The quality of the eggs obtained with egg collection is as important as the number of the eggs. Mature eggs of good quality (MII) are processed.
For a successful fertilization, division and development, the quality of the egg is very important.

The quality of the egg and whether they are mature or not are determined as follows:

• Immature oocyte (prophase): No polar substance present, germinal vesicule is dark, compact cumulus is present.
• MI oocyte (metaphase I): Polar body, germinal vesicule are not present, cumulus is wide and the oocyte is slightly colored.
• MII oocyte (metaphase II): Polar body present, ooplasm regular, cumulus has a wide appereance.
• Postmature oocyte: Cumulus in bulk or not present, polar body present, ooplasm has a dark appereance.
• Degenerated oocyte (atretic): No cumulus present, polar body and the nucleus has a degenerated appereance, vacuole present.

MI oocyte

MII oocyte