Immature egg

Immature eggs, described as germinal vesicle or MI stage, have not completed the maturation needed for fertilisation. Some laboratories attempt to mature them briefly in culture, but success is limited and any embryos formed are generally less likely to develop. Having some immature eggs in a collection is normal.

Also known as: MI oocyte, germinal vesicle, GV egg

Last reviewed: 8 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.