Egg development

There are different stages of an egg’s development as it matures in the follicle.

It goes from GV –> M1 –> M2.

The earliest stage is the germinal vesicle stage (GV), where you can see the nucleus of the egg. After the GV stage, the nucleus is no longer visible and the oocyte is in the M1 stage. Both a GV and M1 egg are immature.

After the M1 stage, the egg enters the M2 stage and a polar body is seen. The presence of a single polar body is how you know an egg is mature, and is ready to be inseminated.

On the left, the arrow is pointing to a germinal vesicle inside the egg. On the right, the arrow is pointing to a polar body, which is characteristic of an M2, or mature egg. Modified from Ghevaria et al. (2022), CC by 4.0

Read more here.

Synonyms:
egg maturity, mature egg, mature oocyte, oocyte maturity, GV, M1, M2, germinal vesicle, immature egg, immature oocyte, MI, MII