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Parthenogenetic activation and development of fresh and aged human oocytes
N Winston1, M Johnson, S Pickering
1Department of Anatomy, University of Cambridge, London, United Kingdom.
Objective:
To develop a systematic study of the parthenogenetic activation and early development of human oocytes.
Design:
Human oocytes (both freshly retrieved and remaining unfertilized after exposure to spermatozoa) were exposed to alcohol or calcium ionophore and examined for evidence of activation.
Setting:
Academic research department of a teaching hospital.
Patients, Participants:
Couples donating oocytes were undergoing therapy for infertility with in vitro fertilization or gamete intrafallopian transfer.
Interventions:
Gonadotropin-releasing hormone agonist and human menopausal gonadotropin were administered at therapeutic doses.
Main Outcome Measures:
After application of activation stimuli at varying doses and durations, oocytes were examined for evidence of meiotic reactivation, pronuclear formation, deoxyribonucleic acid content, and cleavage.
Results:
Fresh and aged human oocytes can be activated parthenogenetically using a calcium ionophore but at lower rates than seen for mouse oocytes (typically 50% to 60% versus 90% to 100%, respectively). Ethanol was a poor activating agent (maximum activation rate 16%). Human parthenotes can complete division to the eight cell stage.
Conclusions:
These results indicate that parthenote embryos may provide a source of material to study changes that occur during early human development. The data also raise the possibility that some early human pregnancy losses may involve oocytes that have been parthenogenetically activated spontaneously.