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Fertility Glossary

Zygote

The single cell formed immediately after normal fertilisation, before it starts dividing.

Embryology

A zygote is the single cell that results when an egg and sperm fertilise normally, seen briefly with two pronuclei before the first cell division takes place, usually within a day of fertilisation. The zygote stage is short; embryology reports quickly move on to describing the number of cells present as the embryo begins to divide.

Also known as: fertilised egg

Sources

  • ICMR Standard Treatment Workflows (icmr.gov.in/standard-treatment-workflows-stws)

Last reviewed: 9 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.

Related terms

Pronuclei (PN) and normal or abnormal fertilisation

Two visible structures seen the morning after IVF that confirm normal fertilisation; other counts need a closer look.

Fertilisation

The fusion of egg and sperm to form an early embryo.

Cleavage-stage embryo

An early embryo, usually seen on Day 2 or Day 3, made up of a small number of dividing cells.

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