Self-correction in tripronucleated human embryos

Abstract

Objective: To explore the occurrence of ploidy and parental self-correction in tripronuclear (TPN) human embryos.

Design: Experimental.

Setting: Research facility.

Patient(s): Thirty-two TPN embryos resulting from intracytoplasmic sperm injection (ICSI-TPN) and 18 TPN embryos resulting from conventional IVF (IVF-TPN).

Intervention(s): Tripronuclear embryos were cultured in vitro for 6 days. Those with ≥ 6 cells were biopsied for ploidy analysis. Blastocysts were studied for ploidy or parental inheritance. Heteroparental inheritance was determined after comparing polymorphic loci in the genomic DNA of a blastocyst and in the parents' DNA.

Main outcome measure(s): Tripronuclear origin, cell number at biopsy, chromosome analysis using fluorescent in situ hybridization, parental inheritance analysis using polymerase chain reaction amplification and sequencing, in vitro development to the blastocyst stage, and percentage of diploid and triploid cleavage embryos and blastocysts.

Result(s): Half of ICSI-TPN embryos became self-corrected blastocysts whereas only one IVF-TPN embryo did.

Conclusion(s): Both ICSI-TPN and IVF-TPN embryos are capable of self-correction, but the latter to a lesser extent. Neither parental inheritance nor ploidy determines the ability of a TPN embryo to progress to the blastocyst stage. However, the ability of a TPN embryo to become self-corrected is determined by the parental origin of the extra pronucleus.