Glossary · Definition · v2026.3
What Is a Blastomere?
A blastomere is an individual cell within an early-stage embryo produced by cleavage division after fertilization. Each blastomere contains a complete copy of the embryo's genome.
Clinical significance
Embryologists assess blastomere number, symmetry, and fragmentation during Day 2 and Day 3 embryo grading. Uneven blastomere size or excessive fragmentation may indicate reduced developmental potential.
Common confusion
Blastomeres are not stem cells. They are undifferentiated cells of the early cleavage-stage embryo that have not yet committed to a specific lineage.
Related reference
Used in
This content defines terminology for educational orientation. It does not constitute medical advice.
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