Synonyms: Fertilized egg

Medical Specialties: Family practice, Internal medicine, Obstetrics/gynecology

Clinical Definition

A zygote is the union of a sperm and egg cell. It contains all the genetic information needed to form a human being, with half of the information originating from the egg and half from the sperm. The zygote travels down the fallopian tube and divides to become a blastocyst and eventually an embryo. 

In Our Own Words

A zygote is a fertilized egg. It forms when a single sperm enters the mother's egg cell. It contains all the DNA or genetic information necessary to form a baby. Half the information is from the mother and the other half from the father.


If in-vitro fertilization (IVF) techniques are used, the sperm and egg may be mixed in a culture dish and then inserted into the fallopian tubes or uterus.

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