Metaphase II nuclei generated by germinal vesicle transfer in mouse oocytes support embryonic development to term.
BACKGROUND
Cytoplasmic defects are thought to cause aneuploidies in oocytes and embryos and oocyte 'reconstruction' by germinal vesicle (GV) transfer may circumvent such defects. In mice 'reconstructed' oocytes undergo meiosis and fertilize normally, but early embryonic development is compromised if their ooplasm matured in vitro. This study employs sequential MII spindle and/or pronucleus (PN) transfer to assess the embryonic potential of MII nuclei that form following GV transfer.


RESULTS
Mouse embryos generated by these procedures were transferred to the oviducts of pseudopregnant mice to monitor pregnancy outcome. Following GV transfer, the resultant metaphase II (MII) nuclei were activated either in situ or transferred and activated in ooplasts from in-vivo matured oocytes. When exchanged with the female PN of a fertilized zygote, only the PNs that developed in in-vivo matured ooplasts generated live offspring. Viable offspring also resulted when MII nuclei were transferred to in-vivo matured ooplasts and fertilized by insemination with sperm or by artificial activation and male PN transfer. Significantly, the offspring displayed normal fertility as adults.


CONCLUSIONS
This report of live births following GV transfer in mice illustrates the importance of the maturational history of the ooplasm at PN formation for normal embryonic and fetal development.
Liu
Hui
H
Program for In vitro Fertilization, Reproductive Surgery and Infertility, New York University School of Medicine, New York, NY 10016, USA.
Chang
Hung Chi
HC
Zhang
John
J
Grifo
Jamie
J
Krey
Lewis C
LC
D000818:Animals; D001723:Birth Rate; D002467:Cell Nucleus / Q000502:physiology*; D005314:Embryonic and Fetal Development; D005260:Female; D005298:Fertility; D008297:Male; D008677:Metaphase; D051379:Mice; D008815:Mice, Inbred Strains; D008846:Micromanipulation; D053652:Nuclear Transfer Techniques; D009865:Oocytes / Q000502:physiology*; D011247:Pregnancy; D008941:Spindle Apparatus / Q000637:transplantation