Oocyte euploidy, pronuclear zygote morphology and embryo chromosomal complement

Area of Science:

• Reproductive biology
• Embryology
• Genetics

Background:

• Pronuclear morphology is a potential indicator of embryo development and chromosomal status.
• This study evaluated pronuclear morphology in zygotes from euploid oocytes and compared it to chromosomally normal embryos.

Purpose of the Study:

• To assess the correlation between pronuclear morphology and euploidy.
• To compare pronuclear morphology with chromosomal normality determined by blastomere analysis.
• To evaluate the predictive value of pronuclear morphology for implantation rates.

Main Methods:

• Group 1: Assisted conception cycles with aneuploidy screening on first polar body (PB1) of oocytes.
• Group 2: Assisted conception cycles with aneuploidy screening on day 3 embryos.
• Pronuclear morphology was assessed 16 hours post-insemination in both groups.

Main Results:

• Seventy-three percent of zygotes in Group 1 exhibited specific configurations (centralized/juxtaposed pronuclei, specific nucleoli/PB positions).
• These configurations in Group 2 correlated with the highest proportion of chromosomally normal embryos.
• These morphology patterns showed higher implantation rates in both groups compared to others.

Conclusions:

• Certain pronuclear morphology patterns are linked to increased euploidy and implantation success.
• Pronuclear morphology scoring is relevant for predicting zygote viability.
• This method aids in selecting viable embryos during assisted reproductive technologies.