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Distinct Morphokinetic Signature of Human Embryos with Chromosomal Mosaicism
Margarita Ruseva1, Sophia Zlatanova2, Stefka Nikolova2
1Research Department, Nadezhda Women's Health Hospital, 1373 Sofia, Bulgaria.
Genes
|November 27, 2025
Summary
Chromosomal mosaicism in embryos shows delayed early development but normal later milestones, unlike aneuploid embryos which exhibit significant delays throughout development. This finding aids in understanding embryo development and PGT-A results.
Area of Science:
- Embryology and Reproductive Genetics
- Genetics and Genomics
- Assisted Reproductive Technologies
Background:
- Chromosomal mosaicism in human blastocysts, identified via preimplantation genetic testing for aneuploidy (PGT-A), presents a diagnostic challenge.
- Understanding the developmental trajectory of mosaic embryos is crucial for improving IVF outcomes and genetic counseling.
Purpose of the Study:
- To investigate if chromosomal mosaicism in blastocysts is associated with a unique morphokinetic signature.
- To differentiate the developmental patterns of euploid, mosaic, and aneuploid embryos using time-lapse imaging.
Main Methods:
- 182 human embryos underwent trophectoderm biopsy and next-generation sequencing for PGT-A, classifying them as euploid (n=55), mosaic (n=39), or aneuploid (n=88).
- Embryos were cultured in a time-lapse system (EmbryoScope), with 12 morphokinetic parameters analyzed, including pronuclei fading (tPNf), cleavage times (t2-t9), morula formation (tM), blastulation start (tSB), and full blastocyst formation (tB).
- Morphokinetic parameters were statistically compared between ploidy groups.
Main Results:
- Mosaic embryos, particularly low-grade mosaicism, demonstrated delayed pronuclei fading (tPNf) and initial cleavage (t2) compared to euploid embryos.
- Whole-chromosome mosaicism was linked to delayed embryo development at intermediate cleavage stages (t3, t4, t6, t7, t9).
- Aneuploid embryos, especially those with concurrent mosaicism, showed significant developmental delays at later stages (t7, t8, tM, tB) compared to euploid embryos.
Conclusions:
- Mosaic embryos display early developmental delays but achieve later morphokinetic milestones at rates comparable to euploid embryos.
- Aneuploid embryos, particularly those with mosaicism, exhibit pronounced developmental delays in later stages, suggesting a more severe impact on development.
- Morphokinetic analysis can potentially aid in distinguishing developmental patterns associated with different chromosomal statuses in embryos.
Keywords:
morphokinetic parametersmosaic embryosnext generation sequencing (NGS)preimplantation genetic testing for aneuploidy (PGT-A)time-lapse monitoring (TLM)More Related Videos
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