Metaphase II (MII) human oocytes with smooth endoplasmic reticulum clusters do not affect blastocyst euploid rate

Area of Science:

• Reproductive biology
• Human embryology
• In vitro fertilization

Background:

• Oocyte morphology is a key factor in assessing reproductive potential.
• Dysmorphisms in mature human oocytes, such as smooth endoplasmic reticulum clusters (SERc), are observed but their impact on euploidy and pregnancy outcomes is not fully understood.

Purpose of the Study:

• To determine if specific oocyte dysmorphisms, particularly SERc, affect the euploidy rate of resulting blastocysts.
• To evaluate the relationship between oocyte morphology and pregnancy outcomes following preimplantation genetic testing for aneuploidies (PGT-A).

Main Methods:

• Retrospective analysis of 590 biopsied blastocysts from 109 patients undergoing PGT-A cycles.
• Morphological assessment of metaphase II (MII) oocytes.
• Chromosome status determined by array comparative genomic hybridization (aCGH) or next-generation sequencing (NGS).

Main Results:

• No statistically significant relationship was found between oocyte dysmorphisms and the euploid rate of blastocysts.
• Oocytes with SERc showed a trend towards higher 2-pronuclei arrest but did not affect blastocyst formation rates.
• Two healthy singleton births resulted from embryo transfers derived from oocytes with SERc.

Conclusions:

• Oocyte dysmorphisms, including SERc, do not appear to compromise blastocyst euploidy rates or embryo formation.
• Embryos originating from oocytes with SERc are potentially viable and can be considered for transfer, especially when alternative options are limited.