avenue, New York City, NY 10021, USA; IVF Program, Stanford University Medical Center, Palo Alto, CA 94304, USA. shuyimin@hotmail.com
Peng
Wenlin
W
Zhang
John
J
D000328:Adult; D001755:Blastocyst / Q000502:physiology*; D015925:Cryopreservation / Q000379:methods; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D006801:Humans; D050498:Live Birth; D008297:Male; D008423:Maternal Age; D009865:Oocytes / Q000254:growth & development; D011247:Pregnancy; D012662:Semen Preservation; D020554:Sperm Injections, Intracytoplasmic; D058989:Vitrification; D015044:Zona Pellucida / Q000502:physiology*