Fertility Glossary

Mature egg (MII oocyte)

An egg ready to be fertilised.

Only mature eggs, described as metaphase II or MII, can be fertilised. Not every egg collected will be mature, which is why the number of eggs collected and the number fertilised differ.

Related terms

Egg collection

Removing eggs from the ovaries with a needle guided by ultrasound.

Fertilisation

The joining of egg and sperm to form an embryo.

ICSI

A single sperm is injected directly into an egg during IVF.

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