Xue Feng

By Bin Wu, Xue Feng, Suzhen Lu and Timothy J. Gelety

Human IVF laboratory often shows many abnormal fertilization eggs, such as no pronucleus (0PN), monopronucleus (1PN), three pronuclei (3PN) or multi-pronuclei (mPN) zygotes and these abnormal eggs are usually not used and typically discarded. Recent researches have showed that further evaluation on these abnormal eggs may provide some hope for aged infertile couples to have babies in their family. Our study showed that 0PN eggs may be rescued by introcytoplasmic sperm injection (ICSI). The 1PN zygotes should be cultured to observe their cleavage and blastocyst formation until Day 3 to Day 6. Selecting normal chromosomal embryo transfer may have healthy baby birth. Although most of 3PN embryos are genetically abnormal chromosomal composition, a small portion of 3PN embryos may develop to blastocyst with normal chromosomal composition. Also, those embryos derived from 3PN, especially by ICSI, have more possibility for self-correction to become normal euploid embryos. The microsurgically removing 1PN from 3PN zygotes may artificially correct this abnormal fertilization. After one PN removal, the formed blastocyst may be screened by the PGT for embryo transfer in rare embryo patients to achieve pregnancy and delivery of a healthy newborn. Based on no obvious difference of ooplasm between normal fertilized 2PN and 3PN zygotes, the cytoplasm of 3PN zygotes may be used to supplement the aged woman poor oocytes to improve embryo quality. Transferring partial cytoplasm from 3PN zygote to the fertilized 2PN zygotes of aged woman may promote the receipt embryo to develop blastocysts. This partial ooplasmic transfer does not change the aging woman genetic composition and the woman embryos still keep her with her husband genetic genes in the cell nucleus. However, the baby born with this technique might appear epigenetics because the mixed mitochondrial DNA would be passed on to all future generations.

Part of the book: New Perspectives in Human Embryology