What Are Pronuclei (2PN)?

Pronuclei (2PN) describes the appearance of two visible nuclei within a fertilized egg, one from the egg and one from the sperm, typically observed about 16 to 20 hours after fertilization.

Clinical significance

The presence of two pronuclei is considered a sign of normal fertilization and is used by embryologists to identify embryos suitable for further development in IVF laboratories.

Common confusion

A fertilized egg with two pronuclei does not always develop into a viable embryo; some embryos arrest in later stages of development.

Related reference

/glossary/fertilization-rate →/glossary/embryo-culture →/glossary/embryo-arrest →/glossary/blastocyst →← Back to Glossary Index

Used in

Fertilization Rate →Embryo Culture →Embryo Arrest →Blastocyst →

This content defines terminology for educational orientation. It does not constitute medical advice.

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